Title: Seasonal bird traffic between Grand Teton National Park and western Mexico
Author: Cody, Martin L.;
Source: In: Ralph, C. John; Rich, Terrell D., editors 2005. Bird Conservation Implementation and Integration in the Americas: Proceedings of the Third International Partners in Flight Conference. 2002 March 20-24; Asilomar, California, Volume 1 Gen. Tech. Rep. PSW-GTR-191. Albany, CA: U.S. Dept. of Agriculture, Forest Service, Pacific Southwest Research Station: p. 32-45
Publication Series: General Technical Report (GTR)
Description: This paper presents data on variations in the breeding densities of birds in Grand Teton National Park, Wyoming, and evaluates these variations among years, habitats, and as functions of the migratory status of the breeding birds. Breeding opportunities certainly vary with the extremely variable weather conditions in the park year-to-year, and part of the variation in breeding density must be attributable to unpredictable on-site resources. A minority of the breeding birds is resident, but many species are long-distance migrants, and others make more limited winter movements of various distances. Most but not all of the migrants overwinter in habitats that are very dissimilar to those in which they breed. In some migrants the habitat range appears greater in wintering than in breeding habitats, and in others not. Some migrants winter syntopically with close relatives and others occupy winter habitats that lack resident relatives. I bring some perspective to these variations using winter and early spring observations of the same species (though not necessarily members of the same Teton populations) in western Mexico. In some instances in which Mexican wintering habitat similar to northern breeding habitat is available, wintering birds may be relegated to different habitats because of prior occupancy by resident species, often related species such as congenerics or even conspecifics.
Overwintering habitats are almost certainly at least as variable in survival opportunities as are the breeding habitats for reproduction. They also vary year-to-year in weather conditions that affect food supplies, and are co-occupied by resident species, some of which are close relatives to the winter visitors and have similar ecologies. The vagaries of overwinter survivorship and the transitions of the birds between breeding and wintering grounds constitute a broad and poorly understood category of off-site factors for conservationists and resource managers whose chief source of information is the breeding populations. A much closer integration of research on breeding and wintering populations will be required before useful conservation strategies for migrant bird opulations can be devised. This integration, through organizations like Partners in Flight, must become a research priority in the future.
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Cody, Martin L. 2005. Seasonal bird traffic between Grand Teton National Park and western Mexico. In: Ralph, C. John; Rich, Terrell D., editors 2005. Bird Conservation Implementation and Integration in the Americas: Proceedings of the Third International Partners in Flight Conference. 2002 March 20-24; Asilomar, California, Volume 1 Gen. Tech. Rep. PSW-GTR-191. Albany, CA: U.S. Dept. of Agriculture, Forest Service, Pacific Southwest Research Station: p. 32-45
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