Dynamics of the colonization process in reintroduced populations of alpine marmot [Dynamique de la colonisation des populations réintroduites de la marmotte alpine].

Résumé

The project of marmot reintroduction in the Dolomiti Bellunesi National Park stated in 2006 and may 2007, 80 marmots (20 ind./year/area) ear-marked (by sex and family of origin) were released in two separated areas. We expose here data concerning the colonisation process carried out by animals released in 2006. The mean dispersion distance from release sites to settlement sites was 1047 m, greater in males (mean 1047 m, range 0-3300) than in females (mean 665 m, range 0-1295). The 61% of the settlement was composed by pairs, 33% by single males and 6% by a trio (marmots from different families of origin). The single males settled farther (1619 m) than coupled males (665 m). The 77.6% of all the possible « same-family composed » pairs occurred. Only one pair (same-family composed) bred successfully in the same year of release, but 87.5 % of the survived pairs bred the following year (mean litter size 4.6, range 3-7), included the one breeding at previous year too. We also recorded the reproduction of a single female (no-pair copulation), and the acceptance of the cubs by the males settled with her after the second release. Mortality rates of the animals released in 2006 was 39 % before the’ first winter, raising 53.6 after the second summer. The first summer mortality of animals released in 2007 was higher, probably because a greater predation by Golden Eagle. The populations density at last summer 2007 was 2.8 and 5.5 winter burrows/100 ha, and 9.8 and 7.8 marmots/100 ha respectively.