Bird counts, bird census, bird populations, Iowa birds, habitat changes
A comparison of Breeding Bird Survey (BBS) data in Iowa between 1968-1970 and 1978-1980 suggests that 19 species have increased in numbers and that 18 have declined over that period. Most species showing increases are associated with agricultural and grassland habitats. Most species showing decreases are associated with agricultural and edge-oldfield habitats. A variety of factors is probably responsible for these declines. BBS results are fairly consistent with the National Audubon Society's Blue List - birds thought to be declining - but show little correlation with that group's list of species of special concern. The BBS detected at least 68% of the birds known to breed in Iowa, although not all of those were detected each year. About the same number of species were reported from each of five regions in the years considered, although the same species were not seen in all areas. Still, 73 species reported in all five regions dominate the state's avifauna. Some biases related to the species' detectability and observer competence are evident in the data. Overall, BBS data do seem to be meeting their goal of providing quantitative information useful in detecting long-term changes in bird populations.
Proceedings of the Iowa Academy of Science
©1985 Iowa Academy of Science, Inc.
Zaletel, Linda R. F. and Dinsmore, James J.
"Breeding Bird Populations in Iowa, 1968-1980,"
Proceedings of the Iowa Academy of Science, 92(3), 85-94.
Available at: https://scholarworks.uni.edu/pias/vol92/iss3/3