Habitat use by two species of Mongolian marmots (Marmota sibirica and M. baibacina) in a zone of sympatry [Utilisation de l'espace par deux espèces de marmottes de Mongolie (Marmota sibirica and M. baibacina) dans une zone de sympatrie].

Résumé

The spatial segregation of Siberian marmots Marmota sibirica Radde, 1862 and grey marmots M. baibacina Katschenko, 1899 in the zone of contact in Mongolian Altai (47o 30' N, 90o 50'E) and habitat use by Siberian marmots at Aj Bogd Uul mountain (44o 43'N, 95o 10'E), where only this species occurs, were studied with the use of discriminant function analysis. In the zone of sympatry the Siberian marmots inhabit productive highland valleys, whereas the grey marmots occupy only tops of ridges reach of alpine vegetation. Three of the four localities where marmots intermediate in coloration and call were observed are characterized by suboptimal conditions (unproductive slopes of ridges). A pronouced niche shift towards the habitat of ridge tops and a light expansion of niche breadth were found in the allopatric populations of Siberian marmots.