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Monitoring Migrant Shorebirds in the Western United States: a pilot study
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During the past few years, enormous progress has been made in developing national and regional plans for monitoring shorebirds. Shorebirds have been identified as one of four major avian programs under the newly formed North American Bird Conservation Initiative (NABCI). A U.S. Shorebird Conservation Plan has been prepared by several dozen shorebird experts. The U.S. Plan includes a proposed national monitoring program. Regional shorebird plans have also been prepared under the auspices of the U.S. Plan, and each of them calls for regional monitoring programs. Thus, a rich infrastructure, almost undreamed of just a decade ago, now exists for developing and implementing shorebird monitoring programs.
The International Shorebird Survey (ISS) in the eastern and central United States and the Maritimes Shorebird Survey in southeastern Canada have been conducted for more than 20 years and provide a wealth of information about how to survey shorebirds in these areas. Much less is known about how to conduct long-term surveys in the intermountain west and the Pacific Coast. Accordingly, Regions 2, 3 and 6 of the US Fish and Wildlife Service and the USGS Forest and Rangelands Ecosystem Science Center are initiating a pilot study designed to conduct shorebird surveys in the western United States and to lay the foundation for long-term, integrated surveys covering the entire United States and southern Canada.
The National Shorebird Plan established national and regional goals for the shorebird monitoring program. The national goals are:
- Statistically valid monitoring of long-term, species-specific population trends.
- More precise estimates of the size of species’ total populations.
- Monitoring shorebird use of major staging, migration, and wintering areas in the United States and Canada.
- Ensuring that shorebird population information is effectively integrated into the national bird conservation planning and implementation process.
Goals 1, 3, and 4 can be addressed at major stop-over sites. They require that the surveys be carefully designed so that statistically valid inferences may be made and so that the information derived can be integrated with other major programs being carried out under the North American Bird Conservation Initiative. It is also essential that the surveys at each site be carried out over the long term, not for just a few years.
The Intermountain West and North Pacific Regional Plans establish broad goals and strategies consistent with the national goals. Both Plans emphasize that the monitoring and assessment plan should provide for meeting local needs as well as addressing regional and national needs.
The general goal of the shorebird survey is thus to monitor numbers of shorebirds at major stop-over sites, with specific survey areas being chosen to include the most heavily used areas at each site and any areas that are of special interest to local managers.
The regional plans of the Shorebird Conservation Plan identify major shorebird stop-over areas. Within each of these and several other areas (Fig. 1, Table 1), we are defining "sites" that require approximately 3-4 hours to survey. A detailed description of each site is being prepared with assistance from local biologists. The description includes a map delineating the area to be covered on the surveys and provides information on access and other advice useful in carrying out the survey. Site borders are established to include all areas likely to be used (if suitable areas vary between years) including anticipated new habitat that may be created in the future. An indication of species and numbers likely to be found is also provided. In defining the survey area, we attempt to balance thorough coverage of the site with insuring that the birds are readily visible so that observer differences will be minimal.
At each site, two periods of not more than 30 days each will be identified during which the survey will be carried out. These periods will generally fall during spring and fall migration but will be adjusted for sites used by staging and wintering birds as seems best to the local biologists. Within the 30-day period, survey times may be restricted to particular times of day or conditions defined by weather, tide height, or any other factor that will make the counts more stable and meaningful. Such conditions, however, must be chosen with care because once they are defined it will be important to maintain them as a survey requirement.
During each 30-day period, and during whatever additional constraints are defined for the surveys, the objective of the survey is to estimate the average number of shorebirds present at the site. This can be accomplished with a single survey, or with several surveys. Survey times, however, must be chosen in advance, or at least independently of how many shorebirds are present at the site. Thus, making surveys because one knows that weather conditions have brought a large flight of shorebirds into the area would not provide a reliable estimate of the average number of birds present at the site during the survey period. Furthermore, as observers change their selection process might change altering the count in ways independent of changes in numbers actually present.
For information about survey goals or design contact Dr. Jonathan Bart (jon_bart@usgs.gov or 208-426-5216).
Shorebird Monitoring Sites
Table 1. Sites currently in the pilot study. We are contacting all of the sites and expect most of them, or others in their place, to participate in the Survey this spring and summer.
Jon Bart
Address: USGS Snake River Field Station
Address: 970 Lusk Street
Address: Boise, ID 83706
Phone: 208-426-5216
E-mail: jon_bart@usgs.gov
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