Use of Tree Species by Forest Birds during Winter and Summer

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Abstract
We recorded the foraging behavior of bird species during winter and summer in a mixed conifer forest of the western Sierra Nevada [USA]. All bird species increased their relative use of incense cedar (Calocedrus decurrens) in winter compared to summer. We noted no obvious difference in the vigor (health) of trees used by birds between seasons. Most species revealed a general trend towards increased use of the bark of incense cedar in winter relative to summer. It appears that birds are able to obtain food from under the loose, flaky bark of incense cedar more easily than from under the more firm, compact bark of other timber species in winter. The overwinter survival of birds may be lowered by reduction in the stocking level of small (< 30 cm dbh) incense cedar.