Breeding and winter ecology of raptors from Grand Teton National Park.

Authors(s): D. Craighead, R. Smith and S. Cain

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Publication Date: 0000-00-00

Type: progress report

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Abstract: Objectives Research over the past 55 years has shown that the reproductive rate of Red-tailed hawks, a nearctic migrant, in Grand Teton National Park is well below population replacement level. We are attempting to determine if events contributing to low reproductive success occur when the birds are in Mexico and Latin America during the winter portion of the annual cycle. Our goals are: 1) to continue raptor census efforts in GRTE; and 2)to determine if events contributing to low reproductive success occur when the birds are in Mexico and Latin America during the winter portion of the annual life cycle. Findings and Status A 54-year comparison of the diversity and density of breeding raptors in Grand Teton National Park shows a 36% decline in species diversity (from 11 species in 1947, to 7 species in 2001) and a 56% decline in the number of breeding pairs. Notably, we have documented an 80% increase in the number of nesting common ravens and a decrease in nesting forest raptors such as red-tailed hawks, goshawks, Cooper's hawks, and owls since 1947. Research over the past 10 years has shown that the reproductive rate of Red-tailed hawks in Grand Teton National Park is well below population replacement level. If a generalist species such as the red-tailed hawk is in a long-term trend of decline, then other more sensitive species may also be in decline, and the sustainability of the greater natural ecosystems of which they are inhabitants is in reasonable doubt. We have tracked the migratory routes and specific wintering areas of 16 adult Red-tailed hawks from Grand Teton National Park over the past three years. Each bird was fitted with a 32-gram satellite transmitter attached with a backpack-type harness. We are using the Argos satellite-based location and data retrieval system to locate tagged birds. We have documented departure and arrival dates, migration routes, rates of travel and stop over areas. We are analyzing daily migration movements in relation to weather systems. We have made five field trips to Mexico and obtained location data for eleven winter use areas. During each visit to hawk winter-use areas, we have conducted rapid environmental assessments, met with government, NGO, and private individuals to build a cooperative research network, and identified graduate students who are capable of participating in this cooperative research project.

Keywords: Grand Teton National Park, breeding, animal studies, raptor, bird, Aves, ornithology, animal, Swainson's hawk, Buteo swainsoni, red-tailed hawk, Buteo jamaicensis, common raven, Corvus corax, Corvidae, nest, nesting, habitat, goshawk, Accipiter gentilis, Cooper's hawk, Accipiter Cooperii , owl, accipiter, population , human activity, radio collar