Effects of trail width on the densities of four species of breeding birds in chaparral

Abstract

We investigated densities of four common species, Wrentit (Chamaea fasciata), Spotted Towhee (Piplio erythrophthalmus), Bewick’s Wren (Thryomanes bewickii), and Orange-crowned Warbler (Vermivora celata) in relation to trail width in chaparral habitats of Mt. Tamalpais, Marin County, California. Point count sampling stations were assigned to one of three trail width groups—thin (≤2 m), medium (2.1-4 m), and wide (>4 m). We found a marginally significant (P < 0.1) negative effect of trail width on the density of Spotted Towhee when thin trails were compared to medium/wide trails. For the other three species our results suggest a trail width effect when thin trails were compared to medium/wide trails (P < 0.2), although additional study is needed to confirm or negate these tentative conclusions. Only one species, Orange-crowned Warbler, showed a positive relationship between density and trail width.

Parent Publication

• Bird Conservation Implementation and Integration in the Americas: Proceedings of the Third International Partners in Flight Conference. 2002 March 20-24; Asilomar, California, Volume 1 and 2

Citation

Holmes, Aaron L.; Geupel, Geoffrey R. 2005. Effects of trail width on the densities of four species of breeding birds in chaparral. In: Ralph, C. John; Rich, Terrell D., editors 2005. Bird Conservation Implementation and Integration in the Americas: Proceedings of the Third International Partners in Flight Conference. 2002 March 20-24; Asilomar, California, Volume 1 Gen. Tech. Rep. PSW-GTR-191. Albany, CA: U.S. Dept. of Agriculture, Forest Service, Pacific Southwest Research Station: p. 610-612