Document: DAV-3-53-3

Vertical organization of the small bird community in an old-growth Douglas-fir/western hemlock forest.

SHAW, D.C.* ^1,2, E.FREEMAN ^1,2 and C.FLICK ³

Wind River Canopy Crane Research Facility ¹
University of Washington, WA USA ²
Gifford Pinchot National Forest ³

Abstract:
The vertical organization of the small bird community (songbirds, small woodpeckers, nighthawks, and swifts) in a 500 year old Douglas-fir/western hemlock forest was quantified by the use of a construction crane (Wind River Canopy Crane Research Facility). We used a gondola suspended from the crane to do a weekly series of vertically stratified point counts in the lower (0-20 m), mid (20-40 m) and upper (40-60+ m) canopy. Data is from March 21, 1996 to March 21, 1999, and included 121 survey days (average 40.3/yr). Chi Square Goodness of Fit test was used to determine if individual bird species were evenly distributed through the canopy (do numbers differ from random?). Analysis of Deviance using a poisson error structure and a log link, was used to determine the effect of season, canopy level, and their interaction for six abundant resident songbirds. The most birds, species, and guilds were detected in the upper canopy, whereas the Shannon-Weiner diversity index was equal for the low and upper canopy and slightly less for the mid canopy. Fifteen species, of the twenty most common, were detected significantly more often in one zone of the canopy, while five species were not. Timber foliage insectivores, air insectivores, and timber seed eaters all stratify the canopy, as do most low understory herbivore-insectivores. Bark insectivores and omnivore-scavengers tend not to stratify the canopy. The Chestnut-backed Chickadee (p = 0.0000), Brown Creeper (p = 0.0002), Red Crossbill (p = 0.0049), and Gray Jay (p = 0.0360) all shift canopy levels with the seasons, whereas the Golden-crowned Kinglet (p = 0.0660) and Winter Wren (p = 0.7997) do not. The small bird community of this old-growth forest is vertically organized.

Keywords: small forest birds, vertical stratification

This abstract is being presented at: 8:30 AM in session:
Oral Session #3: Avian Ecology.