Using the dead to monitor the living: Can road kill counts detect trends in mammal abundance?

Abstract

Counts of animal corpses resulting from road traffic collisions can give useful information on changes in animal abundance if there is a correlation between the population density of the species in neighbouring habitats and the number of road kills observed. Collection of data on mammal road casualties can be carried out by untrained volunteers; it can be collected across large areas; and it is cost effective in terms of time and expense. We carried out a study to determine if road casualty data can be used to monitor mammal abundance and distribution using one of the most commonly recorded road casualty species in the UK, the rabbit (Oryctolagus cuniculus), as an example. We found a direct relationship between the numbers of rabbit road casualties and the numbers living in the wider landscape. Nearly 60% of the deviance in the live rabbit density index could be explained using only rabbit road casualty, landclass group and traffic flow data. Therefore the use of road casualty data is a cost effective method of monitoring rabbits and, by implication, other species over a large area in the UK, and is a highly effective means of monitoring terrestrial mammals. © 2011, ALÖKI Kft., Budapest, Hungary.