Main content area

Temporal variation in the number of car-killed red deer Cervus elaphus in Norway

Mysterud, Atle
Wildlife biology 2004 v.10 no.3 pp. 203-211
Cervus elaphus, North Atlantic Oscillation, accidents, autumn, climate, coasts, harvesting, models, population density, population growth, population size, road kills, summer, temporal variation, traffic, winter, Norway
Determining the factors causing variation in traffic accidents both in space and time are important for management, as it can help in designing mitigation efforts. The annual harvest of red deer Cervus elaphus in Norway has increased from 2,695 in 1971 to 23,597 in 2001, while the number of car-killed red deer increased from 27 to 443 over the same period. I analysed how the temporal variation in the annual number of car-killed red deer along the west coast of Norway varied with population density and climate. The increase in the number of car-killed red deer was mainly an effect of increasing population size (as evidenced from harvest records). The parameter estimate for the population size effect was 1.722 and 1.025, respectively, before and after adding the (non-significant) effect of ‘year‘ (as a continuous term). An increase in population size therefore led to an increase in the proportion of the number of car-killed red deer only when excluding the year effect which was likely due to an increase in traffic volume. Spring conditions, as measured by the March–May value of the North Atlantic Oscillation (NAO), correlated with the number of car-killed red deer, but winter, summer or autumn NAO did not. I argue that the consequences of an increasing number of car-deer collisions with increasing population density should be incorporated into future modelling of harvesting strategies if the aim is to maximise the economic outcome at a national scale.