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Body weight and horn development in Alpine chamois, Rupicapra rupicapra (Bovidae, Caprinae)
No full textWith the aim of describing the trend in somatic development, especially the attainment of asymptotic body mass of Alpine chamois, Rupicapra rupicapra rupicapra, we recorded measurements (eviscerated body weight, length and height of horns) of 548 chamois harvested in 6 different valleys of the Piedmont region (Western Italian Alps), from 1984 to 1996. In male Alpine chamois, asymptotic mass was reached at 4.5-5.5 years of age, and after 4.5 years of age, the horns did not grow significantly between one year and the next. Females reached maximum body weight at about 3.5 years of age. Male chamois showed rapid early somatic development with consequent early development of sexual dimorphism. The mean body weights of males and females differed significantly from 3.5 years of age onwards, while horn size differed at as early as 1.5 years of age. Highest degree of sexual dimorphism in body weight (31.3 %) was found at 7.5 years of age. Male chamois reach asymptotic body mass in correspondence with first reproduction, while females mature before achieving asymptotic growth
Male Alpine chamois occupy territories at hotspots before the mating season
No full textUngulate mating systems vary broadly both between and within species. Studies on mating systems in different habitats can provide clues to the ecological factors determining this diversity. Despite its abundance in the European Alps and its importance as a game species, surprisingly little is known about the mating system of Alpine chamois Rupicapra rupicapra rupicapra. We tested the hypothesis that adult males first defend mating territories in late spring, when females segregate from males and well before the Nov. rut. In the Gran Paradiso National Park (north-western Italian Alps), adult males shared a winter range but occupied individual ranges in summer and early autumn. Males were more aggressive to each other in the summer than in the spring. A strong site fidelity from one year to the next was found for the summer and early autumn months. Those males that occupied the same territories both in the summer and during the rut (Nov.) appeared to be at hotspots, attractive to females during the rut because of reduced snow cover. Other males appeared to cluster around these hotspots during the rut. Territories that were first occupied during the summer were visited by more females than those that were not established until the rut began. Our results suggest that the mating system of this population of Alpine chamois consists of the early occupation of clustered mating territories. The early establishment of mating territories in areas frequented by females during the rut may lead to reproductive benefits for male chamois
Genetic variability and parasite resistance in a wild ungulate population
No full textMultilocus heterozygosity (MLH) is the standardized average observed heterozygosity among all microsatellite marker loci in one individual. MLH declines due to inbreeding, and negative associations between MLH and fitness reported in various vertebrate taxa are thought to reflect inbreeding depression (i.e. the reduction in fitness arising in inbred individuals). Here we report preliminary results on the relationships between MLH and parasite resistance in a population of free-ranging alpine ibex (Capra ibex) in the Gran Paradiso National Park (north-western Italian Alps). We used faecal counts of nematode eggs (FEC) as an indicator of parasite resistance. FEC analyses were performed on fresh faeces collected every two weeks over four summers (2000-2003) from individually marked male alpine ibex. MLH was estimated based on 32 microsatellite loci. No significant relationship between FEC and MLH was found. Statistical power was extremely low, despite sample size and number of loci was larger than in most other studies. The estimated needed sample size was way larger than what is normally possible to obtain in most studies on wild endagered populations. Information on inbreeding-fitness correlations can be vital to direct mangement and conservation efforts on endagered species. A sufficient sample size, however, may in many cases not be reachable in this kind of studies
Habitat selection in adult male of Alpine ibex, Capra ibex ibex
No full textHabitat use and selection of 14 Alpine ibex males were studied in the Gran Paradiso National Park. Alpine meadows were always overused and positively selected, because this habitat constituted an important food resource for the ibex. Even if rocks (30%) and stone ravines (22%) were the most frequented habitats in the study area, their use was lower than their availability because they offered few trophic resources. Pastures were used only in spring when the ibexes were looking for those sites just free from snow and with fresh vegetation. Stone ravines, where the ibexes rested in the hottest days, were most used in summer. Rocks were most used in winter: rock-faces are the only sites where the risk of avalanches is low and where it is still possible to find snow-free patches. Larch woods were especially used in winter and spring when it was still possible to find snow-free patches. The home range sizes proved to be influenced by the amount of Alpine meadows and rocks
Consequences of snowy winters on male mating strategies and reproduction in a mountain ungulate
No full text"Alternative mating tactics (AMTs) are intrasexual variants in mating behaviour of several species ranging from arthropods to mammals. Male AMTs coexist between and within populations. In particular, male ungulates rarely adopt just one tactic throughout their lifetime. Tactics commonly change according to internal factors (age, body size, condition) and external conditions (weather, resources, predation, animal density). However, the influence of weather has not yet been investigated in upper vertebrates. Such influence may be relevant in species whose rutting period occurs late in fall or in winter, when environmental conditions and the snow cover in particular may vary considerably. We detected two AMTs in Alpine ibex (Capra ibex) males: older and full-grown males mainly adopted the tending tactic, while younger males usually pursued an alternative one (coursing tactic). Weather was found to influence the use of AMTs by males: in snowy mating seasons, the coursing tactic was no longer used due to difficulties in moving through deep snow. In snowy rutting periods, males appeared to delay or even avoid mating activities and a decrease of births was reported in the second part of the following birth season. Snow cover may have a negative effect on population dynamics by reducing the recruitment and on population genetic variability, as a consequence of poorer mating opportunities. Studies on factors affecting mating behaviour and leading to a reduced availability of mates and a decrease in female productivity are especially relevant in species, like Alpine ibex, whose genetic variability is low.
Predation risk as a factor affecting sexual segregation in alpine ibex
No full textAlpine ibex (Capra ibex) are polygynous ungulates that exhibit extreme sexual dimorphism and segregation. To test the hypothesis that risk of predation plays a key role in the development of sexual segregation (habitat segregation) in this species, compositions and locations of groups of ibex were recorded from February 2003 to October 2004. Individual fixes of marked adult males and females in the Gran Paradiso National Park in Italy were collected monthly over a 4-year period (January 2000-December 2003). Distances were measured between each location and the nearest refuge area (rocky slopes), and between each location and the nearest source of disturbance (roads and hiking trails). Group size was not related to distances from refuge areas or from sources of disturbance, but sex, a e, and weaning played a key role in spatial segregation. During the period of rut, females 1 9 C, kept nearer to rocky slopes and further from hiking trails than males. The presence of young also influenced the spatial behavior of females: mothers made use of refuge areas more frequently and of areas near hiking trails less frequently than other females. In contrast, no difference between the spatial behaviors of pregnant and nonpregnant females was recorded in spring. Age played an important role in space use by males, but not by females. Young males (2-5 years) stayed closer to rocks than did middle-aged males (6-11 years), and both stayed closer to rocks than did adult males (> I I years). Adult males stayed closer to hiking trails than middle-aged males; likewise, the latter stayed closer to hiking trails than young males. Males stayed near areas with human presence, like]v because of good foraging opportunities. Although our findings do not exclude other explanations, they support the reproductive strategy-predation risk hypothesis. Moreover, predation risk was shown as an important factor leading to both sexual and age segregation in males
Seasonal variations of spatial behaviour in female Alpine ibex (Capra ibex ibex) in relation to climatic conditions and age
No full textThe spatial behaviour of female Alpine ibex Capra ibex ibex L. 1758, was analysed in Gran Paradiso National Park (Italy). Data were collected on 14 radio- collared females from September 2000 to August 2002, using radio-tracking and direct observations. Seasonal spatial behaviour was influenced by environmental conditions, in particular climatic factors. In the presence of thick snow cover, females significantly reduced winter home range sizes. Snow cover limited ibex mobility and reduced localization altitudes. Annual home range and winter home range sizes were inversely related to age. Temperature modified the use of space by females during summer. During the hottest summer females moved over larger ranges at higher altitudes. Annual home range sizes (mean 186.2 ha ± 71.7 in 2000 and 182.2 ha ± 70.0 in 2001) and seasonal home range sizes were significantly smaller than those of reintroduced populations, moreover they were smaller that those of males calculated in a close study area in Gran Paradiso National Park
Habitat selection in adult male of Alpine ibex, Capra ibex ibex
No full textHabitat use and selection of 14 Alpine ibex males were studied in the Gran Paradiso National Park. Alpine meadows were always overused and positively selected, because this habitat constituted an important food resource for the ibex. Even if rocks (30%) and stone ravines (22%) were the most frequented habitats in the study area, their use was lower than their availability because they offered few trophic resources. Pastures were used only in spring when the ibexes were looking for those sites just free from snow and with fresh vegetation. Stone ravines, where the ibexes rested in the hottest days, were most used in summer. Rocks were most used in winter: rock-faces are the only sites where the risk of avalanches is low and where it is still possible to find snow-free patches. Larch woods were especially used in winter and spring when it was still possible to find snow-free patches. The home range sizes proved to be influenced by the amount of Alpine meadows and rocks
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