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Egg Removal By Brown-Headed Cowbirds: A Field Test Of The Host Incubation Efficiency Hypothesis, Douglas R. Wood
Egg Removal By Brown-Headed Cowbirds: A Field Test Of The Host Incubation Efficiency Hypothesis, Douglas R. Wood
Masters Theses
Obligate brood parasites, like the Brown-headed Cowbird (Molothrus ater), lay their eggs in the nests of host species, usually to the detriment of the host's reproductive effort. In addition, Brown-headed Cowbirds often remove one or more host eggs near the time of parasitism. Although several hypotheses exist, the adaptive significance of egg removal has not been clearly established. Peer and Bollinger (in press) proposed the host incubation efficiency hypothesis which states that the number and size of host eggs influences the incubation efficiency of a parasitic egg. Thus, host egg removal by cowbirds should increase the parasitic egg's …
Reproductive Success Of Grassland Birds At East-Central Illinois Airports, Eric L. Kershner
Reproductive Success Of Grassland Birds At East-Central Illinois Airports, Eric L. Kershner
Masters Theses
We determined the densities and reproductive success of birds on airport grasslands in east-central Illinois. Seven airports were sampled between 10 April and 15 August 1994 in Clark, Coles, Crawford, Douglas, Edgar, Macon and Richland counties. Nineteen species were detected on the airport grasslands and 147 nests were found representing six different species. Eastern meadowlarks (Sturnella magna) were the most abundant nesting species found; 105 out of the 147 nests (71%). Other nesting species included: grasshopper sparrow (Ammodramus savannarum), savannah sparrow (Passerculus sandwichensis), red-winged blackbird (Agelaius phoeniceus), song sparrow (Melospiza melodia) and horned lark (Eremophilia alpestris). Overall nest success was …