Road mortality in Swedish mammals: results of a drivers' questionnaire

Abstract

We present new estimates on the national road kill for nine large and medium‐sized mammals in Sweden. Our estimates are based on 705 drivers' reports on the number of animals accidentally hit during individually chosen reference periods. During 1960–2000, a total of 881 animal‐vehicle collisions were reported based on 243.6 million driven kilometres, representing 0.37% of the overall mileage driven in Sweden during 1992, the mean reference year of all replies. The collision frequencies ranged from 0.07 incidents per million kilometres for medium‐sized mustelids, over 0.42 for badgers Meles meles to 1.11 for hares Lepus spp. Our data suggest that during 1992, 7,000–13,500 moose Alces alces, 43,500–59,000 roe deer Capreolus capreolus, 63,500–81,500 hares, 22,000–33,000 badgers and 6,500–12,500 red foxes Vulpes vulpes may have been killed on Swedish roads. Among these game species, the extrapolated nation‐wide road kill ranged between 7 and 97% of the average annual harvest, and between 1 and 12% of the assessed total populations in 1992. Our results are in agreement with other independent road kill estimates for Sweden. The data suggested an overall increase in the frequency of road kills over the past 40 years, which partly can be attributed to changes in traffic volume and wildlife population sizes (game bags). In most species, the estimated levels of nation‐wide road mortality are not alarmingly high, although local impacts may be significant. In badgers and hares, the ratio of the estimated road kill to the annual harvest increased two fold, suggesting a steady increase in the relative importance of road mortality. We conclude that interviews with drivers can provide a cheap and useful index of wildlife traffic mortality.