Abstract 121 – New insights into Andean bear movement ecology across the Ecuadorian Andes

Francisco Castellanos, David Jackson, Stefano Mezzini, Jorge Brito, Armando
Castellanos

The Andean bear (Tremarctos ornatus) is a charismatic yet shy mammal that plays a key role in
maintaining ecosystems along the Andes. Ever since the first trapping and tagging of specimens
with VHF or GPS collars, research on their behavior has heavily relied on home range data as a
proxy to report behavior patterns, often drawn from biased datasets. This study reports the
first GPS-based investigation into the movement ecology and autocorrelated home range
estimates of a metapopulation consisting of 6 female and 3 male Andean bears spanning
various ages, inhabiting the northern and central Ecuadorian Andes. Over a decade, our
research and conservation project has tracked these animals for periods ranging from 5.5
months to 2.8 years, collecting a total of 26,884 unbiased GPS fixes. Remarkably, home range
sizes were considerably variable, ranging from 16.4 – 143.1 km2 in females, and 183.9 – 242.3
km2 in males. Continuous-time movement speeds showcased significant diurnal disparities,
fluctuating between 5.43 – 9.03 km/h during the day versus 0.85 – 2.70 km/h at night. Ongoing
analyses suggest nocturnal movements may be driven by environmental factors like
temperature and precipitation, though further investigation is needed to elucidate these
dynamics. These findings expand our knowledge of female home range occupancy, revealing
sizes up to 10 times larger, and 2 – 4 times larger in males than previously reported. These
differences may be related to the age of the animal, type of habitat, food availability, or estrus
cycles in females. The incorporation of this knowledge into the species’ biology and ecology will
foster protection efforts for this majestic and iconic mammal species native to South America.
Consecutively, safeguarding the protection of larger areas of paramos, cloud forests, and high
grasslands, all habitats that are increasingly threatened by deforestation and livestock farming.