Changes in Breeding Bird Populations in North Dakota: 1967 to 1992-93.

Breeding bird populations in North Dakota were compared using surveys conducted
in 1967 and 1992-93. In decreasing order, the five most frequently occurring
species were Horned Lark (Eremophia alpestris), Brown-headed Cowbird (Molothrus
ater), Western Meadowlark (Sturnella neglecta), Red-winged Blackbird (Agelaius
phoeniceus), and Eastern Kingbird (Tyrannus tyrannus). The five most abundant
species - Horned Lark, Chestnut-collared Longspur (Calcarius ornatus),
Red-winged Blackbird, Western Meadowlark, and Brown-headed Cowbird - accounted
for 31-41% of the estimated statewide breeding bird population in the three
years. Although species composition remained relatively similar among years,
between-year patterns in abundance and frequency varied considerably among
species. Data from this survey and the North American Breeding Bird Survey
indicated that species exhibiting significant declines were primarily
grassland- and wetland-breeding birds, whereas species exhibiting significant
increases primarily were those associated with human structures and woody
vegetation. Population declines and increases for species with similar habitat
associations paralleled breeding habitat changes, providing evidence that
factors on the breeding grounds are having a detectable effect on breeding
birds in the northern Great Plains.