Habitat Relationships of Wood Warblers (Parulidae) in Northern Central Minnesota

Abstract

To analyze the habitat relationships of 16 spp. of wood warblers (Parulidae) breeding in northern central Minnesota, 13 variables of the structure of the habitat were measured in 207 0.04-ha circular plots located in the territories of breeding males. Cluster analysis of the average habitats of the species identified 3 groups of species occupying shrub-forest edge (Dendroica magnolia, Mniotilta varia, Setophaga ruticilla, Vermivora ruficapilla, Wilsonia canadensis), mature forest (D. coronata, D. fusca, D. pinus, D. virens, Seiurus aurocapillus, Parula americana), and open fields with shrubs (D. pensylvanica, D. petechia, Geothlypis trichas, Oporornis philadelphia, V. chrysoptera). A reciprocal averaging ordination of 1st axis extends from forest vegetation to habitats with few trees and dense ground cover. A 2nd axis separates areas of coniferous forest from those of younger deciduous and mixed forest. A principal components analysis of 199 samples permitted the construction of ellipses that reflect the variability and overlap in the habitat of each species. The distribution of the species and the variation within the habitat of each are mainly attributable to affinities to biotic resources such as food, nest sites and certain elements of the structure of the vegetation. To infer that these relationships represent the results of interspecific interactions is not justified.