Engstrom, T.R. 1989. Bird counts in Minnesota habitats: a review. Final report submitted to the Minnesota Department of Natural Resources. 28+ pp.
The objectives of this study were to review the literature on Minnesota bird communities, identify habitats for which the bird communities are poorly documented, and to obtain estimates of bird species richness in the habitats of Minnesota by using the statistical technique, rarefaction. The Breeding Bird Census (BBC) is the largest source of standardized plot-based counts of birds conducted in North America. Estimated species richness for a sample of individuals standardized to 8.1 ha for 62 BBC plots in Minnesota. The number of species estimated for 8.1 ha ranges from 3.5 in open fen to 28.2 in elm-birch-ash forest. Within a single plot, the number of species varied considerably among years. The strengths and value of the BBC and the Winter Bird Population Study (WBPS) far outweigh the weaknesses. To date these databases represent the most extensive collection of information on the bird populations in specific habitats in Minnesota. Independent studies, including theses, dissertations, and published papers, are highly diverse. Comparing results among these studies would be difficult and risky. Expanding and improving the BBC and WBPS would be an inexpensive way to provide good data on the bird communities of Minnesota.