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Weather and bird populations in true fir forests of the Sierra Nevada, California

Hejl, S. J. and Verner, J. and Balda, Russell P. (1988) Weather and bird populations in true fir forests of the Sierra Nevada, California. Condor, 90 (3). pp. 561-574. ISSN 1938-5129


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Publisher’s or external URL: http://dx.doi.org/10.2307/1368344


Bird communities were monitored in fir (Abies spp.) forests at 51 sites in the western Sierra Nevada during the breeding seasons of 1983, 1984 and 1985. The El Niño winter of 1982-83 had the greatest snowfall on record. The summers of 1984 and 1985 followed winters with moderate snowfalls. Bird species richness and average total count increased linearly from 1983 to 1985. The relative abundances of 12 common species increased from 1983 to 1985. Abundances of two common species did not differ among years. Twenty-eight uncommon species increased and four decreased in numbers from 1983 to 1985. Bird response patterns differed between lower-altitude white fir (A. concolor) forests and upper-altitude red fir (A. magnifica) forests. Bird numbers were similar in both habitats in 1983 but greater in white fir then in red fir in 1984 and 1985. Abundances of the common species increased in both habitats in both years, but abundances of uncommon species did not increase substantially in red fir until 1985. It was suggested that bird numbers were depressed in 1983, although not atypically so for fir forests, and that white fir and low-altitude forests might harbour 'source' populations for red fir 'sink' populations during periods of resource stress.

Item Type: Article
Publisher’s Statement: © 1988 The Cooper Ornithological Society.
ID number or DOI: 10.2307/1368344
Keywords: Abies; Abies concolor; ABIES magnifica; AMERICA; Animals; APEC countries; Biological Resources (General) (PP700); Birds; California; Chordata; Colorado fir; CONIFERS; Developed Countries; Ecology; eukaryotes; Forests and Forest Trees (Biology and Ecology) (KK100); gymnosperms; North America; OECD Countries; Pacific States of USA; Pinaceae; Pinopsida; PLANTS; Spermatophyta; United States of America; USA; Vertebrates; Western States of USA
Subjects: Q Science > QL Zoology
NAU Depositing Author Academic Status: Faculty/Staff
Department/Unit: College of Engineering, Forestry, and Natural Science > Biological Sciences
Date Deposited: 30 Sep 2015 22:17
URI: http://openknowledge.nau.edu/id/eprint/517

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