Demographic Costs Associated with Differences in Habitat Space Occupancy

PLoS One. 2016 Nov 16;11(11):e0165472. doi: 10.1371/journal.pone.0165472. eCollection 2016.

Abstract

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.

MeSH terms

  • Animals
  • Demography
  • Ecosystem*
  • Female
  • Male
  • Nesting Behavior
  • Reproduction / physiology
  • Songbirds / physiology*
  • Territoriality

Grants and funding

This work was funded by an Ohio Center for Ecology and Evolutionary Studies Research Fellowship, the Ohio Avian Project Initiative, the Midwest Birding Symposium Conservation Fund, Ohio University Graduate Student Senate Original Work Grants, the National Fire and Fire Surrogate Project and the Scioto Valley Bird and Nature Club.