Use of highway undercrossings by wildlife in southern California

  • Published source details Ng S.J., Dole J.W., Sauvajot R.M., Riley S.P.D. & Valone T.J. (2004) Use of highway undercrossings by wildlife in southern California. Biological Conservation, 115, 499-507.


This study is summarised as evidence for the following.

Action Category

Install tunnels/culverts/underpass under roads

Action Link
Terrestrial Mammal Conservation
  1. Install tunnels/culverts/underpass under roads

    A replicated study in 1999–2000 along three major highways in California, USA (Ng et al. 2004) found that tunnels, culverts and underpasses were used by mammals. Fourteen of the 15 passages were used by racoons Procyon lotor (making 207 crossings), eight by opossums Didelphis virginianus (24 crossings), seven by coyotes Canis latrans (59 crossings), seven by bobcats Lynx rufus (36 crossings), five by striped skunks Mephitis mephitis (23 crossings), three by mule deer Odocoileus hemionus (26 crossings), one by spotted skunks Spilogale putorius (five crossings) and one by a mountain lion Puma concolor (one crossing). Crossing numbers include both verified and probable crossings. Rodents and cottontail rabbits Sylvilagus auduboni were also recorded. Six square livestock tunnels, five drainage culverts and four underpasses (surface roads or wide stream crossings) were studied. Passages were 44–218 m long and 2–238 m2 in cross-section. Camera traps were used in four passages and powder stations to detect animal footprints in 12 passages. One passage was monitored using both methods. Monitoring occurred over four consecutive days/month between July 1999 and June 2000.

    (Summarised by: Lauren Vorhees & Kayla Seltzer)

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