Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub


    Trade‐offs in resource selection by central‐place foragers are driven by the need to balance the benefits of selecting resources against the costs of travel from the central place. For group‐territorial central‐place foraging birds, trade‐offs in resource selection are likely to be complicated by a competitive advantage for larger groups at high group density that may limit accessibility of high‐quality distant resources to small groups. We used the group‐territorial, central‐place foraging Red‐cockaded Woodpecker Leuconotopicus borealis (RCW) as a case study to test predictions that increases in group density lead to differences in foraging distances and resource selection for groups of different sizes. We used GPS tracking and LiDAR‐derived habitat data to model effects of group size on foraging distances and selection for high‐quality pines (≥ 35.6 cm diameter at breast height (dbh)) and lower quality pines (25.4–35.6 cm dbh) by RCW groups across low (n = 14), moderate (n = 10) and high group density (n = 10) conditions. At low and moderate group density, all RCW groups selected distant high‐quality pines in addition to those near the central place because competition for resources was low. In contrast, at high group density, larger groups travelled further to select high‐quality pines, whereas smaller groups selected high‐quality pines only when they were close to the central place and, conversely, were more likely to select lower quality pines at greater distances from the central place. Selection for high‐quality pines only when close to the cavity tree cluster at high group density is important to long‐term fitness of small RCW groups because it allows them to maximize benefits from both territorial defence and selecting high‐quality resources while minimizing costs of competition. These relationships suggest that intraspecific competition at high group density entails substantive costs to smaller groups of territorial central‐place foragers by limiting accessibility of distant high‐quality foraging resources.

    Publication Notes

    • You may send email to to request a hard copy of this publication.
    • (Please specify exactly which publication you are requesting and your mailing address.)
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Garabedian, James E.; Moorman, Christopher E.; Peterson, M. Nils; Kilgo, John C. 2020. Effects of group size and group density on trade‐offs in resource selection by a group‐territorial central‐place foraging woodpecker. Ibis.2020 162, 477-491. 15 p.


    Google Scholar


    competition, density dependence, endangered species, forest structure, functional response, LiDAR, Red-cockaded Woodpecker, space use

    Related Search

    XML: View XML
Show More
Show Fewer
Jump to Top of Page