Research and Management of Black Bears in Crater Lake National Park, Oregon, 1974

Post Dump Closure Activity

Bear visitation to developed areas increased sharply following dump closures. Total property disturbance incidents increased from 5 in 1971 to 80 in 1972 (Table 1). Property disturbance incidents remained at a relatively high level during 1973, although seriousness of the problem decreased markedly and was reflected by a 74 percent decrease in property damage incidents for that year. The number of identified nuisance bears decreased from 14 in 1972 to 5 in 1973. Without harassment received by bears through study operations total incidents would undoubtedly have been even greater during both years.

Locations of bear sightings are reported for 1972-73 in Table 2. During the spring of 1972 bears confined their nuisance activities to the headquarters area, less than one and one-half miles from the closed Munson dumpsite. As the 1972 season progressed problem areas became more widespread. The headquarters area yielded the majority of bear sightings during 1973, primarily due to the persistent actions of one bear. Of 23 property damage incidents during 1972-73, 16 were reported from Mazama Campground. Despite the lack of bearproof garbage containers, no incidents were reported from the Lost Creek Campground. This is the smallest of the park’s three campgrounds and is the furthest from the Munson dumpsite (Fig. l). The percent of bear observations in wilderness areas increased from about three percent of the total sightings in 1972 to about 9 percent of the 1973 sightings.

Table 2. Locations of black bear sightings at Crater Lake National Park, 1972-73.

Numbers of property disturbance incidents peaked one month later in 1973 than in 1972 (Fig. 2). The 1973 curve corresponds closely with the usual pattern of park visitation; visitor numbers increase from a low level in June, peak during August, and drop off sharply after mid-September. An intensive trap-transfer program, mortalities, harassment to bears, and decreasing visitation all probably contributed to the decline in property disturbance incidents following July, 1972.

There were differences in the time of bear observations during the 1972-73 seasons (Fig. 3). Early in the season the majority of observations were made during daylight hours. From August through mid-September few bears were seen except at night. This trend to a more nocturnal habit was partly due to the decreased amount of human activity at night combined with an increase in food availability, ie. garbage cans are generally fullest in the evening, campgrounds are filled, and foodstuffs are unattended. Disturbance from daytime capture and tagging operations also caused bears to become more wary and nocturnal as the summer progressed.