Cutting the carnage: wildlife usage of road culverts in north-eastern New South Wales

Abstract

Culverts have been used for a number of decades in Europe and the USA to reduce wildlife road-kills. In Australia, culverts have been employed by road authorities only relatively recently. This study used sand-strip surveys to investigate wildlife usage of nine purpose-built culverts along a 1.4-km section of the Pacific Highway at Brunswick Heads, north-east New South Wales. Surveys during two eight-day periods in spring and summer 2000 found 1202 traverses by wildlife through the culverts. Frequent culvert users were bandicoots (25% of traverses), rats (25%), wallabies (13%) and cane toads (14%). All culverts were used by these species, suggesting that at least several individuals of each species were involved. Infrequent users (each <2% of crossings) were possums, echidnas, lizards, birds and introduced carnivores. A koala was recorded crossing on two occasions. The long-nosed potoroo was observed in the surrounding habitat but was not confirmed traversing the culverts. Surveys for road-kills on this road section suggest that the exclusion fence bordering the highway prevented mammal road-kills and channeled mammals to the culverts. A single survey on a wet night found many frogs crossing the road surface and many were killed. This study confirms that culverts and exclusion fencing facilitate safe passage across a road for a range of wildlife species. This suggests that this form of management response to extensive road mortality of wildlife is appropriate and should be adopted more widely. However, this form of mitigation is not effective for frogs.