Using high-resolution short-term location data to describe territoriality in Pacific martens

Katie M. Moriarty, Mark A. Linnell, Brandon E. Chasco, Clinton W. Epps, & William J. Zielinski

Solitary carnivores in the family Mustelidae are thought to exhibit pronounced intrasexual territoriality, defending space against competitors but tolerating members of the opposite sex. Although mustelids move long distances daily, how such movements reflect intrasexual territoriality is relatively unknown. We hypothesized that martens make regular movements around the boundaries of their territories and that territories typically would be stable across seasons and years. Consequently, we predicted that high-resolution movement data would reveal territorial boundaries within days to weeks. We collected movement data (from GPS collars) and long-term location data (from VHF collars) for 25 adult Pacific martens (Martes caurina) in 2 study areas (coastal and montane). We used GPS movement data to estimate utilization distributions and evaluate individual overlap and stability of territories between seasons, and compared those with annual home ranges from VHF locations. We also used incremental analysis to calculate how many days of movement data were required to fully describe a marten’s territory. Marten territories estimated from GPS movement data were indistinguishable from annual home ranges (spatial overlap,  X̅ ± SD, 0.99 ± 0.13, n = 9) and remained relatively stable year-round with some expansion during winter. Territories of same-sex neighbors overlapped < 2%. Our models suggested that an individual marten’s movements encompassed 95% of its territory within 2.25–14 days ( X̅  = 4.6 days); that time did not differ between study areas, sexes, or seasons. Location data with high spatial and temporal resolution could enable more precise estimates of territoriality in this and potentially other carnivore species, and illuminate hitherto unobservable behavioral differences across time and space.

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Katie M. Moriarty, Mark A. Linnell, Brandon E. Chasco, Clinton W. Epps, & William J. Zielinski. 2017. Using high-resolution short-term location data to describe territoriality in Pacific martens. Journal of Mammalogy 98(3):679-689.