Habitat use of two songbird species: Response to forest management

Background/Question/Methods Birds rely on resources available within their territory during the breeding season.  Various forest management schemes alter the habitat and may result in birds altering territory size and location to adequately access resources and successfully fledge young. To evaluate how two types of disturbance affect the territory size and placement of  two species of breeding birds, we evaluated the habitat use of hooded warblers (Wilsonia citrina) and worm-eating warblers (Helmitheros vermivorus) in six treated mixed oak-pine stands in the William B. Bankhead National Forest in north-central Alabama.  The study design is randomized complete block with a factorial arrangement of three thinning levels (no thin, 11 m² ha^-1 residual basal area [BA], and 17 m² ha^-1 residual BA) and two burn treatments (burn and no burn).  Data was collected on three replicates.  Use of treated and adjacent areas and territory size was determined via territory mapping using radio telemetry and burst sampling methods.  Bird activity was recorded to evaluate potential differences in habitat preference during different activities.  All nests that were found were monitored and nest success was determined for each plot.  We used habitat variables collected within and outside territories to determine habitat preferences. 

Results/Conclusions

Our results suggest that birds on the treatment plots relied on areas left untreated in the stand or uncut areas adjacent to cut stands. Home ranges of both species were relatively large.  Habitat within home range had a greater slope, canopy cover, number of trees, basal area, and tree species richness than unused areas. Average home range located within the treated area was 45.2 percent for hooded warblers and 40.2 percent for worm-eating warblers.  The habitat the birds are choosing most likely has greater food resources than the treated areas. Increased vegetation is positively correlated with food availability and many arthropods are positively associated with interior forest, away from edges.