Factors affecting home range size of male Alpine ibex (Capra ibex ibex) in the Marmolada massif

In this study we investigated on the effects of different land cover types, meteorological conditions and age on the seasonal home range size of male Alpine ibex (Capra ibex ibex). The study was conducted in the Marmolada massif (Eastern Italian Alps). From September 2003 to the end of August 2009, 28 different male ibexes were regularly located by sightings and VHF radiotracking. We first analysed habitat selection performing a compositional analysis of log ratios and found that males positively selected grasslands all year long, likely for forage availability. We then estimated the cluster seasonal home ranges and modelled the logarithmic home range size with mixed linear models. We tested the effects of the individual and research year as random variables, season and age class as classification variables, and different combinations of percentage of grassland in the home ranges, slope, elevation and aspect as covariates. Model selection was based on the Akaike criterion. Inter-individual variability, research year and age class had no significant effects. The percentage of grassland within the home range and the slope of grasslands within the home range were the main determinants of home range size, explaining also the differences between seasons. Home range size in winter and spring was inversely correlated with the amount of snow depth. These results suggest that in winter spatial behaviour of male Alpine ibex is mostly influenced by snow while in the other seasons it is linked to resource exploitation: when forage is easily available ibexes did not need to seek out it by moving important distances.