Foraging ecology of the California gnatcatcher deduced from fecal samples |
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| Authors: | Jutta C Burger Michael A Patten John T Rotenberry Richard A Redak |
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| Institution: | (1) Department of Entomology, University of California, Riverside, CA 92521, USA e-mail: jburger@citrus.ucr.edu, Fax: +1-909-7874733, US;(2) Department of Biology, University of California, Riverside, CA 92521, USA, US;(3) Center for Conservation Biology, University of California, Riverside, CA 92521, USA, US |
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| Abstract: | The California gnatcatcher is a threatened species essentially restricted to coastal sage scrub habitat in southern California.
Its distribution and population dynamics have been studied intensely, but little is known about its diet. We identified arthropod
fragments in 33 fecal samples of the California gnatcatcher to gain insight into its foraging ecology and diet. Fecal samples
were collected from adult males, adult females, fledglings, and nestlings. Leaf- and planthoppers (Homoptera) and spiders
(Araneae) predominated numerically in samples. Spider prey was most diverse, with eight families represented. True bugs (Hemiptera)
and wasps, bees, and ants (Hymenoptera) were only minor components of the gnatcatcher diet. Gnatcatcher adults selected prey
to feed their young that was larger than expected given the distribution of arthropod size available in their environment,
and chicks were provisioned with larger prey items and significantly more grasshoppers and crickets (Orthoptera) and spiders
than adults consumed themselves. Both adults and young consumed more sessile than active prey. Further studies are needed
to determine whether arthropods sampled in coastal sage scrub that are common in fecal samples are good indicators of California
gnatcatcher habitat.
Received: 30 December 1998 / Accepted: 28 April 1999 |
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| Keywords: | California gnatcatcher Coastal sage scrub Fecal analysis Foraging ecology Polioptila californica |
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