The effect of road kills on amphibian populations

The diurnal movement patterns of Triturus vulgaris, Triturus cristatus, Pelobates fuscus, Bufo bufo, Rana temporaria, and Rana arvalis were investigated during five breeding seasons (1994-1998). Two main questions were addressed: (1) What is the probability of an individual amphibian getting killed when crossing the road? and (2) What fraction of the amphibian populations gets killed by traffic? The rate of movement of 203 adult amphibians was recorded. Information on traffic loads was provided, and mortality risk was calculated depending on traffic loads and movement rate. The probability of getting killed ranged from 0.34 to 0.61 when crossing a road with a traffic load of 3207 vehicles/day, and from 0.89 to 0.98 when crossing a motorway. The number of amphibians killed on the road was estimated by systematic counts. Population sizes were estimated for all ponds within 250 m of the relevant highway stretch. Results indicate that about 10% of, the adult population of P. fuscus and brown frogs (R. temporaria and R. arvalis) were killed annually by traffic at this site. (C) 2001 Elsevier Science Ltd. All rights reserved.