The Alaska Bird Observatory (ABO) has operated a large standardized mist-netting station at Creamer’s Field Migratory Waterfowl Refuge in Fairbanks, Alaska from 1992-2001. The objectives of the netting program are to capture and band migrating passerines to examine: 1) population dynamics, 2) the phenology of migration, 3) timing of life history events (e.g. migration, reproduction, molt, juvenal dispersal, and seasonal differences in body condition), and 4) habitat use. Additional objectives are 1) provide public education programs relating to avian ecology and conservation, 2) involve volunteers from the community in scientific research, and 3) provide training in mist-netting and banding techniques to biologists from throughout Alaska.

Approximately 150 migration-monitoring stations are located throughout North America. Creamer’s Field Migration Station (CFMS) is the northernmost station in the Western Hemisphere. The location of this study site is near the northern and western limits of the breeding range of several species of boreal forest landbirds that have undergone population declines in other portions of their geographic range. Therefore, CFMS is in a unique position to provide crucial information for studying population trends in migrant passerines. The migration station has also become a popular destination for local school groups, naturalists, bird enthusiasts, and international visitors.

Data provided from CFMS support the goals and objectives of the Alaska Department of Fish and Game and Partners in Flight (PIF). PIF is a comprehensive Neotropical migratory bird conservation program of applied management, monitoring, and research implemented cooperatively by state and federal governments, industry, conservation organizations, and academia from North, South, and Central America. Additionally, data from CFMS support the goals and objectives of the Bureau of Land Management (BLM) nongame migratory-bird habitat conservation program. Finally, the ABO education programs are in line with the one of the legislative purposes for which Creamer’s Refuge was established; to provide the opportunity to view, photograph, and study various species of plants, wildlife and geological features typical to interior Alaska (AS 16.20.039). To accomplish this objective, the Alaska Department of Fish and Game (ADFG) may authorize the use of Refuge lands and facilities by other organizations for conducting educational and research programs.

METHODS

Netting Protocol
Field methods have remained relatively constant during ten years of migration banding at CFMS. This year, 34 standard 12m and 2 standard 6m nets were opened at sunrise and closed six hours later, or as late as 13:30 h, between 15 July and 23 September (weather permitting). Mist nets were operated on alternate days from 25 to 29 September. Changes in the timing of netting were effected after data analysis showed no difference in daily timing of captures during fall migration. The ABO Scientific Advisory Council approved the changes. In previous years, nets have remained open for seven hours daily; the decrease in net time this year allowed ABO to maintain worker schedules of 8 hours daily. For a detailed description of the methodology see Pogson et al. (1996).

Relative Abundance
First-time captures of individuals were used in the analysis of abundance (newly banded birds, returns, foreign recoveries, and unbanded dead birds). Birds banded in spring or summer and recaptured in fall were not included, as they were assumed to be local breeders. Captures prior to 25 July were excluded, as they were likely breeding birds or local dispersing juveniles (based on molt and plumage), rather than migrants.

Daily capture rates (birds/1000 net hours) were calculated for each species. The annual population index was calculated as the geometric mean (arithmetic mean of the transformed counts, back transformed) of all daily migration counts for 19 abundant species (more than 10 individuals captured each fall). A constant (one) was added to each daily capture rate to compensate for counts of zero. Geometric mean (compared with arithmetic mean) is relatively insensitive to occasional unusually high counts while still reflecting small increases or decreases that are consistently present in daily counts across the entire migration season (Dunn and Hussel 1995).

RESULTS

Summary 2001
We banded 2,485 birds of 31 species during the fall migration of 2001 (Table 1). Nets were operated for approximately 11,821 net hours (one 12m net open for one hour). As in previous years, the most abundant species captured were Yellow-rumped (Myrtle) Warblers, Orange-crowned Warblers, American Tree Sparrows, and Dark-eyed Juncos. These species comprised 61% of all birds banded. However, the population index of American Tree Sparrows was at a ten-year low; also at ten-year lows were the indices of Yellow Warblers and Wilson’s Warblers (Table 2). Species that had been at record lows last year (Alder Flycatcher, Gray-cheeked Thrush, Swainson’s Thrush, American Robin, and Fox Sparrow) did not decline further. Notable captures included a Yellow-Bellied Flycatcher, a Merlin, and a Northern Goshawk.

One unusual aspect of the 2001 fall field season was the occurrence of a deliberate act of vandalism during the evening/early morning of September 4 or 5. While small destructive acts have happened from time to time, especially during the Tanana Valley State Fair in August, this particular act resulted in the methodical destruction of 30 nets. Almost every net (except nets 7-10, 18 and 19) was cut twice. State troopers investigated the scene, and mist netting resumed about an hour later than usual. While the location of CFMS near a highly populated area is one of its advantages in terms of public education, the concomitant risks of vandalism and criminal interference must also be addressed.

EDUCATION

Public Demonstrations
ABO worked cooperatively with the Alaska Department of Fish and Game to conduct environmental education programs for school, community, and tour groups. A curriculum designed by ABO was utilized to teach and inform students about the Alaska Bird Observatory, its mission, and the natural history of the Creamer’s Field Migratory Waterfowl Refuge. Visitors to the banding station were greeted by staff, interns, and volunteers and presented with a banding demonstration relating to avian ecology and conservation. During the 2001 field season approximately 2,255 individuals visited the CFMS banding station. For more information, see the forthcoming education report.

Training Program
WWe operated a training program for wildlife professionals and ABO interns from 16 July to 27 July. The program included hands-on training in methods of mist netting and banding passerines. Additionally, it included a lecture component that focused on objectives of netting programs, aging birds by molt limits, and identification of species and plumages not observed in the field. We trained four interns and four biologists during this ten-day program. The biologists were employees of the U.S. Fish and Wildlife Service and the Denali Institute.

Volunteers
Fifty-three people volunteered at CFMS during the 2001 field season, contributing 1,555 hours of volunteer time to ABO. Volunteers at the banding station received training in removing birds from mist nets, net maintenance, bird identification, recording data, and handling birds for public demonstrations.

Internship
One high school student, two recent college graduates, and one graduate student received bird-banding training and experience. Each intern learned to band birds safely and efficiently, collect standard data, and enter the data accurately. Proper station maintenance and management were emphasized, as well as other skills which are required for North American Banding Council Bander certification.

Meetings and Certifications
On August 15-17, Senior Biologist Anna-Marie Benson presented a poster at the American Ornithologists’ Union conference in Seattle, Washington, entitled "A High-latitude Circus: Time-energy Juggling and the Appearance of Super Phenotypes among Long-distance Avian Migrants." This work focused on results garnered from CFMS data. In addition, Benson participated in an international meeting on migration monitoring at the conference.

On September 21-23, Migration Program Manager Jacqueline Weicker attended the Western Bird Banding Association’s annual meeting in Spokane, Washington. Prior to the meeting, on September 19-20, she was evaluated by members of the North American Banding Council as part of a certification process. This involved a test of field skills such as identifying and processing birds, net set-up and placement, station management, and other aspects of banding. A written test covering regulations and ethics was administered, as well as an oral exam on avian biology and teaching skills. She passed at both the Bander and Trainer levels. In addition, she presented papers at the WBBA meeting on "Migration Monitoring in Alaska: Perspectives from High-latitude Sites" and "Sexing Wilson’s Warblers: Looking Beyond the Cap," and participated in a roundtable discussion on migration.

Specimen Preparation
All interns and banding trainees received instruction in preparing scientific specimens from salvaged birds. Weekly workshops were held in September and October, during which interns and local volunteers prepared study skins to build the Observatory’s teaching collection (permitted under USFWS, #MB025972-0). These specimens are already being used in educational programs for the public and will serve in the training of interns and station volunteers in the future. Some 35 specimens of 22 mostly local species have been prepared (Table 3). This synoptic collection is a valuable representation of different species, dimorphic plumage, and molt patterns.

DISCUSSION

Capture Trends
Analyses of data from standardized mist-netting stations indicate that migration-monitoring stations can provide information on the abundance and survivorship of migratory bird populations (Chase et al. 1997, Dunn et al. 1997, Johnson and Geupel 1996). The northern location of Creamer’s Field Migration Station allows us to examine the initial phase of autumn migration in Nearctic-Neotropic passerines. A more in-depth analysis of these data will answer questions relating to passerine migration that cannot be examined elsewhere in North America.

Capture rates of Gray-cheeked Thrushes and Swainson’s Thrushes have declined during the 10-year spring netting period at Creamer’s Field (Benson 2001), and were at a nine-year low during the fall of 2000 (Shaw et al. 2000). Autumn netting at CFMS did not reveal further declines in either of these Catharus thrushes. Capture rates of Wilson’s Warblers declined during the ten years of spring netting at CFMS, and are at a ten-year low during this fall migration period. This species warrants monitoring next year though point counts and netting studies to see if these declines continue.

Management Implications
Understanding movements and population dynamics of passerines has become an international concern due to recent documentation of population declines throughout North America (Rappole and McDonald 1994, Askins et al. 1990). Establishing baseline population data for different species is crucial in order to take management and conservation actions before a species becomes threatened or endangered. Furthermore, baseline monitoring allows land managers to set management priorities (e.g., habitat preservation) based on scientific data. Long-term data collected at CFMS is important for understanding population dynamics of migratory songbirds in interior Alaska.

RECENT PUBLICATIONS

Benson, A.M. and K. Winker. 2001. Timing of breeding range occupancy among high-latitude passerine migrants. The Auk 118(2): 513-519.

ACKNOWLEDGEMENTS

We gratefully thank all ABO members, volunteers, staff and interns for their time and dedication. The Alaska Bird Observatory Scientific Advisory Council has provided invaluable expertise and guidance in research design. We also thank John Wright and Mark Ross of the Alaska Department of Fish and Game for their time and support.

This project was funded primarily by: Alaska Department of Fish and Game (Contract # IHP-01-016); Bureau of Land Management (Cooperative Agreement #1422L320A7-2005); ABO members; ABR, Inc.; Phillips Alaska, Inc.; Arctic Audubon Society; and American Seafoods Company. Additionally, the Alaska Department of Fish and Game provided significant in-kind support.

LITERATURE CITED

Askins, R.A., J.F. Lynch, and R. Greenberg. 1990. Population declines in migratory birds in eastern North America. Curr. Ornithol. 7: 1-57.

Benson, A-M. 2001. Creamer’s Field Migration Station: Spring Report 2001. Unpublished report submitted to the Alaska Department of Fish and Game and the Bureau of Land Management.

Chase, M.K., Nur, N. and G.R. Geupel. 1997. Survival, productivity, and abundance in a Wilson’s Warbler population. Auk 114: 354-366.

Dunn, E.H., D.T. Hussell, and R.J. Adams. 1997. Monitoring songbird population change with autumn mist netting. J. Wildl. Manage. 61(2): 389-396.

Johnson, M.D. and G.R. Geupel. 1996. The importance of productivity to the dynamics of a Swainson’s Thrush population. Condor 98: 133-141.

Pogson T.H., A-M. Barber, S.L. McDaniel, and S.K. Springer. 1996. Creamer’s Field Migration Station fall summary report. Unpublished report submitted to the Alaska Department of Fish and Game.

Rappole, J.H. and M.V. McDonald. 1992. Cause and effect in population declines of migratory birds. Auk 111: 652-660.

Shaw, D.W., A-M. Benson, A. Eberhart, C. Topp, and M. Schuiteman. 2000. Creamer’s Field Migration Station: Fall Report 2000. Unpublished report submitted to the Alaska Department of Fish and Game.