Date of Award

5-1-1976

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Abstract

Rot&ntiaJ p*ey Ite-ns ol spotted sandpipers (Actms macularia L.) were sampled during the summer ol 1974 on Little Pelican Island , Leech Lake# Cass County* Minnesota. Most abundant terrestrial food items were Dipitera of the families Chironomidae and Sciaridae. Most abundant aquatic organism# were cladocera, copepods, and amphipods of the class Eucrustaeaa. Three large hatches of insects occurred. The first, during the last week of May, was predominantly midges (Chironomidae). The second and the largest occurred during the last week of June and the first week of July. Mayflies (Heptageniidae and Ephemeridae) were most abundant and comprised the majority of biomass during that period. Two or three midge species ware also abundant. Caddisflies (Trichoptera) composed the third hatch in the last week of July. Distributions of aquatic and terrestrial potential prey items were wind dependent. Wind velocities over 10 mph greatly reduced availability of potential prey items in exposed areas. Wind direction and vegetational characteristics determined trap success of each area—the interaction of which contributed to highly variable accumulations of potential prey within sheltered areas. Birds congregated in areas or highest toed densities and appeared opportunistic in feeding behavior, Nest initiation dates closely followed the first hatch— 12 of l-l females initiated nests within six days of the hatch. Projected hatch data* indteaUKt that chicks oi initial n+sts «*ouJa havo ipfawai lust prior to the second maior hatch of the season.

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