Abstract 215 – Camera trapping in southeast Peru shows no obvious evidence of seasonal habitat use by Andean bears

Russell Van Horn, Denisse Mateo Chero, Fernando Hancco Pacha, Flynn B
Vickowski, Ronald R Swaisgood, Mathias W Tobler, Megan A Owen

It is not well known what determines the Andean bear’s current habitat use. Thus, we cannot
predict its future habitat use, because Andean forest composition is shifting under climate
change. In addition, although seasonal habitat use has been predicted for Andean bears, there
have been few data to test this prediction. To begin addressing these questions, we installed
camera traps at 102 locations within the Manu Biosphere Reserve of SE Peru, descending from
treeline (~3750masl) to the Amazon rainforest (532masl). From 2016–2022, across 84,266
camera-days (c-d), we recorded 597 independent detections of 25 adult bears. Although 21%
of sampling effort (18,223 c-d) was below 1500 masl, <1% of bear detections (n=4) were
recorded at that elevation. To begin evaluating seasonal shifts in habitat use, we split data into
the dry season (May–Oct; 42,115 c-d) and the wet season (Nov–Apr; 42,151 c-d). We recorded
249 independent detections of bears in the dry season (0.59 detections/100 c-d), at an average
elevation of 2992 masl (839-3586, SD=664.7). We also recorded 348 independent detections of
bears in the wet season (0.83 detections/100 c-d), at an average elevation of 3031 masl (811-
3586, SD=628.5). Neither the rate of detections (p=0.49), nor their elevations (p=0.46), varied
between seasons. Thus, unless future individual-based analyses show the contrary, we see no
seasonal changes in elevation by bears in this landscape. The entire forested gradient above
1500masl appears to be year-round bear habitat, possibly due to the high diversity and
heterogeneity of these forests. In contrast, although lowland Amazonian forests are more
biodiverse, they appear unsuitable for bears, possibly due to the presence of jaguars, or due to
an unknown combination of abiotic factors. Without knowing what factors restrict these bears,
we cannot predict how their distribution will change, or suggest interventions. Future
collaborative large-scale analyses may guide mitigation plans.