Abstract
Andean bears (Tremarctos ornatus) forage extensively on bromeliads (Puya spp.) across their range, although their selectivity for bromeliads is less understood. We report on foraging activity by Andean bears on two species of bromeliad, Puya leptostachya and Puya membranacea, in high elevation puna grasslands (3499-3806 m.a.s.l) within and near Manu National Park (MNP) in SE Peru. We established two ridgeline transects (inside and outside MNP) with perpendicular transects running downslope. We recorded whether bromeliad plants were foraged by Andean bears on four separate sampling occasions that included wet and dry seasons from July 2017 to August 2018. We observed foraging by Andean bears at 6.8% of the available individual plants spread across 16.7% of the available patches. We utilized Resource Selection Functions to evaluate the environmental factors influencing the selection of bromeliad patches by Andean bears for foraging. Andean bears showed selection for Puya leptostachya over Puya membranacea, preferring to forage during the dry season at higher density patches of younger vegetative-stage bromeliads, possibly due to the increased bioavailability of nutrients in the basal meristematic plant tissue the bears prefer to eat. Andean bears selected bromeliad patches growing on east-facing, steep, high-altitude slopes, in a band near the cloud forest edge, which likely reflected a combination of optimal growing conditions for the bromeliads and habitat selection by the bears. Observations of foraging on grassland bromeliads occurred almost exclusively within the boundaries of MNP, which may in part reflect bears avoiding cattle impacts outside of the park. Andean bears showed active behavioral selection for bromeliads within the puna grasslands, and we recommend that grassland buffers around the cloud forest should be considered as primary habitat in conservation management plans.