Breeding Birds of the Cornish Hardwood Management Area: Aitkin County, Minnesota 1998-1999

Abstract

Breeding bird surveys were conducted for the second consecutive year in the Cornish Hardwood management area (CHMA), located in northeast Aitkin County. The objectives of this project are to: 1) establish a long-term breeding bird monitoring program in the CHMA to detect annual changes in species abundances, 2) determine whether bird community composition and species abundances are affected by uneven-aged management, and 3) compare the bird community in the CHMA with other northern hardwood stands in northern Minnesota. This report provides a summary of bird surveys completed in June of 1999 and also compares 1998 and 1999 survey results. Please refer to the 1998 report for more detail on methods and rationale for this study. Twenty-six individual stands that were greater than 40 acres were selected for monitoring. Eight stands were harvested within the past 10 years (managed), eight stands are in the management area, but have not been recently managed (unmanaged), and ten sites were located in Savannah Portage State Park. One breeding bird survey was conducted at each point with an unlimited radius 10 minute count point count in Junes of 1998 and 1999. A total of 25 bird species were observed in 26 stands (52 points) in 1998 and 32 species were counted in 1999. Over both years, a total of 37 species have been observed in this area. On average, we observed about 22 individuals and 7 to 8 species in each stand (total of two point counts) in 1998 and a slightly higher number, about 25 individuals and 8 species in 1999. Results of a two-way analysis of variance for the bird community variables indicated that more (P < 0.001) total individuals were observed in 1999 than in 1998. In addition, we found a significant difference in number of species observed in stands with different management history. Here, unmanaged stands had fewer species (P < 0.01) than the managed or reference stands. Not one of the 8 species tested with two-way analysis of variance indicated a significant difference (P < 0.05) in abundance among management types or year. We found a significant interaction for year and treatment for the Scarlet Tanager. This test result indicated that the species abundance pattern on unmanaged sites was not consistent between 1998 and 1999. For example, more Scarlet Tanagers were observed on unmanaged sites in 1998 than in the other two management groups, but in 1999, this management type had the fewest number of individuals of this species. A cluster analysis with bird species showed that bird community composition was not different among management types or between years. Occurrence of uncommon species on individual sites was most likely the reason why some sites differed in their relative cluster position (or composition of cluster) between the two years. A species that was absent in northern hardwood stands in this region in 1998 but present in 1999 was the Black-throated Blue Warbler. This species is rarely found in northern hardwoods in north central Minnesota but occurs in selected northern hardwood stands in northeast Minnesota, primarily in the Lake Superior highlands. A recently completed study on the Black-throated Blue Warbler in northeast Minnesota applied in managing in 1999 will provide quantitative habitat information for this species that could be the CHMA for this hardwood dependent species.