Effects of roads on badger Meles meles populations in south-west England

Roads have two major impacts on the landscape with respect to badger populations: (1) the imposition of barriers that reduce or prevent dispersal, and (2) the increased mortality caused by road traffic. Road traffic is the largest single cause of recorded death for badgers Meles meles in Britain. We used data collected by the Ministry of Agriculture, Fisheries and Food during the mid-1980s to quantify the effects of roads on badger populations in south-west England. The probability of badger fatalities per km were expressed as ratios of the number of road deaths per unit length of road for different classes of roads. The relationship between badger road deaths and traffic load appeared to be asymptotic. Despite large differences in traffic load and traffic flow on motorways, dual carriageways, class A and class B roads, they all had similar rates of badger fatalities per unit length of road, which were approximately six times greater than that for class C roads. These results suggest that high traffic loads may discourage badgers from attempting to cross major roads, and that these may therefore reduce movements between adjacent groups. Traffic levels on Britain's roads have already increased by 26% since these data were collected. As traffic loads increase further in the next century, the mortality and fragmentation effects of roads on badger populations locally are likely to become increasingly significant. (C) 1998 Elsevier Science Ltd. All rights reserved.