Bird species-habitat relationships in managed northern hardwoods on the Ottawa National Forest /

by Brashear, Katherine Elaine.

Silvicultural treatments alter the composition and structure of forests for the purpose of producing timber and other forest products. With growing concerns for bird populations in forested habitats, the need to merge timber harvest goals with promoting bird biodiversity increasingly has become an important component of resource management for many National Forests. I investigated the relationship between three commonly applied silvicultural treatments (clear cut, selection cut, and shelterwood cut) and bird community composition in northern hardwood stands of the Ottawa National Forest, located in Upper Michigan, USA. My objective was to determine if differences in habitat structure were related to differences in bird community composition among silvicultural treatments. Multivariate analyses revealed that silvicultural treatment significantly was related to overall variation in habitat features among northern hardwood stands. Of nine vegetation features sampled, basal area, vertical structure, and diameter at breast height varied among treatment types. Five of nine habitat variables explained 87% of the variation in stand habitat structure among silvicultural treatments. These analyses also identified specific habitat features unique to individual silvicultural treatments. Seven of the 37 bird species detected 2004 and 2005 differed significantly among treatment type. The canonical correspondence output identified specific linkages between bird species presence and habitat variables as they related to silvicultural treatments. These findings will help resource managers in the Great Lakes northern hardwood forest region maintain habitat for viable bird populations by using a combination of silvicultural treatments. Implementing a mosaic of silvicultural treatments within the Ottawa National Forest should provide for regional bird biodiversity goals to be met. 1 The black-throated blue warbler, a lower shrub-layer nesting bird, has been identified as an area-sensitive species within the Ottawa National Forest, Michigan. The black-throated blue warbler is thus often used as an indicator species for quality, unfragmented mature interior forest. My objective was to determine if black-throated blue warblers selected their nesting territories for particular attributes of northern hardwood forests in the Ottawa National Forest. Territorial calls of black-throated blue warblers and habitat characteristics were noted during June 1-July 15 2004 and 2005 at 90 randomly generated point count locations. Discriminant function analyses revealed that sapling height and canopy height were important predictors of black-throated blue warbler occurrences in both years. Additionally, basal area and percent vertical cover 0-2.5 m were important habitat metrics in 2004 and 2005, respectively. Four black-throated blue warbler nests found in 2005 also confirmed the importance of conifer regeneration as nesting substrate in sugar maple-dominated forests. Conservation of this and other Neotropical bird species requires an understanding of regional habitat requirements necessary for population maintenance. 2 28 June 2006 Katherine Elaine Brashear 11689 S. Paynesville Rd. Trout Creek, MI 49967 906-852-3288 E-mail: kbras782@uwsp.edu