Parturition site selection in moose (Alces alces): evidence for social structure

Abstract

Female natal philopatry has often been implicated as an important factor in moose ( Alces alces ) home range formation, with many populations showing behavioral evidence of sympatric home ranges among related individuals. However, previous genetic studies have failed to detect genetic subpopulation structure, leading to questions as to whether philopatry is a significant factor contributing to intra- and inter-population genetic structure. Here, we examine calving location data from radiomarked individuals ( n = 110) collected in 2 separate populations in Berners Bay and Gustavus, Alaska, to examine the extent to which genetic structure originating from philopatry is evident at fine spatial scales. When populations were combined, their overall relatedness correlogram was significant ( P < 0.001), with mean r = 0.079 between 0 km and 1.5 km ( P = 0.079). Additionally, 13% of the population shows significantly positive relatedness to their 4 nearest neighbors, with an overall average r = 0.19 of those focal individuals to their neighbors. We suggest that habitat structure, especially linear habitats (i.e., river valleys), or habitat bounded with barriers to dispersal, may be a factor in promoting the development of this structure. This study presents the 1st known evidence for fine-scale social genetic structure in moose and natal philopatry to calving locations in moose. In the context of natal philopatry within cervids, these findings identify several cervid-wide commonalities.