title: Altered natal dispersal at the range periphery: The role of behavior, resources, and maternal condition.
abstract: Natal dispersal outcomes are an interplay between environmental conditions and individual phenotypes. Peripheral, isolated populations may experience altered environmental conditions and natal dispersal patterns that differ from populations in contiguous landscapes. We document nonphilopatric, sex-biased natal dispersal in an endangered small mammal, the Mt. Graham red squirrel (Tamiasciurus hudsonicus grahamensis), restricted to a single mountain. Other North American red squirrel populations are shown to have sex-unbiased, philopatric natal dispersal. We ask what environmental and intrinsic factors may be driving this atypical natal dispersal pattern. We test for the influence of proximate factors and ultimate drivers of natal dispersal: habitat fragmentation, local population density, individual behavior traits, inbreeding avoidance, competition for mates, and competition for resources, allowing us to better understand altered natal dispersal patterns at the periphery of a species' range. A juvenile squirrel's body condition and its mother's mass in spring (a reflection of her intrinsic quality and territory quality) contribute to individual behavioral tendencies for movement and exploration. Resources, behavior, and body condition have the strongest influence on natal dispersal distance, but affect males and females differently. Male natal dispersal distance is positively influenced by its mother's spring body mass and individual tendency for movement; female natal dispersal distance is negatively influenced by its mother's spring body mass and positively influenced by individual tendency for movement. An apparent feedback between environmental variables and subsequent juvenile behavioral state contributes to an altered natal dispersal pattern in a peripheral population, highlighting the importance of studying ecological processes at the both range center and periphery of species' distributions.
authors.affiliation: School of Natural Resources and the Environment Wildlife Conservation and Management University of Arizona Tucson AZ USA.
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Merrick
authors.affiliation: School of Natural Resources and the Environment Wildlife Conservation and Management University of Arizona Tucson AZ USA.
authors.forename: John L
authors.initials: JL
authors.lastname: Koprowski
keywords: Tamiasciurus hudsonicus grahamensis; behavioral phenotype; condition‐dependent dispersal; maternal effects; peripheral population; phenotype‐dependent dispersal