Evol Ecol Res 5: 913-932 (2003)     Full PDF if your library subscribes.

Null models of North American prairie duck communities: local habitat conditions and temporal scale influence community patterns

Erik E. Osnas* and C. Davison Ankney

Ecology and Evolution Group, Department of Zoology, University of Western Ontario, London, Ontario N6A 5B7, Canada

Address all correspondence to Erik E. Osnas, Department of Biology, Indiana University, 1001 E. Third Street, Bloomington, IN 47405, USA.
e-mail: eosnas@bio.indiana.edu


We developed null models that incorporate abundance of individuals at local sites to analyse community patterns of two North American duck guilds, dabbling and diving ducks. We compared patterns of species co-existence and morphological dispersion over two temporal scales, the entire breeding season and at weekly intervals. We found that patterns of co-existence depended on temporal scale and guild and that morphological dispersion depended on guild, temporal scale, character and local habitat features. Co-existence was non-random at all scales for both guilds but departures from the null model depended on scale for some individual species pairs. Generally, the most common species were negatively associated and less common species were positively associated. Dabbling ducks were not different from random communities for lamellar density at any scale or for body length at the seasonal scale, but were under-dispersed at the weekly scale. Diving ducks were over-dispersed in morphology at the breeding season scale but under-dispersed at the weekly scale. Patterns of morphology depended on local habitat characteristics because dabbling duck body length was only over-dispersed on the largest, most permanent, wetlands. Taken together, these results reveal that density compensation, temporal scale and local habitat characteristics influence patterns of co-existence in these wetland bird communities.

Keywords: community structure, null model, randomization test, species co-existence, waterfowl.

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