Ornithology Commons^™

Wintering Distribution Changes In Mallards And Black Ducks, Paul A. Johnsgard

Papers in Ornithology

Through the use of data compiled by the Audubon Society's annual Christmas Counts, an attempt has been made to trace the distributional changes of wintering Mallards and Black Ducks in the eastern states from 1900 to the present. During this period the Black Duck has increased relative to the Mallard in few if any states (the Great Lakes region), whereas the Mallard has increased nearly everywhere else (except in the extreme northeast), particularly in the southern coastal states. Deforestation and changes in land use are sug- gested as probable reasons for this trend, which is not likely to be reversed.

Evolutionary Relationships Among The North American Mallards, Paul A. Johnsgard

Papers in Ornithology

A comparative morphological, behavioral, and electrophoretic study was undertaken on six populations of North American mallards that are currently considered by the A.O.U. Check-list to comprise four species and two additional subspecies. These include Anas p. platyrhynchos, A. d. diaxi, A. d. novimexicana, A. f. fulvigula, A. f. maculosa, and A. rubripes. These forms are essentially allopatric in their breeding distributions, with the major exception of A. p. platyrhynchos and A. rubripes, which overlap throughout a several-hundred-mile zone in east-central United States.

Geographic ranges and population sizes are estimated, and evidence is presented to indicate that the …

Trematodes Recovered From Passerine Birds Collected In Chickasaw County, Iowa, (With Notes On Other Avian Helminths), Charles J. Ellis

Dissertations and Theses @ UNI

The present study is a survey of the trematodes found in passerine birds collected in the Goodale Conservation Area of Chickasaw County, Iowa, from October 1959 through August 1960. Non-trematodic infections are reported also.