Heiko G. Rödel

Abstract: Weather conditions can have a significant influence on short-term fluctuations of animal populations. In our study, which is based on time series of hunting bag records of up to 28 years from 26 counties of The Netherlands and Germany, we investigated the impact of different weather variables on annual counts of European rabbits (Oryctolagus cuniculus) and European hares (Lepus europaeus). Overall, the long-term dynamics of both species could be described by higher-order polynomials. On a smaller time scale, numbers of European hares shot were lower in years with higher amounts of precipitation during late summer/autumn, and numbers of European rabbits shot were lower in years with high precipitation in spring of the respective year. We suggest that rainy weather conditions might have lowered the survival of young rabbits in spring and might have generally facilitated the outbreak or spread of diseases in rabbits as well as in hares, specifically in autumn. In addition, the results showed a time-delayed, interactive effect between precipitation in spring and winter weather on European rabbit dynamics: rabbit numbers were limited by low temperatures of the prior winter season, but only when precipitation was high during spring of the previous year. The latter result might be explained by the lowering effects of rainy spring weather on the body condition of the animals, leading to a higher sensitivity to harsh winter conditions. In conclusion, our study provides evidence for the impact of weather conditions on the population dynamics of both study species and particularly highlights complex interactions between the prevailing weather conditions during different seasons in the European rabbit.

Abstract: Although monogamy is interpreted as risk-adverse strategy by reducing intra-sexual conflicts, most pair-living males increase their reproductive success by engaging in extra-pair copulations. However, little is known about costs involved in such extra-pair attempts from the male�s perspective. We investigated promiscuous tendencies of paired male and female Macroscelides proboscideus (common name: round-eared elephant-shrew or round-eared sengi), a pair-living small mammal occurring in southern Africa. In particular, we measured potential costs of extra-pair attempts for the males. For this, we conducted laboratory experiments, involving interactions between neighbouring pairs. Data collection included direct behavioural observations and establishing the morphological and physiological characteristics of males. Both sexes intruded into the neighbouring area, and initiated sexual behaviour with neighbours of the opposite sex. Males which displayed a higher marking frequency in the neighbouring area received more sexually motivated behaviour initiate by neighbouring females. Resident males attacked intruding males. Aggression experienced by and marking behaviour of intruding males was positively correlated with body mass losses. Furthermore, glucocorticoid levels, determined from analyses of faeces and urine samples, correlated positively with body mass losses and marking behaviour of intruding males, indicating costs of intruding. We conclude that male as well as female round-eared sengis have promiscuous tendencies. Although interactions with neighbouring females may offer potential benefits for males in terms of enhanced reproductive success, males also seem to pay substantial costs, as indicated by body mass losses and elevated stress hormone levels.

Abstract: Individual consistencies over time in the behavioral responses to challenging situations are usually considered as an indication for the existence of animal personality types. Although such consistencies have been found in a variety of species, information on long-term stabilities is scanty, in particular across different life history stages such as reproductive and non-reproductive periods, which have the potential to impact considerably on the behavioral responses of animals. In our study of adult female laboratory mice, we explored the stability of behavioral responses across a 43-day period by successively testing the animals on an elevated plus maze. We tested two groups, one group that had offspring during the first two tests but not during the last test, and the other group that only had offspring during the last test situation. We found clear evidence for individual consistencies over time by means of positive significant correlations across the different test situations: Animals that spent more time in the closed arms of the plus maze and those that entered the open arms more often during the first test also tended to do so during the second test - when still in the same reproductive state, and also during the third test - when in a different reproductive state. In addition, females of the two groups did not differ overall in their responses, although we found a significant increase in the frequency and duration of presumed anxiety-related behaviors during the course of the experiment, contradicting the notion that habituation effects should attenuate the challenge of the test situation. In conclusion, our study strongly suggests the existence of stable personality types in female laboratory mice, even across different reproductive stages.

Abstract: Estimating population age structures by faecal pellets sizes is a commonly used field method in some mammal species. We examined the validity of this method in European rabbits based on 1113 pellets from 226 animals with known age, by measuring the intra-individual variation in pellet size and studying the explained variance of calibration curves describing the relation between pellet size and individual age. In addition, we applied a simulation model in order to estimate the accuracy of this method. Pellet size showed a high intra-individual variation and was only moderately correlated with the animals' age. Modelling revealed that the population age structure assessed by this method deviated considerably from the given structure, indicating a systematic estimation error. We conclude that this method can lead to strongly biased results, restricting its validity. We provide estimation errors, which might be considered if estimates of age structure in wild rabbits populations based on faecal diameters are conducted.

Abstract: The European rabbit Oryctolagus cuniculus is an important model system in the study of mammalian maternal behavior. This is at least partly due to the rabbit�s unusually limited pattern of maternal care, characterized by the mother briefly visiting the young to nurse just once approximately every 24 hours. In studies of domestic breeds under laboratory conditions it has been found that females show a rather predictable interval between these once-daily visits. However, as there are reports of considerable inter-individual variation, the aim of our study was to identify factors with the potential to modify the rabbit�s diurnal pattern of nursing, such as characteristics of the mother, litter size and also potential changes in the nursing interval length during the early postnatal period. We studied the time course of nursing visits in wild-type rabbits in the natural setting of a large field enclosure in order to obtain results unbiased by laboratory artifacts. Using an automatic portable gas analyzer, we monitored the timing of nursing events by recording the change in oxygen concentration within natural breeding burrows occurring when mothers entered to nurse and calculated the interval length between successive nursing events. During the first nine postpartum days, when our study was conducted, rabbit mothers on average showed a nursing interval of about 24 hours. Return intervals remained rather constant in mothers of larger litters but decreased in mothers with smaller litters, resulting in them visiting their young to nurse a little earlier each night. Mothers� age, day length and season did not affect nursing intervals. In conclusion, our study confirms that under natural conditions rabbits nurse their young only once approximately every 24 hours, but that this pattern is not completely fixed and can be modulated by litter size, possibly via the strength of sucking stimulation received by the mother during nursing.

Abstract: High mortality in rabbit rearing is not only an economical problem but also an animal welfare issue. Without doubt, the main reasons for the high mortality rates are some common rearing practices. In this review, we point out different and commonly used management practices, which neither represent adequate housing conditions according to the animals� behavioural requirements nor correspond to their nutritional needs, and discuss possibilities to reduce the risk of disease. (1) Usually the doe is forced to build the nursery nest in the cage or in a box with a permanently open entrance, often not protected from the light. This can lead to perinatal mortality due to disturbed behaviour of the mother such as failure to build a proper nest, depositing the kits outside the nest, or infanticide. (2) Continuous housing of the doe with the kits does not conform to this species� pattern of unusually limited maternal care. Stimulated by olfactory and acoustic signals emanating from the nest, the doe disturbs the inactivity of the kits by her frequent entries to the nest or attempts to close the entrance. Cooling of the kits caused by maladaptive maternal behaviour under such unnatural conditions is one of the most important causes of mortality and morbidity during the nursing period. (3) When the doe is left to nurse the kits longer than four weeks, which does not conform to the reproductive biology of the rabbit, kit morbidity is caused by the following factors: (a) Prolonged mother-offspring contact increases the risk of the kits becoming infected with pathogens such as coccidiosis, EPEC and pasteurellosis persisting in the doe. (b) Pre-disposition of the kits to bacterial enteropathies is encouraged by the delayed development of the enzymatic system, the delayed establishment of a stable gut flora (due to the use of wood shavings or straw as nest material), as well as by consumption of the doe�s feed. (c) The increased energy demands of lactation as well as mastitis due to excessive and prolonged suckling by the kits decrease the fertility and the lifespan of the doe. (4) Feed with a high content of non-fibre carbohydrates (compared to green forage) promotes bacterial enteropathies when given before the development of the kits� digestive functions is completed. In addition, the risk of the outbreak of such diseases is enhanced by intestinal coccidiosis and unstable gut flora. (5) In contrast to housing rabbits on perforated floors, the use of cages with deep litter increases the risk of enteropathies.

Abstract: Many aspects of an animal's early development might potentially contribute to long-term individual differences in physiology and behavior. Here we asked whether differences among littermates of the domestic rabbit in the position in the litter huddle that they occupy during the early nest period might contribute to the development of distinct behavioral and physiological phenotypes. In each of 12 litters we determined the pup occupying the most peripheral, the most central, and an intermediate position in the huddle during the first postnatal week. We then tested the responses of these same individuals as nestlings, juveniles and young adults when confronted by a range of age-appropriate environmental challenges. Two behavioral tests appeared particularly discriminatory in identifying differences associated with early position in the huddle; latency of pre-weaning pups to jump down from a shelf, and the response of young adults to the fearful screams of a conspecific. In both cases animals that had occupied the periphery of the huddle showed behavioral responses indicative of a more proactive behavioral style than their �intermediate� or �central� littermates. We conclude that while consistent long-term differences in behavioral style associated with early position in the litter huddle exist in rabbits, future work is needed to confirm the causal nature of this association, to identify underlying mechanisms, and to refine methods of behavioral and physiological testing across the life span.

Abstract: A number of short-lived, iteroparous animal 1 species have small broods in the early breeding season and larger broods in later breeding season. Brood size affects not only offspring size, but as recent results suggest, may also affect offspring�s temperament, hormonal status and aggression as adults. Most populations of short-lived, iteroparous mammals fluctuate predictably over the season, with low densities in winter, increasing densities in summer and a population peak in late summer followed by a population breakdown. If animals live only through parts of the season, possibly such differences in density and hence also in social environments among seasons require different personality 9 types to increase individual fitness. We present data on behavior of European rabbits from a field enclosure study. These data clearly show that aggressiveness is higher in young from smaller litters than in young from larger litters, and smaller litters are usually born during the early breeding season. Moreover, our data suggest that behavioral types of the young rabbits are stable over time, at least during their subadult life. We suggest, that changes in mean litter size over the course of the breeding season may not only be a product of mothers� age or food availability, but may also have an adaptive function by preparing offspring characteristics for adulthood in a social environment undergoing predictable density changes within the season.

Abstract: Many aspects of an animal�s early development contribute to the emergence of individual differences in physiology. Here we asked whether litter size, birth mass, suckling success and postnatal growth were predictors of individual differences in testosterone (T) and corticosterone (CORT) levels in neonatal domestic rabbits. Serum concentrations of both hormones, which we measured on postnatal day 8, were significantly and positively correlated with pup growth and milk intake. Litter size and birth mass were not significantly correlated with levels of T and CORT, although both parameters were indirectly associated with the levels of these hormones via their effects on milk intake and pup growth. Our results highlight the importance of naturally occurring features of the postnatal environment in shaping individual differences in T and CORT levels during early life.

Abstract: Early life parameters such as litter size and growth are frequently associated with an animal�s behavioral performance or motor skills as well as with its stress responsiveness. All these traits can be involved in the ontogeny of behavioral phenotypes, and therefore we wanted to know whether individual litter size and early growth also show long-term correlations with the animals� behavioral responses to challenges around maturity. We collected data on the early postnatal development of individually marked European rabbits living in a field enclosure and conducted two standardized behavioral tests shortly before the animals matured. In small enclosures, we experimentally tested their behavioral responses (1) in this novel environment and (2) to the confrontation with predator odor. Animals, which were more exploratory during the novel environment test showed lower behavioral signs of anxiety during the predator test. Both responses were correlated with individual pup body mass, with subjects with higher body mass being more exploratory in the first test and showing lower levels of anxiety in the second. The animals� current body mass or age when being tested, were not correlated with any of their responses. First, the correlated responses of the animals during the different contexts of the applied tests strongly suggest the existence of behavioral types in European rabbits. Second, and most importantly, our study provides evidence that an animal�s early development can exert long-term effects on its personality type, although it is not clear whether body mass per se or some correlated physiological features drive the observed relationships.

Abstract: Although most mammals grow up in the company of same or different age sibs (or half sibs), surprisingly little attention has been given to how relations among them might influence the development of individual differences in morphology, physiology, and behavior. Here we review evidence from our work on domestic and wild European rabbits, and more recently on laboratory rats, mice, and domestic cats, supporting the proposition that in mammals early sibling relations contribute to the development of individual differences in these three domains and thereby to long-term behavioral differences of the kind we might consider part of an animal�s behavioral style or personality. First we report a consistent and marked negative relation between litter size and individuals� body mass at birth and weaning, as well as marked within-litter differences in prenatal body mass and placental efficiency. We then report individual differences in preweaning behaviors associated with these morphological variables such as position occupied in the litter huddle and development of motor ability, as well as physiological differences in thermoregulation, immune parameters, and endocrine indicators of stress. Finally, we report first evidence from wild rabbits that early relations among littermates may have longterm consequences for individual differences in behavioral style.We conclude that in mammals, individual differences in early growth, physiology and behavior potentially important for the development of animal personality, are shaped to an appreciable extent by early sibling relations and that this little-researched field deserves closer attention.

Abstract: Features of an individual�s early development are frequently reported to alter the postnatal ontogeny in litter-bearing mammals with respect to various physiological parameters. We hypothesized that such effects might also apply to the ontogeny of personality types. On the one hand, litter size effects by means of more contacts with littermates, might lead to the development of more offensive types. On the other hand, smaller and less developed young from larger litters might be less offensive due to their lower physical capabilities to deal with challenging situations. We studied these contrasting hypotheses in young rats, which we tested in a battery of emotionality tests. There were clear indications for the existence of distinct behavioral types by means of consistencies in behavioral responses within and across contexts. Based on these responses, we calculated three new variables by PCA, which we interpreted to mainly reflect boldness, exploration, and anxiety. Overall, our results strongly suggest that the early development alters the ontogeny of personality types, with heavier individuals being bolder and more explorative. Furthermore, body mass and litter size influenced the changes in the behavioral responses in successive tests, further supporting the importance of the litter size-dependent body mass for the ontogeny of personalities. Anxiety also depended on litter size, however, in a nonlinear way. Animals born to litters of small or large sizes had higher scores, whereas individuals from medium-sized litters were less anxious. This optimum curve indicates that opposing effects of litter size are involved in shaping personalities in young rats.

Abstract: Genes of the major histocompatibility complex (MHC) play a fundamental role in the vertebrate immune response and are amongst the most polymorphic genes in vertebrate genomes. It is generally agreed that the highly polymorphic nature of the MHC is maintained through host-parasite co-evolution. Two nonexclusive mechanisms of selection are supposed to act on MHC genes: superiority of MHC heterozygous individuals (overdominance) and an advantage for rare MHC alleles. However, the precise mechanisms and their relative importance are still unknown. Here, we examined MHC dependent parasite load in European rabbits (Oryctolagus cuniculus) from a distinct population with low MHC diversity (three alleles, six genotypes). Using a multivariate approach, we tested for associations of individual MHC class II DRB constitution and the rabbits' intestinal burden with nematodes and coccidia. Rabbits having a particular allele showed lower infestations with hepatic coccidia (E. stiedai). However, a comparison of all six genotypes in the population revealed that carriers of this allele only benefit when they are heterozygous, and furthermore, MHC heterozygosity in general did not affect individual parasite load. In conclusion, this study suggests an immunogenetic basis of European rabbit resistance to hepatic coccidiosis, which can strongly limit survival to maturity in this species. Our study gives a complex picture of MHC-parasite correlations, unveiling the limits of the classical hypotheses of how MHC polymorphism is maintained in natural systems.

Abstract: The size of an individual's home range is an important feature, influencing reproduction and survival, but it can vary considerably among both populations and individuals. The factors accounting for such variation are still poorly understood, and comprehensive long-term field studies considering various environmental factors that influence home range size are rare. We investigated the effects of seasonality, availability of food, cover, number of direct neighbours and the relative individual body mass on home range sizes in 125 adult female striped mice, Rhabdomys pumilio, in South Africa from 2004 to 2008. We used radiotelemetry to estimate home range sizes, trapping to determine the number of direct neighbours, and plant surveys in every home range to determine availability of food and cover. Home ranges were smaller when food quantity was high, many territorial neighbours were present, females had a relatively small body mass and during the nonbreeding season. We conclude that the availability of food resources and intraspecific competition are the main factors influencing home range size in female striped mice. Females enlarged their home ranges when territorial neighbours were few, and there was a significant positive correlation between home range size and quantity of food plants. This indicates that home range size might not reflect the minimal trade-off between access to resources that allow for a female's survival and lowest cost for defending and foraging in that area. Instead, we propose a hypothesis for future research that female striped mice occupy areas several times larger than needed to improve their fitness by providing resources for future offspring. (C) 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Abstract: Early postnatal growth in mammals can be considerably influenced by litter size and often differs among littermates in relation to birth mass. In a study of Long Evans laboratory rats we asked whether within- and between-litter differences in body mass and growth are related to behavioral development during early, postnatal life. For this, we analyzed the amount of general motor activity and the display of directed, seemingly goal-oriented interactions within the litter huddle in previsual pups. During the study period from postnatal days 2 to 11, we found significant changes in pup behavior, showing a nonlinear quadratic shape. General motor activity and, more specifically, the display of behaviors apparently directed to reaching central positions in the litter huddle increased during the first postnatal days and then decreased again. However, pups from small litters that grow more rapidly than pups from large litters, showed a faster increase in both behaviors, whereas the young from large litters reached a higher maximum. We also found striking within-litter differences in the amount of directed behavior performed by light and heavy pups, with higher levels in the former group, most probably because light pups that have a less favorable body mass-to-volume ratio and more often occupy peripheral positions in the litter huddle, make a greater effort to reach thermally favorable central positions. In conclusion, our study shows there to be consistent between-litter as well as within-litter differences in behavioral patterns during early life. These differences might have important implications for an individual's long-term behavioral and physiological performance. (C) 2009 Wiley Periodicals, Inc. Dev Psychobiol 52: 35-43, 2010.

Abstract: An animal's environment during early life can strongly affect its physiological development. For example, litter size, i.e. the number of litter siblings, has been previously shown to strongly affect early growth in many small mammal species including laboratory rats. In the present study we tested whether natural, unmanipulated litter size is also associated with differences in stress hormone levels in young Long-Evans laboratory rats. We found a negative correlation between serum corticosterone (CORT) concentrations and litter size during two different stages of juvenile life. On postnatal day 17, shortly before weaning, this relationship was apparent with respect to basal CORT values. On day 33, however, two weeks after weaning, we found this relationship only when animals were challenged by a 10-min test on an elevated plus maze, but not in control animals (basal values). Although the physiological basis of these differences is not clear, we discuss two main, not mutually exclusive possibilities: (a) delayed maturation of the HPA axis in typically lower body mass pups of large litters, and (b) that such pups, encountering greater competition for maternal resources, adjust to this presumably more stressful developmental environment by down-regulating responsiveness of the HPA axis. In conclusion, our study provides evidence that a naturally varying feature of the developmental environment of many altricial mammals number of littermates may contribute to individual differences in stress-related physiology. Furthermore, it suggests the need to consider litter-size effects when investigating differences in animals' stress responses. (C) 2010 Elsevier Inc. All rights reserved.

Abstract: A functional immune system is important for the survival of mammalian young, particularly at weaning when they lose the Immunological support provided by the mother's colostrum and milk In altricial mammals, litter size and maternal characteristics are important components of an animal's early environment, which affect postnatal growth and development In a study of unculled litters of Long-Evans laboratory rats (Rattus norvegicus). we asked whether such parameters are also associated with the immune status of the young shortly before weaning On postnatal day 17, we assessed numbers of several leukocyte and lymphocyte subsets, the activity of the complement system, and immunoglobulin G (IgG) concentrations in the serum Averaging the values of all pups pet litter, we found negative correlations between litter size and lymphocyte counts, complement system activity and IgG concentration Maternal effects were seen in the positive correlation between maternal postpartum body mass and granulocyte and monocyte counts In addition, lymphocyte and monocyte counts as well as complement activity wet e lower for the young of multiparous than of primiparous mothers. This suggests a trend towards a better developed immune system in such offspring, which may be relevant for their immediate and long-term survival The effects described here have potential implications for the design and interpretation of biomedical studies of immune parameters in laboratory rats (C) 2010 Elsevier Inc All rights reserved

Abstract: We conducted a study on nest mortality of an individually marked population of European rabbits (Oryctolagus cuniculus L., 1758) living in a field enclosure. Over 4 years, we determined maternities and quantified pup mortality during the nest period of 703 pups born in subterranean breeding burrows. Overall, pup mortality occurred in 42.7% of the litters, whereas 32.4% of all born pups were affected. Mortality was highest during the first few postnatal days. In about 50% of the cases, we managed to quantify different causes of mortality such as malnutrition, flooding, cooling of the pups. infanticide, or predation. The pups' body mass on postnatal day 1, the thermal environment and the number of litter mates were the most important predictors of nest mortality. Litter mortality risk decreased with increasing soil temperature around the subterranean nests. A comparatively higher average pup body mass lowered the nest mortality risk of a litter, whereas this effect was snore pronounced when soil temperatures were low. Furthermore, mortality was lowest in medium-sized litters, most probably due to the balance between the thermal benefits of huddling with litter siblings and the costs of having them due to the lower shire of milk obtained by the individual pups in larger litters. In addition, nest mortality depended on characteristics of the mother; mortality was increased in litters of low-ranking females and of mothers with lower body mass. In conclusion, our study highlights multiple causes and the effects of different environmental and social factors on nest mortality of this small mammal. (C) 2008 Deutsche Gesellschaft fur Saugetierkunde. Published by Elsevier GmbH. All rights reserved.

Abstract: During the early juvenile period, animals are especially prone to heat loss due to their high surface area to volume ratio. Consequently, adverse environmental conditions such as low ambient temperature and wetness affect the energy balance in juveniles more strongly than in adults. Our main study goal was to experimentally measure the influence of low ambient temperatures and wet fur on resting metabolic rates (RMR) and on thermal conductance in young, pre-weaned (wild-type) European rabbits (Oryctolagus cuniculus L.), i.e. shortly after young rabbits in the wild usually leave the breeding burrow. We predicted that a higher body mass and therefore a more favourable surface area to volume ratio might decrease the responses of the juveniles to adverse weather conditions. Furthermore, huddling with siblings might buffer the negative influences of low temperature and wet fur. Using studies in field enclosures, we first evaluated the occurrence of huddling in juvenile European rabbits, and recorded the variation in ambient temperature experienced by the young. In laboratory experiments, we then measured RMR in single and pair-housed (huddling) juveniles with dry and wet fur under different ambient temperatures reflecting the conditions experienced by same-aged rabbits in the wild. We found interacting effects of temperature and wetness on RMR and on thermal conductance, which increased more strongly with decreasing temperature when the animals were wet. In addition, RMR decreased significantly with increasing body mass, but only under wet conditions when the temperature was low. Pre-weaned juveniles in the field enclosures almost exclusively huddled in pairs but not in larger groups, probably because of the high juvenile mortality, which was strongly limiting the number of litter mates. In laboratory experiments, we did not find significantly lower RMR or thermal conductance in huddling pairs than in single juveniles. The occurrence of huddling, in the field and in the laboratory, was also not related to ambient temperature conditions. Our study highlights the importance of a high juvenile body mass which helps to reduce maintenance costs under adverse environmental conditions. Such effects might have important implications for the individual's pre-weaning growth and development and may exert long-term effects on fitness-related traits.

Abstract: Mate guarding is predicted to be one of the driving forces for the evolution of monogamy, but supporting evidence in free-living mammals is rare. The goals of our study were three-pronged. First, we tested if mate guarding, measured as intrapair distance, occurs as a behavioral tactic in round-eared sengis (Macroscelides proboscideus), a socially monogamous species lacking paternal care and in which females breed asynchronously, producing 2-3 litters during an 8-month long breeding season. Second, we determined if mate guarding involves costs which we identified as changes in male body mass. Third, we investigated whether variation in individual investment in mate guarding depended on the males' body mass and the number of neighboring males. Field data were collected in a semidesert in South Africa using radio-tracking, trapping, and direct observations during three successive breeding seasons. Mate guarding strongly depended on the females' reproductive state, and all males started to guard their mates prior to and during estrus, as exemplified by reduced intrapair distance. Mate guarding incurred costs: overall, males lost about 5% of body mass. Male body mass loss and initial body mass were negatively related to the intensity of precopulatory mate guarding. Furthermore, during estrus intrapair distance was inversely correlated with the number of neighboring males. The results show that mate guarding is the predominant male tactic in round-eared sengis. However, since mate guarding imposed costs, males may balance benefits and costs associated with guarding by varying their effort in relation to their physical capabilities and the competitive environment.

Abstract: Lactating rabbit females (Oryctolagus cuniculus) emit abdominal, ventral odour cues that are involved in guiding the pups to the nipples. We tested the impact of the females' social rank and age on the emission of this odour signal; both factors are highly collinear in wild rabbits and we did not aim to disentangle them in our study. We predicted that the abdominal odours of young, low-ranking females, which are usually more stressed and have a comparatively lower body condition, should be less attractive to pups than those of older, high-ranking females. For the experiment, we caught females from a population of wild-type European rabbits living in a large field enclosure. Pairs of adult females were placed in boxes with wire-mesh floor fixed over an arena with three rabbit pups aged 4-7 days old. First, we evaluated the effectiveness of our two-choice design by testing lactating females (LF) against non-lactating (NLF) controls (n = 17 pairs). In accordance with recent studies, the pups showed a clear preference for lactating females by means of a higher exploration time and more local searching under the ventral region of these females. In a second experiment, the pups chose between lactating 1-year-old, low-ranking females (Y/LRF) and older, high-ranking females (O/HRF) (n = 10 pairs). These latter assays suggested a comparatively lower attractiveness of Y/LRF females to pups searching for milk. Although the pups showed no significant preference in exploration behaviour, they preferably directed local searching events to the abdominal region of O/HRF females. In conclusion, our study suggests that mother-offspring chemosensory communication is modified by the mother's age and social rank, i.e., by a complex of factors that are strongly linked in rabbit females in the wild.

Abstract: An animal's level of vigilance depends on various environmental factors such as predator presence or the proximity of conspecific competitors. In addition, several individual traits may influence vigilance. We investigated the effects of body condition, social rank and the state of pregnancy on individual vigilance (scanning) rates in individually marked European rabbits (Oryctolagus cuniculus) of a field enclosure population. We found lower rates in young rabbits than in adult females, but male and female juveniles did not differ. Vigilance of juveniles was positively correlated with their age-dependent body mass (used as a measure of body condition), i.e. young rabbits with lower body condition scanned less. We suggest that juveniles with low body condition were trading off vigilance against feeding to maximise their growth. In contrast, there was no significant correlation between body mass and vigilance in adult females. Adult females increased scanning rates during late pregnancy, which might constitute a behavioural compensation because of their lower capacity to escape predator attacks. In addition, adult females with low social ranks scanned more than high ranking individuals, likely because of their higher risk of attacks by conspecifics. In summary, our results highlight various individual characteristics that influence vigilance behaviour in European rabbits.

Abstract: The outcome of an intra-specific aggressive encounter between two competitors is frequently influenced by differences in individual characteristics. Apart from differences in adult body condition, aspects of the early juvenile development, which are commonly found to influence traits during later life, may be of particular importance. In an observational study on individually marked European rabbit males (Oryctolagus cuniculus L.) from a field enclosure, we investigated short-term and long-term consequences of different features of the early development on measures of competitive performance during later life. Males from smaller litters, which consequently had a higher nestling body mass, showed more escalated offensive behavior (chasing) against other juveniles during juvenile life. Furthermore, such males were more offensive and successful fighters in intra-sexual conflicts during their first breeding season. Interestingly, when comparing the effects of different measures of body mass during different life stages, the nestling mass was the best predictor for male competitive performance after maturity. The body mass measured during the late juvenile stage in autumn was also significantly, but more weakly correlated with the males' offensive behavior after maturity, whereas the adult body mass did not show significant effects. In conclusion our study points out, that parameters of the early development are involved in shaping the competitive performance during later life via other mechanisms than just by promoting a high adult body mass. (C) 2009 Elsevier Inc. All rights reserved.

Abstract: Environmental conditions during an animal's early life can have profound long-term consequences and affect its fitness. In particular, maternal and sibling effects, which can strongly influence the early growth of altricial mammals may be important. Few studies have investigated the influence of such early-life parameters in small mammals, because in these species the early post-natal stage is difficult to monitor under natural conditions. We quantified the effects of litter size (i.e. number of litter siblings), maternal social rank and age and reproductive history of the mother (i.e. whether or not the mother had given birth to a previous litter during this season), and the individual date of birth and social rank on two fitness components of female European rabbits (Oryctolagus cuniculus L.) from a field enclosure population. Analyses were based on data on survival to maturity of 1836 female pups from 10 annual cohorts, and on lifetime reproductive success (LRS; here: the summed up number of offspring surviving to maturity) of 81 adult females from eight annual cohorts. Both fitness components were correlated with the size of the females' original litter and with the age of their mother. Litter size was related to survival to maturity and to LRS in a nonlinear (quadratic) way being highest in females from medium-sized litters. Maternal age also exerted quadratic effects on LRS, which peaked in females born to 2- to 3-year-old mothers. In contrast, survival to maturity increased with increasing age of the mother. Survival to maturity and LRS were decreased in females born later in the breeding season, likely because of the longer time for growth that early born young enjoy before the winter season. In addition, LRS was lower in females which occupied a higher social rank at the onset of their first breeding season. Our results emphasize that factors during early development, in particular parameters of the early social environment, do not only affect juvenile survival but have the potential to exert long-term fitness consequences throughout life.

Abstract: Newborn rabbits rely on odour cues to localize and seize maternal nipples. In particular, they orally respond to the mammary pheromone (MP) emitted in rabbit milk. The activity of the MP was so far mainly investigated in newborns, and a drop in its releasing effect was shown in 23-day old pups. Here, we evaluated the activity of the MP in a large sample (n=1588) of domestic rabbit pups tested between birth and weaning. We also assessed whether wild-type pups respond to the MP, and whether the developmental course of their responsiveness matches the one of domestic pups. During the first postnatal week, the MP revealed to be a strong releasing stimulus in all pups, regardless of their genetic and environmental background. However, the saliency of the MP decreased with approaching weaning, and this decrease was clearly steeper in wild-type than in domestic pups. These results are discussed with regard to the concept of ontogenetic adaptation and the effects of artificial selection.

Abstract: Birth mass can vary considerably among mammalian littermates. Heavier pups often show higher growth rates than their lighter siblings, which might positively affect fitness-relevant parameters during later life. Such a correlation between birth mass and pre-weaning growth within litters was confirmed by our study of wildtype and domestic European rabbits (Oryctolagus cuniculus) living in a semi-natural environment and under laboratory housing conditions. respectively. Our study indicates that at least two main mechanisms account for this relationship in our study species: heavier pups had a higher milk intake and also showed a more efficient conversion of milk into body mass. Furthermore, our study suggests that the better milk conversion by heavy pups was driven by three synergistic mechanisms: heavier pups had comparatively more huddling partners in the nest, they did not need to perform large amounts of proactive behavior in order to reach and remain in a central position within the litter huddle, and they could maintain a comparatively higher body temperature most probably due to their more favorable surface area to volume ratio. In conclusion, our study of European rabbits provides strong evidence that both under natural conditions and in the laboratory, within-litter differences in birth mass are maintained and may even increase during pups' early postnatal development. (C) 2008 Elsevier Inc. All rights reserved.

Abstract: Blind and deaf at birth, rabbit newborns need, as all mammal newborns, to rapidly interact with the mother to find the nipples and suck. This usually occurs only once per day, during an interaction drastically limited in time, both in domestic and natural conditions. After days 10-15, the mother-young interactions change progressively, leading to weaning between 4 and 6 weeks. In this context of rapid development of the young, lactating rabbit females and pups have developed some sensory, physiological and behavioural adaptations allowing them to communicate, and allowing the young to ingest milk then solid food efficiently. Here, we present some of these adaptations, taking examples from experimental studies run by several groups during the last decades. This paper is a summary of a chapter and communication recently presented during the last World Rabbit Congress (Coureaud et al 2008b).

Abstract: Growth during an animal's early ontogeny can have important consequences for its health, reproduction and survival during later life. We studied pre-weaning growth rates of two species of small altricial mammals, and assessed the impact and compared the importance of two main aspects of the animals' early environment: maternal characteristics and the number of litter siblings (i.e. litter size). Study animals were wild-type European rabbits living in a field enclosure and laboratory rats kept under standardized housing conditions. Growth of rabbit pups was best explained (to 47%) by the combined effects of litter size, maternal age and whether females had given birth to another litter shortly before. Similarly, growth in rat pups was best explained (to 75%) by the combined effects of litter size, maternal body mass and whether mothers had previously given birth. In both species, litter size correlated negatively with pup growth. In rabbits, growth was greatest in litters of middle-aged females. In rats, pup growth correlated positively with maternal mass. Pups of both species showed higher growth rates when the mother had not given birth to a previous litter. Despite major differences in maternal behaviour and study conditions between the two species, the findings point to a similar ranking in the importance of the different parameters tested: Litter size, i.e. sibling number, was the most important factor, followed by maternal mass or age, and then by mothers' history of previous reproductive activity. We therefore think it likely that these findings will be valid for other mammalian species giving birth to large litters of altricial young. (c) 2007 Elsevier Inc. All rights reserved.

Abstract: In altricial mammals and birds, the presence of a large number of litter or brood mates often affects the development of individual offspring by reducing the share of resources provided by the parents. However, sibling presence can also be favourable, conferring thermoregulatory benefits when ambient temperatures are low. Consequently, shifts in the relation between costs and benefits of sibling presence can be expected as a function of the thermal environment. In a study of a European rabbit population (Oryctolagus cuniculus) living in a field enclosure, we investigated the effects of litter size and soil temperature on pup growth over 7 years. Temperatures inside the subterranean nests were positively correlated with soil temperature and with litter size. Soil temperature varied strongly across the breeding season, ranging from 3 to 21 degrees C. Under warmer soil temperature conditions (10-15 degrees C and > 15 degrees C), pup growth decreased with increasing litter size, where litters of two pups (smallest litter size considered) showed the highest growth rates. In contrast, under colder soil temperature conditions (< 10 degrees C), the highest growth rates were found in litters of three pups. We also asked if such temperature-dependent differences in the optimal pup growth rates might be explained by differences in maternal characteristics, which might affect lactational performance. We assessed maternal performance using females' postpartum body mass and social rank. However, we did not find consistent differences in maternal characteristics between females giving birth to different-sized litters during different soil temperature conditions, which would have provided an alternative explanation for the observed differences in litter size-dependent pup growth. We conclude that under colder soil temperature conditions, the thermal benefits of a greater number of littermates outweigh the negative consequences of competition for milk, leading to an environment-dependent shift in the optimal litter size for individual growth in this species.

Abstract: Infanticide is an important source of mortality of dependent offspring in several mammal species, whereas female conspecifics are often the perpetrators. This has led to maternal counter-strategies, such as the defence of the nests. However, cases of infanticide are hard to detect in the field, and studies on maternal offspring defence behaviour under natural breeding conditions are scarce. We conducted such a study on the European rabbit (Oryctolagus cuniculus), which is usually considered to show low maternal care. The study was carried out over 5 yr on a field enclosure population. We (1) studied infanticide rates and the impact of potential determinants: the group density and age structure of the females' rank hierarchy within the groups; we used the latter as an estimator of social group stability. We (2) studied if mothers defend their breeding burrow against approaching, potentially infanticidal females. Overall, we recorded infanticide in 5% of all litters; infanticide was the cause in 12% of cases of litter mortality. The proportion of infanticide was 7% higher in groups where same-age females occupied successive rank positions than in groups where the females' rank hierarchy had a more heterogeneous and linear age structure. We hypothesize that social instability in the former groups was the reason for the increased infanticide risk. Infanticide rates were not correlated with group density and did not differ among mothers with different social ranks. Infanticide occurred exclusively during the first 10 d after parturition. During this time, mothers stayed closer to their breeding burrows than shortly before parturition or during later lactation. Moreover, mothers were more aggressive against other females in proximity to their breeding burrow than in more distant areas. We suggest that the pattern of spacing behaviour and intrasexual aggression of rabbit mothers are an adaptive response to the occurrence of female infanticidal behaviour.

Abstract: In group-living mammals, the major functions of vigilance are to detect the presence of predators and to monitor the movements of conspecific competitors, i.e. of potential opponents in agonistic encounters. The minimum distance to such a conspecific competitor that an animal considers safe is usually lower than to a predator, whereas the frequency of encounters with conspecifics is higher. Therefore, the acquisition of information about a predator or about a conspecific could lead to the existence of at least two different modes of vigilance behaviour. The aim of the present study was to describe and compare different forms of vigilance behaviour that European rabbits, Oryctolagus cuniculus, display in anti-predator and social contexts. We conducted an observational study on individually marked animals from a field enclosure population. We recorded social interactions of the animals, the presence of aerial predators (common buzzard Buteo buteo), and the vigilance behaviour of the rabbits. We distinguished between two forms of vigilance of different intensity: subtle and overt. The frequencies of both forms of vigilance displayed by the rabbits differed significantly in occurrence, duration, and distribution over time. Females and males showed higher frequencies of overt but not subtle vigilance when buzzards were present. In contrast, the presence of conspecifics in close proximity affected the display of subtle but not overt vigilance: males increased the frequency of subtle vigilance when other males were close. Females increased subtle vigilance in proximity of males and females; however, this effect was only apparent in females with a more unstable social situation. In conclusion, European rabbits differentially increased two different forms of vigilance behaviour in social and anti-predator contexts.

Abstract: The authors investigated in an observational study the consequences of the presence of litter sisters on the social interactions and on reproductive performance of young female European rabbits (Oryctolagus cuniculus) from a population living under seminatural conditions. In early winter, when all young females were settled in a social group, they were characterized by the presence or absence of litter sisters in their groups. Females with litter sisters in their groups displayed significantly more positive social interaction with females of their social group compared to females without sisters, whereas this difference was mainly due to the high frequency of positive social interactions among the respective sisters. Such differences between the females of both categories were already apparent during the animals' juvenile phase, before the females integrated into a particular group: females which later had litter sisters in their group showed more positive social behavior than females which later no longer had litter sisters. During their first breeding season, females with litter sisters present generally started to breed earlier by an average of 14 days. A more favorable social environment might have possibly facilitated the earlier onset of breeding in females with present litter sisters by attenuating the negative consequences of stress.

Abstract: During a tong-term study on reproduction of the European rabbit (Oryctolagus cuniculus L.) that was carried out on a population living under semi-natural conditions, occasionally single pups per Litter were discovered being stuck in remnants of the foetal membranes. Here we describe this so far unknown phenomenon, quantify the occurrence, and investigate the consequences for the individual growth rate and for survival. Furthermore, we tested if maternal social rank and age were correlated with the occurrence of this phenomenon. Pups comprising the described adherence of the foetal membranes had tower growth rates than their unaffected titter siblings, and usually died during the nestling period or short after emergence above ground. Our findings point out that there was an individual predisposition of the mother for having affected titters. However, an impact of maternal social rank or age on the occurrence of this feature in their offspring was not supported by our data. Nevertheless, a pathological background also has to be considered as a possible cause. (c) 2007 Deutsche Gesellschaft fur Saugetierkunde. Published by Elsevier GmbH. All rights reserved.

Abstract: Spacing patterns of mammals are commonly assumed to be influenced by changes in food availability, resulting in shifts in diet. However, there is a lack of detailed case studies proving this relationship. We present here such a study carried out on two stone martens (Martes foina). We collected data on individual space use by radio telemetry, measured the diet by faecal analysis, and assessed changes in food availability of some main food items. Overall, changes in space use were paralleled by changes in diet, and might have been the result of changes in local food availability. In one case the animal stopped being active in a part of its home range when the high local availability of fruit (cherries) decreased in late summer. This decrease in cherries within its diet was mostly compensated for by increased ingestion of other kinds of fruit and of small mammals. In another case, the animal temporarily ventured into an area outside of its usual range of activity during winter when the availability of its seasonal staple food, earthworms, was low. In the new area, it fed on the available fruits and small mammals.

Abstract: Stress has been widely studied in different mammals, but the physiological stress reaction that the odour of a predator could induce in preys has not received much attention. Besides, not all the animals would respond to the same extent to a known stressor. We developed an experimental procedure with eleven naive European rabbits (Oryctolagus cuniculus) in order to determine the individual physiological response to the olfactory detection of a potential predator. The rabbits were housed singly in small enclosures with a concrete burrow system and food and water were available ad libitum. The animals followed a control trial, without odour, and an experimental trial where we confronted the rabbits with fox (Vulpes vulpes) odour. Furthermore, another sample of eleven rabbits followed a control procedure subjected to the same housing and handling procedures but without facing the predator odour. In order to assess the physiological response we analysed the concentration of glucocorticoid metabolites in the faeces of the rabbits. Therefore, everyday faecal samples were collected and analysed with an enzyme immunoassay in order to measure the corticosterone metabolites (CM), particularly, those metabolites with a 5 alpha-3 beta, 11 beta-diol structure. After validating the assay for wild rabbits, we found that the simulated presence of a predator (fox odour) in the enclosure resulted in an increase in faecal CM concentrations. However, the stressor did not affect all the animals in the same way. We found a general increase in the individual differences. In particular, males experienced a higher increase than females, though the overall response was similar for both sexes. To our knowledge this is one of the first attempts to analyse the assessment of the risk of predation by means of non-invasive methods.

Abstract: The recognition of predator odours is a well-known mechanism in many prey species which may lead to various behavioural and physiological responses. This has been shown for many mammal species under laboratory conditions, but efforts to validate the results in the field often have led to inconclusive results. We investigated the behavioural reactions and the physiological stress response of European rabbits (Oryctolagus cuniculus) to the odour of a mammalian predator (red fox, Vulpes vulpes) under semi-natural conditions. The study was conducted on a rabbit population living in an outdoor enclosure of 2 ha. We compared the rates of vigilance and exploration, the time allocated to self-directed behaviours, the home range sizes and the physiological responses of an experimental and a control group. Only animals from the experimental group were confronted with fox faeces. These animals increased their vigilance rate whereas the control animals did not respond. The increase did not differ between adult and subadult individuals. Furthermore, the experimental animals frequently approached the odour of the predator which might indicate an increase in investigative behaviour. Home-range size, feeding and other self-directed behaviours did not change in response to fox odour. Moreover, the animals of the experimental and the control group did not differ in serum corticosterone concentrations (measured after adrenocorticotrophic hormone challenge) that we determined in the beginning and in the end of the experiment. We suggest that the observed behavioural responses represent a low-cost strategy for lowering the individual risk of predation.

Abstract: The existence and consistency of individual behavioral types in response to challenging situations is of increasing interest in behavioral biology. In our study on European rabbits (Oryctolagus cuniculus), we (1) investigated correlations between social behavior during early development and responses to experimental stressors during later life, and (2) tested for consistencies in these responses across different situations. For this, we observed juveniles living in field enclosures in early summer and recorded agonistic and positive social interactions. In autumn, the animals were (a) introduced singly into a novel environment and were (b) confronted with predator (red fox Vulpes vulpes) odor. We recorded behavioral and physiological stress responses. In addition, we evaluated the predator odor test with an independent sample of animals. These latter results showed a correlation between the animals' behavioral and physiological response: Individuals, which reacted to the presence of fox odor by low scanning rates showed a high increase in serum corticosterone challenge concentrations, whilst the levels in high scanners remained stable. Overall, we found correlations among social behavior displayed during early development and behavioral responses in the two experimental tests, however the correlations between the different traits of social behavior and the responses during the two different experimental tests were not consistent. Animals which were involved in more agonistic interactions during their early development started to explore faster when entered into the novel environment. During the second test we found that rabbits which previously showed a higher frequency of positive social behavior responded to the presence of predator odor by more scanning. Moreover, the behavioral responses during both experimental tests were not correlated: fast explorers in the novel environment test did not show a more active response during the predator odor test. Due to this lack of consistent behavioral styles across both tests we conclude that the study fails to support the existence of domain-general behavioral phenotypes in European rabbits. (c) 2006 Elsevier Inc. All rights reserved.

Abstract: Environmental conditions frequently affect the reproduction of many mammal and bird species by modulating maternal body condition. In our long-term study of European rabbits, Oryctolagus cuniculus (L., 1758), we investigated the effects of winter weather conditions and body mass on reproductive performance and reproductive timing. Specifically, we tested whether winter temperature affects both reproductive timing and reproductive performance of female rabbits or whether females compensate for low body mass after winter by a shift in the timing of the onset of breeding. Winter body mass loss was higher in years with lower winter temperatures, and the onset of breeding was delayed after these conditions. However, mean size and mass of the first litter of each season and seasonal fecundity were not reduced after harsh winters. At the individual level, females with lower winter body mass started to reproduce later, but we did not find any effects on litter size and mass. In contrast, breeding body mass was a strong predictor of the females' reproductive performance. We also found high between-year variation in mean body mass in late winter but not in mean breeding body mass. In conclusion, our results suggest that the negative effects of winter weather on the body mass of females, which should potentially affect their reproductive performance, were compensated for by delaying the onset of breeding.

Abstract: Herbivores Living in seasonal environments commonly have to deal with reduced food availability and quality during the winter season. The present study investigated how European rabbits Oryctolagus cuniculus Living in a grassland habitat adapt their feeding behaviour to cope with this situation. Both adult and subadult animals markedly increased their feeding rates throughout the course of the winter, with the rates in subadults being generally higher. Nevertheless, both age classes showed a significant decline in body mass throughout the winter averaging 22.3% of the autumn mass in subadult and 9.7% in adult animals. In late winter, an increase in the faecal. sand content was found, indicating that the animals were feeding on ground-level plant parts. Measurements of nitrogen content of (1) grass leaves and stems and (2) ground-level sprouts and roots demonstrated a decrease in the food quality of grass Leaves and stems from early to late winter. In contrast, the nitrogen content of roots and ground-level sprouts remained stable. It can be speculated that the animals increasingly switched to ground-level plant parts as alternative food in the course of the winter in order to satisfy their needs for a sufficient source of nitrogen. (c) 2005 Deutsche Gesellschaft for Saugetierkunde. Published by Elsevier GmbH. ALL rights reserved.

Abstract: Animals show a variety of antipredator strategies in response to the presence of chemical cues from mammalian predators. Nevertheless, there is no general agreement as to whether recognition of predator odours is dependent upon experience. We conducted an experiment on European rabbits Oryctolagus cuniculus naive to any contact with predators and we investigated (1) whether they possessed a mechanism for the recognition of the odour of a predator, and (2) how they responded behaviourally and physiologically to that odour. We used fox Vulpes vulpes faeces as the source of the predator odour and sheep Ovis aries faeces as a nonpredator control odour. The experiments were conducted in small outdoor enclosures where the animals were kept singly. We recorded patterns of vigilance, activity and feeding, and changes in glucocorticoids and body mass. The rabbits showed a clear antipredator response to the presence of fox faeces, whereas they behaved neutrally in response to sheep odour. The response consisted of increased avoidance and vigilance while feeding and more investigation before feeding. Furthermore, the rabbits showed a physiological alarm response, that is, an increased responsiveness of their adrenocortical system and weight loss. However, the total activity budget, measured as time spent outside the burrow, the time spent feeding, and the amount of food ingested remained largely stable during the experiment. We conclude that rabbits recognised predator odours and that this recognition was independent of experience. (c) 2005 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Abstract: Foraging theory predicts that diet breadth should expand as food availability decreases. We tested this by looking at the winter browsing behaviour of the brown hare Lepus europaeus. We predicted selective feeding on different woody plant species, diet generalisation under increasingly severe winter conditions and a rank preference between the different food items. Following a period of severe winter conditions, we censused browsing marks of brown hares on woody plants at six sites situated at different altitudes (340-600 m a. s. l.) in Upper Franconia, Germany. We assumed that access to ground vegetation, which is the general diet of brown hares, was more restricted at sites with higher snow cover. The results provided support for all of our predictions: Feeding intensity varied strongly between the different plant species indicating selectivity of feeding. The number and also the percentage of browsed woody plant species was positively correlated with the attitude of the study site indicating a wider diet breadth in situations where Less food was available. On the basis of a rank model on the food choice of brown hares, which was evaluated by an independent data set, we conclude that brown hares show a rank preference with regard to different groups of woody plant species. Our findings support the assumption that food restricted hares increasingly include unfavourable, tow quality items into the diet.

Abstract: The survival probability of an individual may be limited by density-dependent mechanisms and by environmental stochasticity, but can also be modified by individual characteristics. In our study, we investigated over-winter survival of subadults of an enclosed European rabbit Oryctolagus cuniculus population in a temperate zone habitat over the period 1992-2002. We: (1) selected for appropriate models to explain individual variation in over-winter survival and the animals' autumn body mass, the latter was used as a measure of the individual pre-winter body condition; and (2) aimed to compare the sensitivity of the target variables on the realised variation of the factors considered. Model selection based on information theory revealed that individual over-winter survival was best explained by the combination of autumn body mass, winter temperature, population density and sex, where the probability of survival was higher in females than in males. According to this model, the probability of survival reacted most sensitively to variation in the autumn body mass and in winter temperature. Individual autumn body mass was best explained by the combination of the date of birth, population density, and weather conditions by means of the percentage of rainy days during the first 2 months after the animals had emerged above ground, where the autumn body mass was negatively related to the percentage of rainy days. The chosen model suggested that the autumn body mass reacted most sensitively to variation in the date of birth. Combining these models, we found that weather conditions during two different periods of time as well as population density, sex and the date of birth operated together to determine the probability of over-winter survival. In particular, the study points out the high impact of environmental stochasticity on over-winter survival: (1) by direct effects of winter temperature conditions, and (2) by the indirect action of weather conditions to which the animals were exposed during the early period of juvenile development.

Abstract: Density dependence of reproduction has generally been proposed to be caused by habitat heterogeneity and by the individual response of reproductive output. However, a further mechanism might generate density dependence of average reproductive rates. High density situations might be associated with a high proportion of first-season breeders which often show a principally lower reproductive performance. We tested for the existence of the latter mechanism as well as for density-dependent individual changes of reproductive effort in a population of European rabbits living in a homogeneous grassland habitat. The study was conducted over a period of eleven years. Overall, a strong relationship between mean reproductive rates and the breeding density of females was apparent. All necessary conditions for the presence of a density-dependent effect caused by age-dependent reproduction were fulfilled: Fluctuations of breeding density were paralleled by variations in the proportion of one-year-old females. These one-year-old, first-season breeders showed a consistently lower reproductive performance than older females, which might be caused by their lower body mass and their lower social rank. However, we also found strong evidence for density-dependent response of individual reproductive effort: Individual changes in fecundity over successive years were explained by changes in the breeding density of females. The results suggest that density dependence of reproduction in European rabbits is due to an interaction of age-dependent reproductive performance together with short-term fluctuations in breeding density, and a density-dependent, individual based response of reproductive rates. We further conclude that the lower reproductive performance of first-season breeders in age-structured animal populations may contribute substantially to interannual, and under particular circumstances to density-dependent variations of mean reproductive rates.

Abstract: We investigated whether predation by the minor grison (Galictis cuja, a small mustelid) played a key role in limiting a wild cavy population (Cavia magna), ultimately leading to its local extinction. Radio-telemetry and capture-mark-recapture techniques were used to estimate grison predation rates (kill rates), time-specific probabilities of apparent mortality (population loss rate), overall mortality and grison predation for the cavy population. Additionally, we present data on alternative prey species, grison diet and reproduction to show potential proximate mechanisms of grison predation on wild cavies. The predictions specified were mostly confirmed: (1) grison predation was responsible for almost 80% of the cavies killed by known predators; (2) grison predation probabilities paralleled those of overall mortality of cavies over time; and (3) also those of the apparent mortality of the population. Thus, the population dynamics and the local extinction of the cavy population were not due to emigration processes. (4) Grison predation rates were not density-dependent, but showed pronounced peaks during the austral summer. The grison mainly preyed on small mammals: two water-rat species and the wild cavies. When the availability of alternative prey decreased in summer, the grison appeared to specialise on cavies. The onset of grison reproduction was somewhat delayed in relation to the onset of cavy reproduction. The lack of alternative prey coincided with high grison food demands due to reproduction, leading to a very high predation pressure ultimately resulting in the local extinction of the cavy population. We conclude that grison predation was indeed the main factor driving changes of the cavy population studied and speculate why caviomorph rodents might be especially susceptible to local extinction processes.

Abstract: Notes on the feeding habits of the leopard in the alpine zone of Mount Kenya by H.G. Rödel 1, W.W.A. Scholze 2 and A. Paulsch 3 1 Department of Animal Physiology, University of Bayreuth, D-95440 Bayreuth, Germany 2 Steinbrecher Str. 15, D-38106 Braunschweig, Germany 3 Institut für Biodiversität - Netzwerk e.V., D-93049 Regensburg, Germany Email: 1 heiko.roedel@uni-bayreuth.de 2 w.scholze@daec.de 3 paulsch@biodiv.de CORRESPONDENCE: H.G. Rödel, Department of Animal Physiology, University of Bayreuth, D-95440 Bayreuth, Germany, fax: +49 (0)921 55 2794, Email: heiko.roedel@uni-bayreuth.de KEY WORDS: diet, leopard, Panthera pardus, Procavia johnstoni, rock hyrax, scat analysis The leopard Panthera pardus has the widest distribution of all large felids and occurs in a variety of environments (Myers 1976). Its diet is reported to be highly generalistic ranging from small mammals, reptiles and birds to large herbivores of more than twice its body mass (Kruuk and Turner 1967, Schaller 1972, Hoppe-Dominik 1984, Bailey 1993, Johnson et al. 1993, Karanth and Sunquist 1995, Hart et al. 1996, Edgaonkar and Chellam 2002). Little is known about the feeding habits of the leopard in high mountain ranges, however, studies in mountainous areas report high frequencies of small mammals in the leopard�s diet (Grobler and Wilson 1972, Smith 1978, Norton et al. 1986). We present data on the feeding habits of the leopard in the upper alpine zone of Mount Kenya, Republic of Kenya. During a 4-month period, we collected 44 leopard scats along valley bottoms, slopes, and on tracks passing over the ridges between the valleys. Additionally, we recorded leopard kills. Data were collected in 4 valleys of the upper western and northern slopes of Mount Kenya (Mackinder Valley, Höhnel Valley, Teleki Valley, and an unnamed valley between Hausberg and Teleki Valley; see map in Rödel et al. 2002). All of these U-shaped valleys radiate from the mountain peaks and are separated by steep and continuous ridges. Leopard scats were identified by their size, colour and shape. Scats < 1.50 cm in diameter, or of white colour were discarded because they might have been excreted by the serval Leptailurus serval or the spotted hyaena Crocuta crocuta. In many cases, we confirmed leopard scats from the close proximity of leopard tracks. We stored the scats separately in paper bags and air-dried them in the sun. In the lab, the scats were washed with water over a fine-mesh screen. Indigested remains such as hair and bones were extracted, dried and were identified with the aid of reference material in the Senckenberg Museum (Frankfurt, Germany). We counted the number of prey individuals per scat sample by the number of skulls, jaws or limb bones. This was only possible for ingested rodents and sometimes for rock hyrax Procavia johnstoni, whereas larger prey species were always counted as 1 individual per scat sample. Since the scats were of different ages and from different collection sites, we assumed that each scat sample always represented different prey individuals. We used 2 different parameters to assess the diet composition of the leopard: We (1) calculated the frequency of occurrence %F of the different prey species as the percentage of scats containing a particular prey item. We (2) assessed the relative biomass %M of each prey species by calculating the percentage of the number of individuals counted of a particular prey species times the mean body mass of this species on the total prey mass estimated. Mean body masses of different prey species were derived from the literature (Kingdon 1971, Coe and Foster 1972, Haltenorth and Diller 1984). Most of the scats were discovered on the bottom and slopes of the valley. However, we also found several droppings on tracks passing over the ridges at up to 4,600 m a.s.l., indicating that leopards in the upper alpine zone sometimes crossed between different valleys. Only 4 prey types were present in the scats collected (Table 1). The analysis revealed that rock hyrax were the leopard�s most frequent prey, followed by groove-toothed rats Otomys orestes/O. tropicalis. The differentiation between both rat species was not possible by means of hair structure or scull fragments. Rock hyrax also represented the bulk of the estimated relative prey biomass. This result confirms the findings of other studies in mountainous areas which also support the importance of small mammals, in particular of Procaviidae in the diet of the leopard (Grobler and Wilson 1972, Smith 1978, Norton et al. 1986). But also groove-toothed rats, which occur at high densities at the bottom of the valleys (Moreau 1944, Coe 1967; pers. obs. HGR & WWAS) seemed to be an important prey for the leopard. We found a high percentage of scats (29.5%) which consisted solely of remains of this rodent species. In 1 sample we also found remains of the African climbing mouse Dendromus insignis (Table 1); this small 15 g rodent is also a common inhabitant of the grassland area at the bottom of the upper valleys (Coe and Forster 1972). Another prey species, which we verified as a kill was the colobus monkey Colobus polykomos. We discovered remains of 1 individual (fur, gut and pieces of the head) in a cave at about 4,400 m a.s.l. together with leopard tracks and scats. The colobus, which is a resident forest species, has been reported at up to 3,000 m a.s.l. on Mount Kenya (Moreau 1944). There is only one publication citing the excursion of a colobus to the upper alpine zone of Mount Kenya. According to Young & Evans (1993), a dead �mummified� individual was recorded at 4,700 m a.s.l. by several mountaineering parties. However, it seems likely that in our case the leopard might have killed the monkey in a lower region and carried the prey to the cave, probably in order to feed its cubs. Dragging prey to a safe place is common behaviour in the leopard, and even movements over several kilometres have been documented (Corbett 1946, Stuart 1986). The only large mammal species (about 15 kg) which we verified in the diet of the leopard was the common duiker Sylvicapra grimma (Table 1). This prey species occurred infrequently in the scat samples, although it is reported to be common in the alpine zone of Mount Kenya. Bailey (1993) speculated that small ungulates such as duiker which are solitary, well dispersed, and consequently difficult to locate, might only occasionally be killed by leopards as long as other prey is abundant. We suppose that alternatively the high densities of rock hyrax provided a stable and sustainable food resource for the leopard which comprised a more favourable ratio between hunting effort and success. Our study confirmed that in some mountain zones of Kenya the leopard can apparently subsist on small mammals such as rodents and hyrax. However, we could not determine if the home ranges of leopards present in the upper alpine zone also included areas of lower altitude. Acknowledgements. � We are grateful to the Office of the President of the Republic of Kenya for granting permission for research and to the Kenyan Wildlife Service, especially to Bongo Woodley for providing facilities and assistance. We thank the members of our research group Bastian Eckert-Hetzel, Tim Förderer and Andreas Frisch for assistance in the collection of the samples. We are also indebted to Dieter Kock (Senckenberg Museum, Frankfurt) for providing essential help in the determination of bone fragments, and to Thomas Bodendorfer for providing helpful information in the field. Thanks to Adrienne Hogg, Cornelia Kraus, Raquel Monclús Burgoa and an anonymous reviewer for their helpful comments. Bibliography. BAILEY, T.N., 1993.- The African leopard: ecology and behavior of a solitary felid. Columbia University Press, New York. COE, M.J. and J.B. FOSTER, 1972.- The mammals of the northern slopes of Mt. Kenya. J. EANHS & Nat. Mus., 131: 1�18. COE, M.J., 1967.- The Ecology of the Alpine Zone of Mount Kenya. Junk Publishers, The Hague. CORBETT, J.E., 1946.- Man-eaters of Kumaon. New York: Oxford University Press. EDGAONKAR, A. and R. CHELLAM, 2002.- Food habits of the leopard, Panthera pardus, in the Sanjay Ghandi National Park, Maharashtra, India. Mammalia, 66: 353-360. GROBLER, J.H. and V.J. WILSON, 1972.- Food of the leopard Panthera pardus (Linn.) in the Rhodes Matopos National Park, Rhodesia, as determined by faecal analysis. Arnoldia, 5: 1-9. HALTENORTH, T. and H. DILLER, 1984.- Mammals of Africa including Madagascar. Collins, London. HART, J.A., M. KATEMBO and K. PUNGA, 1996.- Diet, prey selection and ecological relations of leopard and golden cat in Ituri Forest, Zaire. Afr. J. Ecol., 34: 364-379. HOPPE-DOMINIK, B., 1984.- �tude du spectre des proies de la panthère, Panthera pardus, dans le Parc National de Tai en Côte d�Ivoire. Mammalia, 48: 477-487. JOHNSON, K.G., W. WEI, D.G. REID and H. JINCHU, 1993.- Food habits of asiatic leopards (Panthera pardus fusea) in Wolong Reserve, Sichuan, China. J. Mamm., 74: 646-650. KARANTH, K.U. and M.E. SUNQUIST, 1995.- Prey selection by tiger, leopard and dhole in tropical rain forest. J. Anim. Ecol., 64: 439-450. KINGDON, J., 1971.- East African Mammals. Vol. I. Academic Press, London, New York. KRUUK, H. and M. TURNER, 1967.- Comparative notes on predation by lion, leopard, cheetah, and wild dog in the Serengeti area, East Africa. Mammalia, 31: 1-27. MOREAU, R.E., 1944.- Mount Kenya: A contribution to the biology and bibliography. J. EANHS & Nat. Mus., 18: 61-92. MYERS, N., 1976.- The leopard Panthera pardus in Africa. IUCN Monogr., no. 5. NORTON, P.M., A.B. LAWSON, S.R. HENLEY and G. AVERY, 1986.- Prey of the leopard in four mountainous areas of the south-western Cape Province. S. Afr. J. Wildl. Res., 16: 47-52. R�DEL, H.G., W.W.A. SCHOLZE and D. KOCK, 2002.- Diet of Mackinder�s eagle owl Bubo capensis mackinderi in the alpine zone of Mount Kenya. Afr. J. Ecol., 40: 283-288. SCHALLER, G.B., 1972.- The Serengeti lion. University of Chicago Press, Chicago. SMITH, R.M., 1978.- Movement patterns and feeding behaviour of the leopard in the Rhodes Mapotos National Park, Rhodesia. Carnivora, 1: 58-69. STUART, C.T., 1986.- The incidence of surplus killing by Panthera pardus and Felis caracal in Cape Province, South Africa. Mammalia, 50: 556-558. YOUNG, T.P. and M.R. EVANS, 1993.- Alpine vertebrates of Mount Kenya, with particular notes on the rock hyrax. J. EANHS & Nat. Mus., 82: 55-79. TABLE 1. � Frequency of occurrence (%F) of prey remains in leopard scats (n = 44) and the assessed proportion of prey biomass (%M). Prey species %F %M Rock hyrax Procavia johnstoni 65.9% 79.8% Groove-toothed rat Otomys orestes / O. tropicalis 52.3% 5.5% Climbing mouse Dendromus insignis 2.3% < 0.1% Common duiker Sylvicapra grimmia 2.3% 14.7%

Abstract: The diet of Bubo capensis mackinderi Sharpe in the alpine zone of Mt. Kenya was studied by analysing pellets collected from nesting and roosting sites in four different valleys. Overall, mammals comprised 97.4% of prey individuals and 98.9% of the ingested biomass. Rodents, mainly groove-toothed rats, were the owl's staple food in all four valleys, but rock hyrax, insectivores and birds were also consumed. Proportions of rock hyrax, rodents and insectivores did not differ between the valleys. Total dietary composition in the different valleys showed a high degree of overlap in proportions of main prey types averaging 93.2% in percentage of occurrence and 85.0% in percentage of biomass.

Abstract: Wild European rabbits of both sexes have separate linear rank orders, which are established and maintained by intensive fights. This paper presents data from a 14-year study (1987-2000) on the population physiology and behavioural ecology of wild rabbits living in a 22,000 M-2 enclosure and focuses on the relationship between social rank and reproduction in females. Group composition, social ranks, fecundity and reproductive success were known for all females (n=197) from the outset of their first reproductive season at an age of about 300 days until their death. The annual reproductive success of females was influenced to a large extent by their social rank. This depended on two effects of about equal strength: a higher fecundity of high-ranking females and a lower mortality of their offspring between birth and adulthood. The lifetime reproductive success of the females varied greatly. Only about 50% of all females had any reproductive success (range: on to nine adult offspring). The social rank achieved by the females during their first reproductive season substantially influenced their lifetime reproductive success: The mean reproductive lifespan and lifetime fitness of high-ranking females (ranks 1 and 2) was about 60% greater than that of lower-ranking females, although many of the latter also gained dominant positions in subsequent years.

Abstract: European female rabbits (Oryctolagus cuniculus) have evolved parsimony in the relationship towards their offspring. Lactating females nurse their litter immediately after parturition, but then leave the nest and will interact with their young only once per day, for a 5-minute nursing episode. Newborns are initially blind and deaf, and totally dependent of milk to survive. I nsomestic conditions as in the wild, they exhibit a typicalbehavioural repertoire controlled by olfaction and perioral somesthesios to locate the maternal nipples. Thus, chemosensory means of communication with the mother, based on previously learned odour cues and predisposed odour signals, promote high success in obtaining milk at least over postnatal days 10 to 15. Then audition and vision becomes functional and involved in social and feeding behaviour. The present paper aims to survey the behaviour of young rabbits between birth and weaning, and to offer indications on how it is controlled in the context of mither-offspring interactions by multiple sensory and environmental factors.

Abstract:

Abstract:

Abstract: The effects of low ambient temperature and of social factors on the physiological condition of subadult European wild rabbits (Oryctolagus cuniculus L.) during the winter season were studied in a population living under semi-natural conditions. Total serum protein, serum concentration of beta-hydroxybutyrate and body mass were monitored monthly and percentage of glycated haemoglobin was determined once in late winter. Social integration of subadults was assessed by direct observations. A close relationship between fluctuations of ambient temperature, serum protein levels and body mass was found. The results indicate that protein reserves rather than body lipids but were the important energy resource of subadult rabbits during the winter season. Negative effects on physiological parameters were closely related to higher mortality rates and to a shortened survival time respectively. The percentage of glycated haemoglobin and levels of serum protein were correlated with the degree of social integration whereas the relation to serum protein was only apparent in dispersers. I hypothesize that the negative physiological effects of the cold on subadults can be reduced either by mechanisms of social support and/or by thermoregulatory benefit.

Abstract:

Abstract: Distinguishing faeces of the stone marten from those of the pine marten is often a problem when both species occur sympatricly. We tested whether faeces from both species can be identified by thin-layer chromatography of faecal bile acids. Further the effects of diet composition and of food restriction on faecal bile acid concentration were evaluated by feeding experiments with two captured stone and pine martens and by assessing the diet of two wild stone martens. It was not possible to distinguish between faeces from stone and pine marten by their bile acid contents. All tested bile acids were detected in the faeces of both species. We also found no sufficient inter-specific differences of faecal bile acid concentration. The bile acid concentration in the faeces of both species was strongly influenced by diet composition and by the quantity of ingested food.

Abstract: Growth, development of body mass, and seasonal mortality of juveniles was studied in a population of European wild rabbits (Oryctolagus cuniculus L.) living under semi-natural conditions. Body mass at the age of twelve days was higher, and development of body mass and head length were on a higher level from late summer/autumn until the end of winter in juveniles born early in the reproductive season compared to animals born later. Mortality during nesting period was primarily caused by abiotic factors. We found mortality from the end of the nesting phase until autumn to be at least twice as high as during the nesting phase. Predation and diseases played an important part in this context. Only juveniles of the first two reproductive cycles survived until the onset of the following reproductive season. Beyond this, survival time of juveniles during autumn/winter was positively correlated with time of birth. We conclude that juveniles born early in the reproductive season had a higher probability of survival due to their better body condition.

Abstract: The feeding ecology of stone martens was studied in the Hakel, a wooded area surrounded by an agricul-tural region in Central Germany. Individual diets of five radio tracked stone martens were assessed by faecal analysis. In the study, we focused on mammalian prey and reciprocal effects on other ingested food items. In all analysed samples, which varied considerably in composition of diet during different seasons, the frequency of mammals ingested was higher than 20%. Rodents represented the major portion of mammals ingested. We also discovered local variations in the occurrence of small mammals in individual diets. By measuring food availability we could quantify stone martens´ resource utilization. For individual animals we proved preferences for fruits compared to small mammals and for small mammals compared to earthworms. Compared to Clethrionomys glareolus, Apodemus spec. were preferred by the stone martens. The results support the hypothesis, that foraging behaviour of stone martens is not only opportunistic and unspecialised; we can also conclude stone martens show food preferences.

Abstract:

Abstract:

Abstract: