Document: SUS-3-76-14

Linking avian communities, riparian vegetation, and geomorphology along a prairie river, USA.

SKAGEN, S.K.* ¹, M.L.SCOTT ¹ and M.F.MERIGLIANO ²

U.S. Geological Survey, Fort Collins, CO 80525, U.S.A. ¹
University of Montana, Missoula, MT, U.S.A. ²

Abstract:
The structure of riparian bird communities depends on various habitat and landscape characteristics. Two important processes that influence riparian vegetation in the American west are plant establishment and succession on new stream deposits, and livestock herbivory. We examined how bird species composition and abundance varied along 172 km of the upper Missouri River, a large, flow-regulated, geomorphically-constrained stream in central Montana. We sampled breeding bird abundance and vegetation structure in 34 sample sites that included three habitat types. We related geomorphic activity since 1953 and grazing history to the existing riparian vegetation, thus connecting these processes to bird community structure via vegetation structure and landscape character of habitat. We used several univariate and multivariate analysis to define and test the above relations. Vegetation structure was most strongly related to bird abundance, while landscape character was poorly related. Many bird species representing several foraging guilds were strongly associated with and occurred in greater densities in forest stands of complex structure, whereas only a few bird species were denser in forest stands with no understory. The linkage between riverine processes, riparian vegetation, and avian communities holds strong implications for long-term avian conservation efforts.

Keywords: flood plain dynamics, vegetation structure, avian communities, conservation

This abstract is being presented at: 2:30 PM in session:
Oral Session #14: Disturbance Effects on Bird Populations.