Effects of an Increasing Lesser Snow Goose Population on Shorebird Foraging Ecology at La Perouse Bay, Manitoba

In response to growing concerns over the potential consequences of degradation caused by an increasing population of lesser snow geese, this study was initiated in 1997 to determine the effects of degradation on shorebird foraging ecology at La Perouse Bay. Sampling was conducted from June 1 - August 10, 1997 and June 4 - August 8, 1998. For temporal analysis each annual collection period was partitioned into four seasons - spring, early-summer, late-summer and fall. For spatial comparisons all data were collected from two habitats - moderately degraded and severely degraded. Habitat classification was based on vegetation and substrate characteristics. Three 50 x 50 m plots were established in each habitat. One plot in each habitat was evaluated in 1997 while an additional two plots were evaluated in 1998 (1997 plots were not repeated in 1998). Modified point counts were used to determine shorebird relative abundance, species richness and species composition. Shorebird diet information was obtained using both lethal and non-lethal methods. Coring and pantraps were used to determine relative abundance of primary shorebird prey. Shorebird species richness was greater in moderate habitat (15 species) than in severe (11 species). Shorebird species composition varied between habitats, with seven species found in moderate that were not in severe and three observed in severe but not in moderate. Sufficient data were collected on dunlin (Calidris a/pina), least sandpiper (C minutilla), pectoral sandpiper (C melantos), semipalmated plover (Charadrius semipalmatus). semipalmated sandpiper (Calidris pusilla), short-billed dowitcher (Limnodromus griseus) and white-rumped sandpiper (Calidris fuscicoli/is). Log-linear modeling determined that distribution of these shorebirds between habitats was dependent on species and season. Dunlin, least sandpiper, semipalmated sandpiper and short-billed dowitcher were more abundant in moderate habitat, while pectoral sandpiper and semipalmated plover foraged more in severe habitat. White-rumped sandpiper showed an even distribution between the habitats. Large (>5 mm) immature Diptera, small seeds, small immature Diptera, small adult Diptera, and small Gastropoda were the most frequently consumed prey among the shorebirds. Distributions of prey varied temporally and spatially. Shorebirds selectively foraged on large immature Diptera, and the distribution of this prey dictated the distribution of shorebirds. Effects of degradation caused by lesser snow geese on shorebirds is dependant on the shorebird species in question. To fully understand the consequences of the degradation on shorebird and invertebrate ecology at La Perouse Bay, further research is warranted.

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Thesis - University Access Only

Discipline thesis:degree_discipline

Wildlife and Fisheries Science

Year

1999

Author dc:creator

• Vacek, Curtis M.

Contributors dc:contributor

• Lester D. Flake

• Natural Resources and Conservation

Statement dc:rights

• Copyright © 1999 Curtis M. Vacek. All rights reserved.

Language dc:language

en

Repository record dc:identifier

https://openprairie.sdstate.edu/etd/585

OAI identifier oai:identifier

oai:openprairie.sdstate.edu:etd-1585