Landscape context and selection for forest edge by breeding Brown-headed Cowbirds
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We evaluated support for four alternate hypotheses explaining the distribution of breeding Brown-headed Cowbirds (Molothrus ater) in forests at varying distances from the forest edge in three Midwestern USA landscapes with varying amounts of forest fragmentation (core forest area ranged from 5 to 70%). We focused on breeding cowbirds’ use of forest because of the risk of nest parasitism to forest-dwelling hosts and to identify factors affecting breeding cowbird habitat selection. We compared distances of cowbird locations in the forest from the forest edge (“edge distances”) to distances of random forest locations in the entire landscape or within individual cowbird home ranges. We analyzed 1322 locations of 84 cowbirds across three landscapes. We found support for the landscape context hypothesis that breeding cowbird preference for forest edge varied with landscape context. Ninety percent of cowbird locations were within 150–350 m of forest edge, despite the overall availability of forest at greater distances from edge (as far as 500–1450 m) both within cowbird home ranges and the entire forested landscape. Cowbird preference for edge varied by landscape context largely due to differences in the availability of forest edge. In a highly fragmented forest cowbirds utilized the entire forest and likely viewed it as “all edge.” In less fragmented forests, cowbirds preferred edge. We consider how variation in cowbird edge preference might relate to patterns in host abundance, host diversity, and host quality because cowbird movements indicate they are capable of using forest farther from edges.
KeywordsBrown-headed Cowbird Edge effects Forest fragmentation Habitat selection Home range Illinois Landscape context Missouri Molothrus ater Neotropical migrant bird
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We thank G. Krause, S. Romano, S.␣Latta, E. Kinman, and A. Scheurlein for advice on our analyses. E. Gustafson, F. Huettmann, S. Latta, and D. Burhans commented on earlier drafts of the manuscript. We thank B. Edmond, L. Fray, T. Fredrickson, J. Gardner, B. Hartsell, C. Newbold, A. Taylor, and R. Weidel for assistance on the original radio-tracking study. This research was funded by the USDA Forest Service North Central Research Station, the Mark Twain National Forest, and the Shawnee National Forest. CAH was supported by a NSF BioInformatics Post-Doctoral Fellowship. This is PRBO contribution #1506.
- Burnham KP, Anderson DR (2002) Model selection and inference: a practical information-theoretic approach, 2nd edn. Springer-Verlag, New York, NY, USAGoogle Scholar
- Chasko GG, Gates JE (1982) Habitat availability along a transmission-line corridor in an oak-hickory forest region. Wildl Monogr 82Google Scholar
- Donovan TM, Thompson FR III, Faaborg J (2000) Cowbird distribution at different scales of fragmentation: trade-offs between breeding and feeding opportunities. In: Cooke T, Robinson SK, Rothstein SI, Sealy SG, Smith JNM (eds) Ecology and management of cowbirds. University of Texas Press, Austin, Texas, USA, pp 255–264Google Scholar
- Evans DR, Gates JE (1997) Cowbird selection of breeding areas: the role of habitat and bird species abundance. Wilson Bull 109:470–480Google Scholar
- Forman RTT, Godron M (1986) Landscape ecology. J.␣␣Wiley & Sons, New York, NY, USAGoogle Scholar
- Hanowski JM, Niemi GJ, Blake JG (1995) Seasonal abundance and composition of forest bird communities adjacent to a right-of-way in northern forests USA. In: Doucet GJ, Seguin C, Giguere M (eds) Environmental concerns of rights-of-way management. Hydro-Quebec, Montreal, Canada, pp 276–283Google Scholar
- Hochachka WM, Martin TE, Artman V, Smith CR, Hejl SJ, Andersen DE, Curson D, Petit L, Mathews N, Donovan T, Klaas EE, Wood PB, Manolis JC, McFarland KP, Nichols JV, Bednarz JC, Evans DM, Duguay JP, Garner S, Tewksbury J, Purcell KL, Faaborg J, Goguen CB, Rimmer C, Dettmers R, Knutson M, Collazo JA, Garner L, Whitehead D, Geupel G (1999) Scale dependence in the effects of forest coverage on parasitization by␣Brown-headed Cowbirds. Stud Avian Biol 18:80–88Google Scholar
- Litell RCC, Milliken GA, Stroup WW, Wolfinger RD (1996) SAS system for mixed models. SAS Institute, Cary, North Carolina, USAGoogle Scholar
- McGarigal K, Cushman SA, Neel MC, Ene E (2002) FRAGSTATS: spatial pattern analysis program for categorical maps. Computer software program available at: http://www.umass.edu/landeco/research/fragstats/fragstats.html
- Morris DL, Thompson FR III (1998) Effects of habitat and invertebrate density on abundance and foraging behavior of Brown-headed Cowbirds. Auk 115:376–385Google Scholar
- Ortega CP (1998) Cowbirds and other brood parasites. The University of Arizona Press, Tucson, Arizona, USAGoogle Scholar
- Robinson SK (1992) Population dynamics of breeding Neotropical migrants in a fragmented Illinois landscape. In: Hagan JM, Johnston DW (eds) Ecology and conservation of neotropical migrant land birds. Smithsonian Institution Press, Washington, DC, USA, pp 408–418Google Scholar
- SAS Institute (2000) Version 8.02. Cary, North Carolina, USAGoogle Scholar
- Stephens SE, Koons DN, Rotella JJ, Willey DW (2003) Effects of habitat fragmentation on avian nesting success: a review of the evidence at multiple spatial scales. Biol Conserv 111:101–110Google Scholar
- Thompson FR III (1994) Temporal and spatial patterns of breeding Brown-headed Cowbirds in the Midwestern United States. Auk 111:979–990Google Scholar
- Thompson FR III, Dijak WD (2000) Movements, home range, and habitat preferences of female Brown-headed Cowbirds in three midwestern landscapes. In: Cooke T, Robinson SK, Rothstein SI, Sealy SG, Smith JNM (eds) Ecology and management of cowbirds. University of Texas Press, Austin, Texas, USA, pp 100–109Google Scholar
- Thompson FR III, Robinson SK, Donovan TM, Faaborg J, Whitehead DR (2000) Biogeographic, landscape, and local factors affecting cowbird abundance and host parasitism levels. In: Cooke T, Robinson SK, Rothstein SI, Sealy SG, Smith JNM (eds) Ecology and management of cowbirds. University of Texas Press, Austin, Texas, USA, pp 271–279Google Scholar