2000 Breeding Bird Survey Report: Apostle Islands National Lakeshore

Smith, Geoffrey; Van Stappen, Julie; Hoff, Michael

The Apostle Islands National Lakeshore breeding bird survey was established in 1990 to determine the status and trends of breeding birds in the Lakeshore and in response to the growing need to document abundance trends of Neotropical migrant birds in the United States. The significance of this project has continued to grow, such that the abundance trends of Neotropical migrant birds are now recognized by the Lake Superior Binational Forum as an indicator of overall ecosystem health within the Lake Superior basin. The 2000 breeding bird survey was conducted from 8 June to 29 June. Ten minute point counts were conducted at 106 points distributed along ten transects. Wind and rain hampered survey efforts but all transects were completed in 2000. The 2000 survey marks the sixth year that data collection has occurred at permanently marked points. When comparing results from 1995-2000, data from 1998 was not included because Oak, Devils, and Raspberry Island transects were not surveyed that year. Data collected from 1991 to 1994 were summarized in the 1997 breeding bird survey report (Gostomski and Van Stappen 1997) and are included in the 2000 report for multiyear comparison analysis. A total of 1013 birds comprising 77 species were observed in 2000. The mean number of birds per survey point was 10. The highest number of birds per point was found on Sand Island (15). The lowest number of birds per point was on Outer (7). The highest number of total birds was found on Sand and Stockton Islands (174). The later has the most points. Stockton Island (10, 054 a) supported the highest number of species (39), followed by Outer Island (10,000 a) and the Mainland (34) (2565 a). The lowest number species recorded was on Oak Island (18). Species diversity on islands/mainland ranged from 0.96 (Oak Island) to 1.40 (Mainland), with a mean diversity of 1.26. Species diversity for habitat ranged from 0.92 (beaver flowage) to 1.44 (pine forests) with a mean diversity of 1.15. By habitat, the highest number of birds per point was boreal and pine forest habitat (12), followed by conifer forest, old-growth northern hemlock forest, and shrubby sandscape habitat (10). The total number of birds was highest in pine forest habitat (185), followed by boreal forest (149) and northern hardwood-sugar maple (128). The number of species by habitat was highest in pine (43) and boreal forests (33). Simple linear regression analysis revealed a declining trend in total bird numbers from 1991-2000 (5-minute counts). There were also declining trends on transects on Devils and Raspberry Islands, the Mainland Unit, and the Presque Isle transect on Stockton Island. Declining species between 1991-2000 (5-minute counts) include black and white warbler, mourning warbler, Swainson’s thrush, veery, blue jay, and red-wing blackbird. Nashville warbler declined between 1995-2000 (10-minute counts). Northern parula and Philadelphia vireo showed an increasing trend between 1991-2000 (5-minute counts). The Lakeshore results were consistent with regional trends for mourning warbler and veery (declining trend). Nashville warbler regional trends were mixed. Blue jay declined in the Lakeshore but increased regionally. There was no significant regional trend for black and white warbler or red-wing blackbird. The veery is of special concern because it had declining trends at all levels, including the Lakeshore, Wisconsin, regionally, and nationally.