Roadkill is the main cause of mortality for the endangered subspecies of American badger found in British Columbia (Taxidea taxus jeffersonii). Badgers sometimes use culverts to pass under roads, so more culverts might be associated with less roadkill risk. Risk may also be associated with the presence of Jersey barriers, which potentially trap badgers on roadways. We compared 39 1-km highway segments where roadkills occurred to 39 random segments, to see if they differed in the number of culverts and bridges useable by badgers or in the presence or distance covered by Jersey barriers. About 18% of structures in random segments and 40% in roadkill segments were impassable to badgers. Compared to random segments, roadkill-associated segments were less likely to have at least two structures/km passable by badgers (26% of roadkill segments vs. 59% of random segments; χ2 = 8.877, P = 0.003). This supports the notion that badger roadkill risk is lower where an adequate supply of culverts or bridges exists. The presence or amount of Jersey barrier was not related to roadkill risk. This may reflect a lack of effect, or may relate to a difficulty in detecting trends given the few Jersey barriers in our study area and their apparently disproportionate use where badger habitat is poor and where options exist to avoid barriers. Increasing the opportunities for badgers to pass under highways through culverts should reduce mortality and aid recovery. We recommend repairing or retrofitting existing structures, making entrances more visible, installing drift fencing where appropriate, installing more culverts, and investigating culvert or landscape characteristics associated with the use of culverts by badgers.
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1 April 2009
Badger Roadkill Risk in Relation to the Presence of Culverts and Jersey Barriers
Trevor A. Kinley,
Nancy J. Newhouse
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