Alaska Bird ObservatoryAlaska Bird ObservatorySince 1992, the Alaska Bird Observatory (ABO) has conducted research in Denali National Park and Preserve (DNP&P). The National Park Service (NPS) currently does not have an existing, systematic inventorying and monitoring program for breeding birds. Because of this, DNP&P was selected as one of four national parks to develop protocols for monitoring long-term avian fluctuations in our national parks. Through a contract with NPS, ABO conducts research to develop protocols that quantify annual variation in relative abundance of landbirds found in the park.
We modeled our protocols after Butcher et al. (1992) who proposed national guidelines for all avian monitoring programs for all federal agencies. They indicated that monitoring programs should be designed to have a 90% probability of detecting a cumulative 50%, or 2.7345% annual, decline in a species over a 25 year period. To reach this goal, the field work for the last six years included two primary objectives: 1) Quantify interannual variation in the abundance of landbirds along the DNP&P road corridor using on-road point counts; and 2) Quantify interannual variation in the detection probabilities of breeding landbirds using off-road point counts in spruce forests.
The on-road counts consisted of four Breeding Bird Survey-styled censuses along the park road that were surveyed at least twice a year. Each on-road census was 39.2 km long with 50 point count stations spaced 0.8 km apart. To conduct the off-road censuses, we utilized a technique developed by a Boreal Partners in Flight working group. These off-road routes comprised 12 point count stations spaced 250 m apart and were conducted in spruce forests only. There are nine of these routes within the park.
From the off-road censuses, we discovered that the relative abundance of most species were notably similar between years. Other species, like White-winged Crossbill and Redpoll spp., both permanent residents, exhibited dramatic fluctuations. Rare species showed the most annual variation by virtue of their not being detected some years.
The analyses revealed that, by utilizing both censuses, we would be able to monitor those species that occurred at > 14% of all point count stations (this assumes using frequency to monitor population trends and an exponential rate of decline). Eleven species met this criteria on off-road censuses: Gray Jay, Swainson's Thrush, American Robin, Varied Thrush, Orange-crowned Warbler, Yellow-rumped Warbler, Wilson's Warbler, American Tree Sparrow, Dark-eyed Junco, White-crowned Sparrow, and Redpoll. In addition, Boreal Chickadee, Ruby-crowned Kinglet, and White-winged Crossbill occurred at 14% of all stations at least one year of this study, indicating that at least 14 species could be monitored using the above mentioned protocols. At least 12 species could be monitored with 100 independent point count stations along on-road routes based on data collected during on-road route #1. At higher elevations, such as route #2, the Arctic Warbler could be monitored. Routes #3 and #4 are at the west end of the park, which has more diverse habitats that allow for the Alder Flycatcher and the Gray-cheeked Thrush to be systematically monitored.
Paton, Peter W. C. and Stephen K. Springer. 1997. Monitoring landbirds in Denali National Park utilizing on-road and off-road point counts. Annual Report to the Nat. Park Service.
Paton, Peter W.C. and Thomas H. Pogson. 1996. Relative abundance, migration strategy, and habitat use of birds breeding in Denali National Park, Alaska. Canadian Field-Naturalist 110: 599-606. (Contact birds@polarnet.com for reprints of this article)
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