Andean bear habitat use in the Oyacachi River Basin, Ecuador

One of the primary threats to Andean bear (Tremarctos ornatus) populations in Ecuador is conversion of bear habitat to human uses, resulting in habitat loss and fragmentation. To develop science-based conservation plans, information on the suitability and distribution of Andean bear habitat is critically needed. We studied habitat use in the 721-km² Oyacachi River Basin in the eastern Andes Mountains. We used bimonthly sign surveys along 1.6-km transects (N = 53) to determine habitat use. We recorded 549 and 202 locations of bear activity during 2000 and 2001, respectively; feeding signs were recorded most frequently (53.3%), followed by scats (19.6%), footprints (13.4%), hair (6.9%), tree marks (4.8%), trails (1.2%), and ground nests (0.8%). The combined total distance of surveyed transects for both years was 1,018 km with a corresponding sign encounter rate of 0.74/km. Use of the different vegetation types within the study area varied among the bimonthly sampling periods. Habitat suitability was calculated with a geographic information system (GIS) based on Mahalanobis distance (D²), a multivariate measure of dissimilarity, using 8 habitat variables and 437 bear locations. Model validity was confirmed by testing whether the D² values of 61 random locations in the Oyacachi River Basin were greater than those associated with 61 test locations. We used a cumulative frequency curve based on D¹ values associated with the 61 independent test locations to define 5 classes of habitat suitability, ranging from most used to avoided areas. The most suitable habitat class occupied 86.3 km² (11.9%) of the study area. The results of our study may be applied on a regional scale to define priority conservation areas for Andean bears in the eastern Andes Mountains of Ecuador. Our results indicate the usefulness of field-based studies combined with GIS and statistical analyses as a scientific basis for developing conservation strategies for Andean bears on a landscape scale.