The effect of changes in traffic flow on mammal road kill counts

Abstract

It is estimated that one million wild animals are killed on UK roads each year and these casualties are potentially a valuable source of data relating to the size and distribution of populations. Road kill surveys have the potential to form the basis of a nationwide mammal monitoring scheme with multi-species coverage and excellent area sampling. However it has been argued that road casualty counts cannot be used to monitor population change because variation in the number of road deaths is related more to variation in traffic flow than to population density. We used rabbit and hedgehog as study species to examine if there was a relationship between traffic flow and road kill counts. We found no correlation between changes in traffic flow and road counts of hedgehog or rabbit. We conclude that a decrease in road kill counts of these species is highly likely to represent a decrease in absolute abundance and would therefore be a good index with which to monitor population decline.