Abstract 190 – Andean bear tree selectivity for scent-marking in Ecuadorian cloud forests

Eva Filipczykova, Melanie Clapham, Russell C. Van Horn, Owen T Nevin, Jorge Luis
Armijos Barros, Aleš Vorel

Olfactory signaling is the most efficient mode of animal communication when the interval
between signaller and receiver is delayed. Scent-marking requires selective strategies to
increase the likelihood that these signals persist in the environment and are successfully
received. Bears are solitary, non-territorial carnivores, which scent-mark trees, substrate, and
other objects to communicate with conspecifics. Signallers place scent-marks on trees to
increase the detectability of their signals, possibly also to communicate their size and status.
While we are starting to better understand chemical signaling in bears of the northern
hemisphere, knowledge on tree selectivity for scent-marking and chemical signaling in general
of bears from tropical regions remains limited. We assessed scent-marking tree selectivity of
Andean bears, Tremarctos ornatus, in Ecuadorian cloud forests at two spatial scales: the
individual-tree level and at a local scale. We recorded characteristics of marked and unmarked
trees along bear trails (5.49 km in total) in the Eastern Cordillera of the Ecuadorian Andes, near
the Sumaco Biosphere Reserve. To decrease dimensionality and multicollinearity before
explanatory analyses, we performed Principal Component Analysis on data from 467 trees of 48
tree species. We then used Generalized Linear Models, model selection, and model averaging
to discover that Andean bears preferred rubbing leaning trees, aromatic tree species, and
hardwood trees with smaller and thicker leaves containing less nitrogen. Ten of 59 marking
sites contained clusters of marked trees, but site-level data did not indicate why bears marked
multiple trees at some sites but not others. We thus encourage further analyses of marked-tree
cluster sites and their relationship to productive food resources and reproduction, which might
present important communication hubs for ursids.