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Jean-michel Gaillard - One of the best experts on this subject based on the ideXlab platform.
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is a proactive mum a good mum a mother s coping style influences early Fawn survival in roe deer
Behavioral Ecology, 2015Co-Authors: Chloe Monestier, Jean-michel Gaillard, Nicolas Morellet, Bruno Cargnelutti, Cecile Vanpe, A Mark J HewisonAbstract:Individual differences in behavior may strongly shape life-history trajectories. However, few empirical studies to date have investigated the link between behavioral traits and fitness, especially in wild populations. We measured the impact of coping style in female roe deer (Capreolus capreolus) on early survival of their offspring. Specifically, we expected offspring of proactive mothers, which should be more mobile and aggressive, to survive better than those of reactive females, which should be more passive and react less in stressful contexts. To test this prediction, we accounted for confounding effects of variation in early survival linked to habitat heterogeneity, as we also expected bed-site selection to impact Fawn survival. Fawn survival was highly dependent on the interaction between habitat use and the coping style of the mother. As expected, Fawns of proactive mothers survived better in open habitats. However, unexpectedly, Fawns of reactive mothers had the highest survival in closed habitats. Our findings provide clear evidence that interindividual differences in the coping style of the mother can markedly impact early offspring survival and, thereby, female fitness, in wild populations of mammals. Moreover, we provide evidence that fitness consequences of copying styles are habitat-dependent, providing a possible mechanism for the maintenance of within-population variation in behavior.
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High red deer density depresses body mass of roe deer Fawns
Oecologia, 2009Co-Authors: Emmanuelle Richard, Sonia Said, Jean-michel Gaillard, Jean-luc HamannAbstract:Many previous studies have pointed out that, when resources are limited, the potential for competition should be high among sympatric species that display overlaps in habitat and nutritional niches. However, reliable evidence of competition between red deer (Cervus elaphus) and roe deer (Capreolus capreolus) has not been yet reported for life history traits directly measuring performance such as body mass, reproduction, or survival. From long-term monitoring of deer populations in the reserve of La Petite Pierre (France), we measured the sex-specific responses of roe deer Fawn body mass to changes in red deer density after accounting for possible confounding effects of date of shooting, climatic conditions, and roe deer density. As expected under the hypothesis of competition, red deer density in a given year had a marked negative influence on body mass of roe deer Fawns born the same year and the following year. Fawn mass of roe deer males and females responded in similar ways to changes in red deer density. Our study provides the first evidence of a negative response of roe deer performance to high red deer density.
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density dependent responses of Fawn cohort body mass in two contrasting roe deer populations
Oecologia, 2006Co-Authors: Petter Kjellander, Jean-michel Gaillard, A Mark J HewisonAbstract:We investigated the influence of population density on juvenile body mass in two contrasting roe deer populations, in Sweden (Bogesund) and France (Chize), in which density was monitored for ≥15 years. We investigated the effect of population density and climatic conditions on cohort performance. We predicted that: (1) body mass of growing Fawns should be sensitive to environmental changes, showing marked between-year variation (i.e., cohort effects), (2) Fawns in the less productive (weakly seasonal, weakly predictable summer weather) habitat of Chize should show stronger density-dependent responses due to more severe food competition during summer than Fawns in the more productive (markedly seasonal, moderately predictable summer weather) habitat of Bogesund, and (3) Fawns at Bogesund should be heavier both in absolute terms and relative to their size than their conspecifics in Chize due to a higher degree of fat accumulation in northern environments. In both study sites we found marked cohort variation and clear effects of density, with body mass varying by as much as 29% over years. While neither summer nor winter climate influenced Fawn body mass at Bogesund, Fawns tended to be lighter after summers with high temperatures at Chize. In addition, Fawns were heavier after acorn mast years experienced in utero at Bogesund. As expected, the strength of the density-dependent response of Fawn body mass was greater at Chize than at Bogesund. For a given density, male Fawns were consistently heavier than females in both sites. Lastly, both sexes at Bogesund had higher absolute body mass and were larger for a given body size than in Chize. Our results clearly demonstrate that absolute density is a poor predictor of roe deer performance and supports the view that habitat quality has an overwhelming importance for determining Fawn body mass in roe deer populations.
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ecological correlates of home range size in spring summer for female roe deer capreolus capreolus in a deciduous woodland
Journal of Zoology, 2005Co-Authors: Sonia Said, Jean-michel Gaillard, Patrick Duncan, Nadine Guillon, Noel Guillon, Sabrina Servanty, Maryline Pellerin, Karen Lefeuvre, Cecile Martin, Guy Van LaereAbstract:Data on 22 radio-collared adult female roe deer Capreolus capreolus in the Chiz´ e forest were used to test whether their home-range size was influenced by resource availability and reproductive status. As roe deer females are income breeders and invest heavily in each reproductive attempt, they should be limited by energetic constraints. Thus it was expected that: (1) heavier females should have larger home ranges; (2) that home-range size should decrease with increasing vegetation biomass; (3) home-range size should increase with increasing reproductive effort (i.e. females with two Fawns at heel should have larger home ranges than those with one Fawn, which should have larger home range than females without Fawns). To test these predictions, variation in spring–summer homerange size was studied in 2001 and 2002, using 95% kernel home-range estimation. Results showed that females do not adjust their home-range size in response to body mass or age. Home-range size increased with increasing reproductive success, but the magnitude of the change varied over the period of maternal care. Finally, although their home-range size decreased with increasing plant biomass (slope =− 0.11, SE = 0.065), female roe deer at
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spatial variation in springtime food resources influences the winter body mass of roe deer Fawns
Oecologia, 2003Co-Authors: Nathalie Pettorelli, Jean-michel Gaillard, François Klein, Stéphane Dray, Daniel Chessel, Patrick Duncan, Andrew W. Illius, Nadine Guillon, Guy Van LaereAbstract:It is well established that the dynamics of mammalian populations vary in time, in relation to density and weather, and often in interaction with phenotypic differences (sex, age and social status). Habitat quality has recently been identified as another significant source of individual variability in vital rates of deer, including roe deer where spatial variations in Fawn body mass were found to be only about a tenth of temporal variations. The approach used was to classify the habitat into blocks a priori, and to analyse variation in animal performance among the predefined areas. In a fine-grained approach, here we use data collected over 24 years on 1,235 roe deer Fawns captured at known locations and the plant species composition sampled in 2001 at 578 sites in the Chize forest to determine the spatial structure at a fine scale of both vegetation and winter body mass of Fawns, and then to determine links between the two. Space and time played a nearly equal role in determining Fawn body masses of both sexes, each accounting for about 20% of variance and without any interaction between them. The spatial distribution of Fawn body mass was perennial over the 24 years considered and predicted values showed a 2 kg range according to location in the reserve, which is much greater than suggested in previous work and is enough to have strong effects on Fawn survival. The spatial distribution and the range of predicted body masses were closely similar in males and females. The result of this study is therefore consistent with the view that the life history traits of roe deer are only weakly influenced by sexual selection. The occurrence of three plant species that are known to be important food items in spring/summer roe deer diets, hornbeam (Carpinus betulus), bluebell (Hyacinthoides sp.) and Star of Bethlehem (Ornithogalum sp.) was positively related to winter Fawn body mass. The occurrence of species known to be avoided in spring/summer roe deer diets [e.g. butcher's broom (Ruscus aculeatus) and beech (Fagus sylvatica)], was negatively related to Fawn body mass. We conclude that the spatial variation in the body mass of Fawns in winter in this forest is as important as the temporal variation, and that the distribution of plant species that are actively selected during spring and summer is an important determinant of spatial variation in winter Fawn body mass. The availability of these plants is therefore likely to be a key factor in the dynamics of roe deer populations.
Guy Van Laere - One of the best experts on this subject based on the ideXlab platform.
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ecological correlates of home range size in spring summer for female roe deer capreolus capreolus in a deciduous woodland
Journal of Zoology, 2005Co-Authors: Sonia Said, Jean-michel Gaillard, Patrick Duncan, Nadine Guillon, Noel Guillon, Sabrina Servanty, Maryline Pellerin, Karen Lefeuvre, Cecile Martin, Guy Van LaereAbstract:Data on 22 radio-collared adult female roe deer Capreolus capreolus in the Chiz´ e forest were used to test whether their home-range size was influenced by resource availability and reproductive status. As roe deer females are income breeders and invest heavily in each reproductive attempt, they should be limited by energetic constraints. Thus it was expected that: (1) heavier females should have larger home ranges; (2) that home-range size should decrease with increasing vegetation biomass; (3) home-range size should increase with increasing reproductive effort (i.e. females with two Fawns at heel should have larger home ranges than those with one Fawn, which should have larger home range than females without Fawns). To test these predictions, variation in spring–summer homerange size was studied in 2001 and 2002, using 95% kernel home-range estimation. Results showed that females do not adjust their home-range size in response to body mass or age. Home-range size increased with increasing reproductive success, but the magnitude of the change varied over the period of maternal care. Finally, although their home-range size decreased with increasing plant biomass (slope =− 0.11, SE = 0.065), female roe deer at
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spatial variation in springtime food resources influences the winter body mass of roe deer Fawns
Oecologia, 2003Co-Authors: Nathalie Pettorelli, Jean-michel Gaillard, François Klein, Stéphane Dray, Daniel Chessel, Patrick Duncan, Andrew W. Illius, Nadine Guillon, Guy Van LaereAbstract:It is well established that the dynamics of mammalian populations vary in time, in relation to density and weather, and often in interaction with phenotypic differences (sex, age and social status). Habitat quality has recently been identified as another significant source of individual variability in vital rates of deer, including roe deer where spatial variations in Fawn body mass were found to be only about a tenth of temporal variations. The approach used was to classify the habitat into blocks a priori, and to analyse variation in animal performance among the predefined areas. In a fine-grained approach, here we use data collected over 24 years on 1,235 roe deer Fawns captured at known locations and the plant species composition sampled in 2001 at 578 sites in the Chize forest to determine the spatial structure at a fine scale of both vegetation and winter body mass of Fawns, and then to determine links between the two. Space and time played a nearly equal role in determining Fawn body masses of both sexes, each accounting for about 20% of variance and without any interaction between them. The spatial distribution of Fawn body mass was perennial over the 24 years considered and predicted values showed a 2 kg range according to location in the reserve, which is much greater than suggested in previous work and is enough to have strong effects on Fawn survival. The spatial distribution and the range of predicted body masses were closely similar in males and females. The result of this study is therefore consistent with the view that the life history traits of roe deer are only weakly influenced by sexual selection. The occurrence of three plant species that are known to be important food items in spring/summer roe deer diets, hornbeam (Carpinus betulus), bluebell (Hyacinthoides sp.) and Star of Bethlehem (Ornithogalum sp.) was positively related to winter Fawn body mass. The occurrence of species known to be avoided in spring/summer roe deer diets [e.g. butcher's broom (Ruscus aculeatus) and beech (Fagus sylvatica)], was negatively related to Fawn body mass. We conclude that the spatial variation in the body mass of Fawns in winter in this forest is as important as the temporal variation, and that the distribution of plant species that are actively selected during spring and summer is an important determinant of spatial variation in winter Fawn body mass. The availability of these plants is therefore likely to be a key factor in the dynamics of roe deer populations.
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early survival in roe deer causes and consequences of cohort variation in two contrasted populations
Oecologia, 1997Co-Authors: Jean-michel Gaillard, Patrick Duncan, Guy Van Laere, Jeanmarie Boutin, Daniel Delorme, Jeandominique LebretonAbstract:Time- and sex-specific summer survival of roe deer Fawns was estimated using capture-mark-recapture methods in two enclosed populations living in contrasting conditions. The population of Trois Fontaines (eastern France) was roughly constant in size throughout the study period, while in Chize (western France), the population experienced frequent summer droughts and numbers decreased continuously during the study. Early survival of Fawns was low and highly variable over the years at both Chize and Trois Fontaines, and demonstrated marked variations between cohorts that need to be taken into account when modelling roe deer population dynamics. In Trois Fontaines, Fawn survival was positively correlated with early body growth and total rainfall in May and June. In Chize, Fawn survival decreased with increasing density and tended to increase with increasing rainfall in May and June and adult female body mass. These factors explained more than 75% of the variability in early survival observed in both populations. Variation between cohorts had different consequences for the two populations. At Trois Fontaines, cohort variation was limited to a numerical effect on early survival. However at Chize, cohort variation was long-lasting and affected the phenotypic quality of survivors at later ages, and thereby future survival and breeding abilities (both numerical and quality effects). Male and female Fawns had similar survival over their first summer in both populations. This result contrasts with the lower survival of young males often observed in ungulates. Two ultimate causes can be proposed to account for the low and variable survival of roe deer Fawns over the first summer: the high energy expenditures incurred by does during each breeding attempt and/or the low absolute body size of newborn roe deer Fawns.
Reidar Andersen - One of the best experts on this subject based on the ideXlab platform.
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when a generalist becomes a specialist patterns of red fox predation on roe deer Fawns under contrasting conditions
Canadian Journal of Zoology, 2008Co-Authors: Manuela Panzacchi, John D. C. Linnell, John Odden, Morten Odden, Reidar AndersenAbstract:The red fox (Vulpes vulpes (L., 1758)) functional response to roe deer (Capreolus capreolus (L., 1758) Fawn density was investigated in two Norwegian study areas characterized by a 26-fold difference in prey density and contrast- ing habitat characteristics. In the southern area, characterized by a fragmented agricultural landscape and high prey den- sity, red fox consumption rates were closer to the specialist end in the specialist-generalist continuum of feeding habits. Conversely, in the northern area, dominated by boreal forest and with low prey density, the foxes displayed a type-III functional response typical of archetypal generalist predators. We suggest that differences in the predators' feeding habits reflect differences in prey profitability, which was much higher in the southern area owing to higher prey density and to the openness of the landscape that both favour the hunting of roe deer Fawns. Different functional responses produced dif- ferent predation rates (25% for the southern area and 13% for the northern area) and different temporal patterns (highest predation risk for Fawns born at the beginning or at the end of the birth season). Even though the understanding of a pred- ator's functional response is crucial for interpreting predation rates and patterns, much remains to be understood regarding its plasticity in different ecological settings. In the Fawn-fox system, this might be the key factor in addressing unsolved questions regarding the adaptive value of reproductive synchrony as an antipredator strategy. Given the flexibility of the functional response and the resulting different impacts of predation with respect to birth synchrony, we suggest that repro- ductive synchrony evolved primarily in response to habitat seasonality and not as an antipredator strategy. Finally, our re- sults contribute to the debate on the additive or compensatory nature of neonatal predation. Resume´ : Nous etudions la reponse fonctionnelle du renard roux (Vulpes vulpes (L., 1758)) au chevreuil d'Europe (Cap-
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individual access to preferred habitat affects fitness components in female roe deer capreolus capreolus
Journal of Animal Ecology, 2004Co-Authors: Erlend B Nilsen, John D. C. Linnell, Reidar AndersenAbstract:Summary 1. Many studies have reported variation in life-history traits and reproductive success within populations. One potential source for the reported variation is fine-scale spatial variation in habitat quality. 2. In this study the effects of differences in home-range quality on individual fitness were investigated in a roe deer population in an agricultural‐woodland mosaic landscape in central Norway. 3. Compositional analysis revealed that woodland was the most preferred habitat: its availability was therefore used as an index of home-range quality. 4. It was found that the quality of the does’ winter home-range affected Fawn production in the subsequent spring, as females with greatest availability of preferred habitat during winter produced the larger litters the subsequent spring. 5. Furthermore, the winter weights of the Fawns seemed to be affected by home-range quality in a complex way. First, home-range quality in the prenatal winter seems to influence the birthdate and in turn the weight of the Fawns in August. Also there was an immediate effect of the quality of the home-range that the Fawns occupied during the postnatal winter. 6. These results are not consistent with the ideal free distribution theory, suggesting that the mechanisms for roe deer spacing behaviour should be re-examined.
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Selection of bed-sites by roe deer Capreolus capreolus Fawns in a boreal landscape
Wildlife Biology, 1999Co-Authors: John D. C. Linnell, Patricia Nijhuis, Ivonne Teurlings, Reidar AndersenAbstract:Bed-site selection by 19 radio-collared roe deer Capreolus capreolus Fawns from seven family groups was studied during June-July 1998 in southeastern Norway. The habitat consisted of small agricultural fields surrounded by industrially exploited boreal forest. Within the forest, Fawns selected bed-sites that offered greater concealment, higher vegetation and more canopy cover than random sites. No such selection was evident within the homogenous pasture on the fields. Bed-sites in fields offered greater concealment than those in the forest, where there were no detectable differences between stand age classes. Compositional analysis revealed a significant preference for bed-sites to be located in forest, although fields and bogs were often used. Within the forest, stands of all age classes were used. The broad use of habitats may either reflect that habitats were equally good, or it may be a strategy to increase the area a predator has to search in order to find a Fawn.
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the effects of sex time of birth and habitat on the vulnerability of roedeer Fawns to red fox predation
Canadian Journal of Zoology, 1996Co-Authors: Ronny Aanes, Reidar AndersenAbstract:Red fox (Vulpes vulpes) predation on roe deer (Capreolus capreolus) Fawns was studied using radiotelemetry techniques on an island in central Norway. Red foxes killed 48% of the monitored roe deer Fawns within 60 days of birth, and mortality from other factors constituted only a minor part (5%) of the total mortality. The predation rate was lower in first week of life than during the subsequent 3 weeks. Male roe deer Fawns were four times more susceptible to red fox predation than female Fawns. We argue that these results reflect differences in behaviour between the sexes. There were some indications that time of birth may be important in determining vulnerability of Fawns to red fox predation, with Fawns born during the birth peak suffering more predation than Fawns born outside the peak. The type of habitat a roe deer Fawn used appeared to influence the probability of being killed by a red fox, and our results supported the hypothesis that hiding is a strategy to avoid predation in dense habitats. Fawns...
Susan Lingle - One of the best experts on this subject based on the ideXlab platform.
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the effect of terrain and female density on survival of neonatal white tailed deer and mule deer Fawns
Ecology and Evolution, 2016Co-Authors: Maegwin Bonar, Micheline Manseau, Justin Geisheimer, Travis Bannatyne, Susan LingleAbstract:Juvenile survival is a highly variable life-history trait that is critical to population growth. Antipredator tactics, including an animal's use of its physical and social environment, are critical to juvenile survival. Here, we tested the hypothesis that habitat and social characteristics influence coyote (Canis latrans) predation on white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus) Fawns in similar ways during the neonatal period. This would contrast to winter when the habitat and social characteristics that provide the most safety for each species differ. We monitored seven cohorts of white-tailed deer and mule deer Fawns at a grassland study site in Alberta, Canada. We used logistic regression and a model selection procedure to determine how habitat characteristics, climatic conditions, and female density influenced Fawn survival during the first 8 weeks of life. Fawn survival improved after springs with productive vegetation (high integrated Normalized Difference Vegetation Index values). Fawns that used steeper terrain were more likely to survive. Fawns of both species had improved survival in years with higher densities of mule deer females, but not with higher densities of white-tailed deer females, as predicted if they benefit from protection by mule deer. Our results suggest that topographical variation is a critical resource for neonates of many ungulate species, even species like white-tailed deer that use more gentle terrain when older. Further, our results raise the possibility that neonatal white-tailed Fawns may benefit from associating with mule deer females, which may contribute to the expansion of white-tailed deer into areas occupied by mule deer.
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Lingle_Bonar_DryadDataDescription
2016Co-Authors: Susan Lingle, Maegwin BonarAbstract:This Microsoft Word file describes data columns used in two data files: File 1 filename = Fawn_Sightings_Raw_Data which has data for individual sightings of deer Fawns. File 2 = Fawn_Summary_Data.xlsx has a summary row for each Fawn
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Altruism and recognition in the antipredator defence of deer: 2. Why mule deer help nonoffspring Fawns
Animal Behaviour, 2007Co-Authors: Susan Lingle, W. Finbarr Wilson, Drew Rendall, Randy W. Deyoung, Sergio M. PellisAbstract:Both white-tailed deer, Odocoileus virginianus, and mule deer, O. hemionus, females defend Fawns against coyotes, Canis latrans, but only mule deer defend nonoffspring conspecific and heterospecific Fawns. During a predator attack, females may have to decide whether to defend a Fawn while having imperfect information on its identity obtained from hearing a few distress calls. Although imperfect recognition can influence altruistic behaviour, few empirical studies have considered this point when testing functional explanations for altruism. We designed a series of playback experiments with Fawn distress calls to test alternative hypotheses (by-product of parental care, kin selection, reciprocal altruism) for the mule deer’s defence of nonoffspring, specifically allowing for the possibility that females mistake these Fawns for their own. White-tailed deer females approached the speaker only when distress calls of white-tailed deer Fawns were played and when their own Fawn was hidden, suggesting that Fawn defence was strictly a matter of parental care in this species. In contrast, mule deer females responded similarly and strongly, regardless of the caller’s identity, the female’s reproductive state (mother or nonmother) or the presence of their own offspring. The failure of mule deer females to adjust their responses to these conditions suggests that they do not defend nonoffspring because they mistake them for their own Fawns. The lack of behavioural discrimination also suggests that kin selection, reciprocal altruism and defence of the offspring’s area are unlikely to explain the mule deer’s defence of nonoffspring. We identify causal and functional questions that still need to be addressed to understand why mule deer defend Fawns so indiscriminately.
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interspecific variation in antipredator behaviour leads to differential vulnerability of mule deer and white tailed deer Fawns early in life
Journal of Animal Ecology, 2005Co-Authors: Susan Lingle, Sergio M. Pellis, Finbarr W WilsonAbstract:Summary 1 Ungulates are viewed as being highly susceptible to predation during the initial weeks or months of life. Yet aggressive defence by adult females is common in many ungulates and has the potential to reduce the vulnerability of the young significantly. 2 We observed naturally occurring predatory encounters between coyotes Canis latrans Say and deer Fawns to test the hypothesis that a difference in aggressive defence leads to the differential vulnerability of mule deer Odocoileus hemionus Rafinesque and white-tailed deer O. virginianus Zimmermann Fawns in summer, when Fawns are 0–14 weeks in age. Whitetail Fawns suffer higher levels of coyote predation than do mule deer Fawns at that time. The two species of deer are similar in size, but are known to differ in their antipredator behaviour in winter when Fawns are older. 3 Coyotes were less likely to attack mule deer than whitetail Fawns they encountered, and were less likely to kill mule deer than whitetail Fawns they attacked. 4 The presence of a mule deer, but not a whitetail, female with a Fawn deterred coyotes from attacking the Fawn. Once attacked, Fawns of both species were less likely to be killed when females defended them, but mule deer females were far more likely to defend Fawns. 5 Mule deer females defended Fawns that were not their own offspring, including heterospecific Fawns. Mule deer Fawns were more likely to be defended if they had a larger number of females nearby when encountered. These observations raise the possibility that mule deer, and even whitetail, Fawns may have improved survival in areas with higher densities of mule deer females. 6 These results show that higher levels of defence by mule deer females reduced the vulnerability of mule deer Fawns, contributing to the lower predation rates reported for mule deer than for whitetail Fawns of this age group.
Patrick Duncan - One of the best experts on this subject based on the ideXlab platform.
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ecological correlates of home range size in spring summer for female roe deer capreolus capreolus in a deciduous woodland
Journal of Zoology, 2005Co-Authors: Sonia Said, Jean-michel Gaillard, Patrick Duncan, Nadine Guillon, Noel Guillon, Sabrina Servanty, Maryline Pellerin, Karen Lefeuvre, Cecile Martin, Guy Van LaereAbstract:Data on 22 radio-collared adult female roe deer Capreolus capreolus in the Chiz´ e forest were used to test whether their home-range size was influenced by resource availability and reproductive status. As roe deer females are income breeders and invest heavily in each reproductive attempt, they should be limited by energetic constraints. Thus it was expected that: (1) heavier females should have larger home ranges; (2) that home-range size should decrease with increasing vegetation biomass; (3) home-range size should increase with increasing reproductive effort (i.e. females with two Fawns at heel should have larger home ranges than those with one Fawn, which should have larger home range than females without Fawns). To test these predictions, variation in spring–summer homerange size was studied in 2001 and 2002, using 95% kernel home-range estimation. Results showed that females do not adjust their home-range size in response to body mass or age. Home-range size increased with increasing reproductive success, but the magnitude of the change varied over the period of maternal care. Finally, although their home-range size decreased with increasing plant biomass (slope =− 0.11, SE = 0.065), female roe deer at
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spatial variation in springtime food resources influences the winter body mass of roe deer Fawns
Oecologia, 2003Co-Authors: Nathalie Pettorelli, Jean-michel Gaillard, François Klein, Stéphane Dray, Daniel Chessel, Patrick Duncan, Andrew W. Illius, Nadine Guillon, Guy Van LaereAbstract:It is well established that the dynamics of mammalian populations vary in time, in relation to density and weather, and often in interaction with phenotypic differences (sex, age and social status). Habitat quality has recently been identified as another significant source of individual variability in vital rates of deer, including roe deer where spatial variations in Fawn body mass were found to be only about a tenth of temporal variations. The approach used was to classify the habitat into blocks a priori, and to analyse variation in animal performance among the predefined areas. In a fine-grained approach, here we use data collected over 24 years on 1,235 roe deer Fawns captured at known locations and the plant species composition sampled in 2001 at 578 sites in the Chize forest to determine the spatial structure at a fine scale of both vegetation and winter body mass of Fawns, and then to determine links between the two. Space and time played a nearly equal role in determining Fawn body masses of both sexes, each accounting for about 20% of variance and without any interaction between them. The spatial distribution of Fawn body mass was perennial over the 24 years considered and predicted values showed a 2 kg range according to location in the reserve, which is much greater than suggested in previous work and is enough to have strong effects on Fawn survival. The spatial distribution and the range of predicted body masses were closely similar in males and females. The result of this study is therefore consistent with the view that the life history traits of roe deer are only weakly influenced by sexual selection. The occurrence of three plant species that are known to be important food items in spring/summer roe deer diets, hornbeam (Carpinus betulus), bluebell (Hyacinthoides sp.) and Star of Bethlehem (Ornithogalum sp.) was positively related to winter Fawn body mass. The occurrence of species known to be avoided in spring/summer roe deer diets [e.g. butcher's broom (Ruscus aculeatus) and beech (Fagus sylvatica)], was negatively related to Fawn body mass. We conclude that the spatial variation in the body mass of Fawns in winter in this forest is as important as the temporal variation, and that the distribution of plant species that are actively selected during spring and summer is an important determinant of spatial variation in winter Fawn body mass. The availability of these plants is therefore likely to be a key factor in the dynamics of roe deer populations.
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early survival in roe deer causes and consequences of cohort variation in two contrasted populations
Oecologia, 1997Co-Authors: Jean-michel Gaillard, Patrick Duncan, Guy Van Laere, Jeanmarie Boutin, Daniel Delorme, Jeandominique LebretonAbstract:Time- and sex-specific summer survival of roe deer Fawns was estimated using capture-mark-recapture methods in two enclosed populations living in contrasting conditions. The population of Trois Fontaines (eastern France) was roughly constant in size throughout the study period, while in Chize (western France), the population experienced frequent summer droughts and numbers decreased continuously during the study. Early survival of Fawns was low and highly variable over the years at both Chize and Trois Fontaines, and demonstrated marked variations between cohorts that need to be taken into account when modelling roe deer population dynamics. In Trois Fontaines, Fawn survival was positively correlated with early body growth and total rainfall in May and June. In Chize, Fawn survival decreased with increasing density and tended to increase with increasing rainfall in May and June and adult female body mass. These factors explained more than 75% of the variability in early survival observed in both populations. Variation between cohorts had different consequences for the two populations. At Trois Fontaines, cohort variation was limited to a numerical effect on early survival. However at Chize, cohort variation was long-lasting and affected the phenotypic quality of survivors at later ages, and thereby future survival and breeding abilities (both numerical and quality effects). Male and female Fawns had similar survival over their first summer in both populations. This result contrasts with the lower survival of young males often observed in ungulates. Two ultimate causes can be proposed to account for the low and variable survival of roe deer Fawns over the first summer: the high energy expenditures incurred by does during each breeding attempt and/or the low absolute body size of newborn roe deer Fawns.
