Pacific Southwest

Title: Bird foraging on incense-cedar and incense-cedar scale during winter in California

Author: Morrison, Michael L.; Dahlsten, Donald L.; Tait, Susan M.; Heald, Robert C.; Milne, Kathleen A.; Rowney, David L.

Date: 1989

Source: Res. Pap. PSW-RP-195. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 16 p

Station ID: RP-PSW-195

Description: Seasonal differences in use of food and habitat have been shown for numerous bird species. Especially during winter, when insect food is often at its lowest availability, birds may be unable to secure enough food for survival. In earlier work in the mixed-conifer zone of the western Sierra Nevada (Blodgett Forest, El Dorado County), observers found that many birds significantly increased their relative use of incense-cedar (Calocedrus decurrens [Torr.] Florin.) for foraging in winter as compared to summer. Preliminary examination of cedar showed the presence of one predominant arthropod species: the incense-cedar scale (Xylococculus rnacrocarpae Coleman). Scales were abundant under the loose, flaky bark of small (<20 cm diameter breast height 1d.b.h.l) cedar, and on limbs of larger cedar. Even bird species usually considered foliage-gleaners-for example, chickadees (Parus) and kinglets (Regulus) flaked and pecked the thin cedar bark. It was concluded from these observations that incense-cedar could be an important foraging substrate for birds during winter. But, current forest management practices often result in stands without a substantial component of small cedar. Thus, a conflict may exist between preferred forest practices and overwinter survival of some birds.

Keywords: Avifauna, bird density, bird foraging behavior, bird habitat use, calocedrus decurrens, incense-cedar, scale insect, Xylococculus macrocarpae, Sierra Nevada, California

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Citation

Morrison, Michael L.; Dahlsten, Donald L.; Tait, Susan M.; Heald, Robert C.; Milne, Kathleen A.; Rowney, David L.   1989.  Bird foraging on incense-cedar and incense-cedar scale during winter in California.   Res. Pap. PSW-RP-195. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 16 p.