Migration, habitat utilization, and behavior of six shorebirds (Charadriformes) on Bon Portage Island, Nova Scotia
LE3 .A278 1984
Smith, Peter C.
Master of Science
A preliminary study of shorebirds (Charadriiformes) that stop to forage on Bon Portage Island, Shelburne County, N.S., was undertaken during the summers of 1982 and 1983. Research focused on the pattern of migration, habitat utilization, and behavior of six species. The shorebirds studied included three species in the family of shorebirds studied included three species in the family Scolopacidae: Semipalmated Sandpiper Calidris pusilla (L.), Least Sandpiper Calidris minutilla (Vieillot), and Short-billed Dowitcher Limnodromus griseus (Gmelin) and three in the Charadriidae family: Semipalmated Plover Charadrius semipalmatus Bonaparte, Black-bellied Plover Pluvialis squatarola (L.) and Ruddy Turnstone Arenaria interpres (L.) (for the purposes of this thesis turnstones are considered charadriids). These species were chosen to compare and contrast morphological as well as behavioral differences in foraging. Semipalmated Sandpipers were the most abundant species. Peaks in shorebird migration coincided with highs in daylight feeding period. In general, migration in 1983 was later than in 1982. Shorebirds foraged primarily on three intertidal sandy beaches with wrack beds and on an adjacent sandbar within a lagoon. The largest beach and sandbar were sampled and invertebrate prey items were identified. The kelp fly Coelopa frigida Fabricius was the most abundant prey itern in the wrack. Location of feeding birds with relation to tide was recorded. Shorebirds appeared to forage where selective prey were most available relative to tidal level. Birds of different species were collected after foraging in selected areas. Gut contents showed c. frigida to be the major prey item. An index of aggression was calculated for each species feeding in different areas. Ruddy Turnstones and Semipalmated Sandpipers were most aggressive while the larger Short-billed Dowitchers and Black-bellied Plovers were the least aggressive birds. Peck rates showed no consistent trend.
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