Data from: Demographic costs associated with differences in habitat space occupancy

Delimiting the habitat characteristics describing the environmental
conditions required by a species has become a critical tool for predicting
organismal responses to environmental change. Grinnell emphasized the
effects of environmental factors on the ability of a population to
maintain a positive growth rate, yet few studies have included demographic
or reproductive data in analyses of the Grinnellian niche. Identifying
differences in habitat exploitation patterns in response to structural
variation in the environment presents an incomplete description of the
ability of species to adapt to changing habitats if demographic traits are
not included. We estimated the vegetation characteristics used by
individuals within a population of hooded warblers (Setophaga citrina)
across a spatial transect that includes three structurally different
forest habitats. We predicted individuals should select similar structural
characteristics within each habitat and have similar reproductive success
across sample sites. In the two years post burn, adults were present but
no young fledged indicating the habitat requirements necessary for
reproduction were absent in this habitat. We found significant differences
in habitat space occupied by individuals in unaltered and harvested
habitats. Nesting habitats used by female warblers differed from available
habitat. Fledging success was lower in the harvested habitat 10 to 12
years post-harvest. In the harvested habitat, fledging success was greater
on mesic slopes but decreased along a habitat gradient to xeric ridgetops,
suggesting compensation in habitat use does not ameliorate fitness costs.
In contrast, there was no difference in the number of fledged young along
this gradient in the unaltered habitat. Based solely on occupancy data,
traditional ecological niche models would incorrectly conclude the
environmental characteristics found across the three forested habitats are
included in the Grinnellian niche of the hooded warbler. However,
examination of demographic and environmental data simultaneously allows
differentiation between occupied habitat space and niche space.