Deployment Summary Table

HWI has been banding and monitoring raptors during migration at a network of sites in the western United States for roughly 20 years. These long-term studies have allowed HWI to begin detecting trends in the numbers of raptors migrating through the region. However, for migration counts to be considered useful for monitoring or management of raptor populations, we need to quantify flyway fidelity (i.e., do individual birds use specific flyways consistently across seasons and years?), identify the origins of migrant raptors moving by specific count sites, and understand the relationship between migration counts and underlying population trends (i.e., how quickly and at what resolution can we detect actual changes in populations using migration counts?).

To help answer some of these questions, HWI began a satellite-tracking program in 1999 at migration sites in Nevada and New Mexico, and expanded the project to Washington in 2001, Oregon in 2002, and Wyoming in 2004. In general, the information we are gathering through satellite tracking is essential to enable accurate interpretation of the population trends we document through our migration counts. Moreover, the detailed information we learn about patterns of habitat use will help us tailor our Conservation Strategy to better meet identified habitat conservation needs. More specifically, the following are the major objectives of our ongoing satellite-tracking program:

• Delineate migratory flyways: The band-return information that we have collected during the past 20 years, combined with data collected in California by the Golden Gate Raptor Observatory, has already helped us broadly outline three flyways in western North America: Pacific Coast, Intermountain, and Rocky Mountain (Hoffman, Smith, and Meehan. 2002. Breeding grounds, winter ranges, and migratory routes of raptors in the Mountain West. Journal of Raptor Research 36:97-110). Cataloging band returns has yielded valuable information about the overall boundaries of regional flyways, but band returns usually yield little information about the specific pathways followed by individual birds (i.e., typically they connect only two points along a migration pathway: the original banding location and the recovery location). In contrast, satellite tracking enables detailed mapping of such pathways, thereby yielding more information about important habitat areas and the spatial and temporal dynamics of movements within flyways.
• Determine fidelity to migration flyways between seasons and years: Satellite tracking will help us quantify flyway fidelity for individual birds by allowing us to track their movements across both spring and fall seasons and multiple years. Such information is essential to establish whether the sample of migrants we observe at a given site remains consistent from year to year. This is a necessary condition for migration counts to serve as a reliable indicator of long-term population trends.
• Identify connections between specific breeding, migratory, and wintering populations: Locations derived from satellite tracking will help us delineate the breeding and wintering ranges of birds that pass through our migration sites. For long-distance migrants and species with broad ranges, this may not help in validating migration counts as a useful tool for monitoring local or regional populations. However, for species with limited migration or dispersal distances, satellite tracking may help identify specific populations that can be monitored more easily during migration than during the breeding season. And even for long-distance migrants, results from the study may pinpoint specific wintering areas that may prove useful for monitoring or for identifying critical habitat in need of conservation.

All of the transmitters we use are programmed with specific "duty cycles" to prolong battery life. Our initial fall 1999 deployment included transmitters that experienced a problem called “battery passivation.” This resulted in no transmissions during winter and summer periods when we had the transmitters programmed to transmit only once every 8-10 days. Fortunately, however, most units continued to function properly during migration periods when the transmission cycle was more rapid, and we subsequently obtained 1.5–2.5 years of good location data from our first three Red-tailed Hawks outfitted in the Goshute Mountains, NV. We were less fortunate with our first two Golden Eagle units, which both failed completely by spring 2000. Given these problems, we had all undeployed transmitters and two recovered goshawk transmitters refurbished free of charge with new batteries, shorter off periods, and new power management software in hopes of solving our transmission problems. We also had one of the two eagle transmitters replaced free of charge. Since then, all units we have deployed have included the modified hardware, software, and duty cycles, and thus far we have had few additional problems.

Another important feature of our program is that, thanks to a handheld ARGOS receiver that we purchased in 2000, we have thus far achieved nearly 100% success in recovering transmitters from birds that have died within the U.S. and continued to transmit. We are able to have all such recovered transmitters refurbished for a fraction of the cost of buying new ones, so the effort expended is well worth it.

Summaries of our tracking results for all birds outfitted to date, along with detailed tracking maps, can be accessed by following the links at the top of this page. The summaries are organized by deployment season, then by migration site and species within sites.

HawkWatch International would like to thank the following individuals and organizations for their generous support of this important project:

• National Fish and Wildlife Foundation
• USGS Biological Resources Division - Patuxent Wildlife Research Center
• Bureau of Reclamation – Upper Colorado Regional Office
• US Fish and Wildlife Service, Region 2
• M. J. Murdock Charitable Trust
• La Salle Adams Fund
• Dr. Ezekiel R. & Edna Wattis Dumke Foundation
• W. C. Swanson Family Foundation
• Schaffner Family Foundation
• Mountaineers Foundation
• JEPS Foundation
• Siganls of Spring
• North Star Science and Technology / American Bird Conservancy
• Dr. Carol McIntyre, Denali National Park, Alaska
• Mr. George Perkins, Jr.
• Jennifer and Randy Speers
• Dr. David Chuljian; Dr. Kay Millar
• and all sponsors of our satellite-tracked raptors.

Thank You!