98 research outputs found
Intra-sexual variability in feeding behaviour of a mountain ungulate: size matters
No full textMany studies comparing the behaviour of individuals of different genders or species showed that animal body mass and forage quality/quantity are key elements of the foraging ecology of herbivores. Since body mass could also influence the animal’s sensitivity to predation risk, its vigilance behaviour should consequently be affected. Alpine ibex (Capra ibex) is characterised by a strong dimorphism among males of different ages, thus representing an ideal case study for testing the Jarman-Bell principle, avoiding possibly misleading effects resulting from the comparison between different species or genders. We analysed the fine-scale foraging behaviour of male ibex in order to assess the effect of body mass and the effects of vegetation quality/quantity on both foraging and vigilance behaviour. Our results showed that smaller males were more selective than larger ones, on account of their lower capability of digesting plant. Smaller males scanned the environment more frequently than larger ones. Male ibex grazed more selectively in sites with high quality forage and their bite rate increased as forage biomass decreased. Vigilance frequency increased with increasing forage biomass as, under these circumstances, ibex are able to prolong anti-predator vigilance while chewing bites that have already been cropped. Our findings highlight the effects of body mass per se on both foraging and anti-predator behaviours in herbivores, thus supporting the Jarman-Bell principle. Foraging can arguably be considered a very flexible behaviour with high evolutionary relevance as it enables herbivores to optimally adjust their total energy intake under varying conditions of food resources
Sexual differences in the behavioural response to a variation in predation risk
No full textPredators may influence their prey populations not only through direct lethal effects, but also by causing behavioural changes. The natural expansion of the wolf (Canis lupus) into the Alps provided the rare opportunity to monitor the responses of a prey species to the return of a large predator. Density effects have rarely been considered in the study of antipredator strategies. We examined the effects of wolf recolonisa‐ tion and density modifications on group size and use of safe areas by Alpine ibex (Capra ibex) in Gran Paradiso National Park (Italy), where no large terrestrial predator has been present for about a century. We documented that, in a few years, the vari‐ ation in the factors affecting the landscape of fear caused significant modifications in ibex behavioural patterns that could not be accounted for by density changes only. Male groups decreased in size and moved closer to safer areas. The distance of fe‐ male groups from refuge sites, instead, was not affected, and their propensity to live in groups was scarcely modified. Behavioural modifications likely caused a reduction in nutrient intake in adult male ibex, as they necessarily used lower‐quality feeding patches. Our results showed that male and female ibex, which are characterised by a strong dimorphism, adopted different strategies to solve the conflicting demands of foraging efficiently and avoiding predators
Assessing the Impact of Capture on Wild Animals: The Case Study of Chemical Immobilisation on Alpine Ibex.
No full textThe importance of capturing wild animals for research and conservation projects is widely shared. As this activity continues to become more common, the need to assess its negative effects increases so as to ensure ethical standards and the validity of research results. Increasing evidence has revealed that indirect (physiological and behavioural) effects of capture are as important as direct risks (death or injury) and that different capture methodologies can cause heterogeneous effects. We investigated the influence of chemical immobilisation on Alpine ibex (Capra ibex): during the days following the capture we collected data on spatial behaviour, activity levels of both males and females, and male hormone levels. Moreover, we recorded the reproductive status of each marked female during the breeding seasons of 15 years. Then, by several a priori models we investigated the effects of the capture taking into account biological factors and changes in environmental conditions. Our results showed that chemical immobilisation did not affect either spatial behaviour (for both males and females) or male hormone levels, though both sexes showed reduced activity levels up to two days after the capture. The capture did not significantly affect the likelihood for a female to give birth in the following summer. Our findings highlighted the scarce impact of chemical immobilisation on ibex biology, as we detected alteration of activity levels only immediately after the capture if compared to the following days (i.e., baseline situation). Hence, the comparison of our findings with previous research showed that our methodology is one of the less invasive procedures to capture large mammals. Nonetheless, in areas characterised by high predator density, we suggest that animals released be carefully monitored for some hours after the capture. Moreover, researchers should avoid considering data collected during the first days after the manipulation in order to avoid biased information
Hunting seasons in relation to biological breeding seasons and the implications for the control or regulation of ungulate populations
No full text
Analysis of ecological factors able to affect horn size in yearling Alpine chamois: the role of the geological substrate in affecting horn growth.
No full textBehavioural response of two alpine ungulates after the recolonisation of the same predator.
No full textAlternative mating strategies and reproduction in Alpine ibex (Capra ibex): consequences of snowy winters.
No full textHabitat selection in adult males 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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