Ecto- and Endoparasites of the Black Bear in Northern Wisconsin

[摘要] Black bears (Ursus americanus) were live-trapped and examined forectoparasites during the summers of 1974 and 1975 in northern Wisconsin.Nine bears were captured in 1974 and 104 bears (including 18 recaptures)were captured in 1975.Thirty-five (79.5%) of 44 captures from Clam Lake in 1975 carriedthe dog tick (Dermacentor variabilis Say, 1821), one (2.3%) the wintertick (Q. albipictus Packard, 1869), and one (2.3%) the black-legged tick(Ixodes scapularis Say, 1821) -- a new host and state record. Forty-five(75%) of 60 bears captured in Iron County in 1975 carried dog ticks.Dog ticks occurred on 76.9% of the 1975 captures and on 72.6% of all captures.Four (6.7%) of the bears captured in Iron County in 1975 hadmoderate to heavy infestations of a louse (Trichodectes pinguiseuarctidos Hopkins, 1954). Mange was observed on five (5.8%) bears capturedin 1975; two Demodex (Owen, 1843) mites were discovered in a scabsample. The black bear is a new recorded host for this mite. None of70 tissue samples was positive for Demodex. A flea was collected in1974 from an Iron County bear. Dental caries were present in nine (10.5%)bears captured in 1975. Periodontal disease was present in one (1.2%)Clam Lake bear.Twenty-eight viscera were obtained from hunter-killed bears duringthe 1974 and 1975 fall bear hunting seasons. Twenty-five (89.3%) intestinaltracts contained ascarid worms (Baylisascaris transfuga Rudolphi,1819). Fifty-nine (64.1%) of 92 fecal samples examined from live-trappedbears had B. transfuga eggs; 11 (39.3%) of 28 samples examined from viscerawere positive. An unidentified hookworm larva was recovered froaa bear captured in 1975. Adult filarial worms (Dirofilaria ursi Yamaguti, 1941) were found in two (7.1%) viscera. Seventeen (19.5%) of87 blood smears contained microfilariae. The broad fish tapeworm(Diphyllobothrium latum Linnaeus, 1785), reportedly common in humans andblack bears in the Lake Superior region earlier in this century, was absentfrom all viscera and fecal samples examined. The trichina worm(Trichinella spiralis Owen, 1835) was found in 6 (3.8%) of 163 Wisconsinbears in a study from 1970 to 1973; none was found in viscera or tissuesamples examined from this study.Tooth sectioning revealed an age range from 0.5 to 15.5 years forbears captured in 1975. The average age for males and females was 4.5and 6.02 years, respectively.

[发布机构] University of Wisconsin-Stevens Point, College of Natural Resources