Experimental Design Considerations for Establishing an Off-Road, Habitat-Specific Bird Monitoring Program Using Point Counts

Abstract

We established bird monitoring programs in two regions of Minnesota: the Chippewa National Forest and the Superior National Forest. The experimental design defined forest cover types as strata in which samples of forest stands were randomly selected. Subsamples (3 point counts) were placed in each stand to maximize field effort and to assess within-stand and between-stand variation for a variety of bird parameters. Data gathered in 1991 were used to evaluate several assumptions that were made in the experimental design and showed that variance of most bird parameters among strata were similar. This data indicated that a proportional stratified sample by forest cover type was reasonable. We also found that two subsamples per stand would be optimum when a variety of strata types and bird variables were considered. Analyses based on 120 stands in the Chippewa National Forest and 150 stands in the Superior National Forest indicated that a two-tailed t-test could detect a 25 percent change in bird numbers for common species. For most other species, we could detect less than a 50 percent annual change. Monitoring programs within regions should be habitat specific so that changes in bird numbers can be related to: (1) habitat changes that have occurred in the region; (2) natural fluctuations in bird numbers; or (3) other factors.

Parent Publication

• Monitoring bird populations by point counts

Citation

Hanowski, JoAnn M.; Niemi, Gerald J. 1995. Experimental Design Considerations for Establishing an Off-Road, Habitat-Specific Bird Monitoring Program Using Point Counts. In: Ralph, C. John; Sauer, John R.; Droege, Sam, technical editors. 1995. Monitoring bird populations by point counts. Gen. Tech. Rep. PSW-GTR-149. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: p. 145-150