HABITAT SELECTION AND HOME RANGES OF RIVER OTTERS IN A MARINE-ENVIRONMENT - EFFECTS OF THE EXXON-VALDEZ OIL-SPILL

We studied habitat selection and home ranges of river otters (Lutra canadensis) living along the coastlines of Prince William Sound, Alaska, following the Exxon Valdez oil spill in late March 1989. Deposition of feces by otters at latrine sites that were heavily oiled was significantly less than for nonoiled sites in Herring Bay in June and July, but not during August 1989. Finer-scale measurements of habitat showed selection differed significantly on oiled (Herring Bay) and nonoiled (Esther Passage) study areas in 1990; otters selected steeper tidal slopes and sites with larger rocks on oiled than on nonoiled areas, based on characteristics of latrines and random sites. We believe otters avoided shallower slopes and protected areas with smaller rocks and gravel where oil persisted the longest. Thus, differences in habitat selection ostensibly were the result of a reduction in habitat availability caused by oil contamination. Otters on both study areas strongly selected old-growth forest; commercially logged areas in Esther Passage had no otter latrines. River otters on both areas also selected vegetated slopes (approaches to latrine sites) that were less steep. Home ranges of otters were about twice as large on the oiled area as on the nonoiled area, again suggesting that habitat for otters was reduced as a result of the oil spill. These outcomes were detected >1 year after the oil spill and suggest that there may be chronic effects of the oil spill on river otters.