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Effects Of Field Size And Landscape Composition On Grassland Birds In South-Central Iowa, David Joseph Horn, Rolf R. Koford, Malinda L. Braland

Journal of the Iowa Academy of Science: JIAS

Many species of grassland birds have been shown to avoid smaller fields. The avoidance of smaller fields, however, has not been consistently reported; avoidance may occur in one study, but not in another. To examine one possible reason for these inconsistencies, we examined how landscape composition influenced the relations between occurrence or abundance and field size. The study took place during the 1998 breeding season on 44 Conservation Reserve Program (CRP) fields located in Adair, Ringgold, and Union counties. The relations between occurrence, abundance, and field size were not influenced by landscape composition for any species.

Grasshopper Sparrow, Ammodramus savannarum, …

Factors Influencing The Occurrence Of Birds That Use Feeders In Iowa, David Joseph Horn, Steve E. Fairbairn, Richard J. Hollis

Journal of the Iowa Academy of Science: JIAS

Since its inception in 1984, data from the annual Iowa "Winter Bird Feeder Survey" have provided valuable information about birds that use feeders in Iowa such as spatial and temporal population trends. Using data from the 1988 and 1994 Surveys, we examined how the occurrence of bird species that use feeders was influenced by geographic location, the habitat surrounding a house, and the types of seeds offered at a house. Of the 23 species examined, the occurrence of 8 species was influenced by latitude, 22 species were influenced by the habitat surrounding the house, and 22 species were influenced by …