Alaska Science Center

Arctic Warbler, Phylloscopus borealis kennicotti

High-Priority Species List

The Alaska subspecies of Arctic Warbler is the second highest ranking bird for early detection of the Asian H5N1 virus in North America. It overwinters in the epicenter of Asian H5N1 outbreaks in southeast Asia and Indonesia, where it is abundant in shrub and forest habitats around farms and homes. Arctic Warblers are thus likely to become infected with Asian H5N1 through direct contact with both wild and domestic birds in Asia and carry it to Alaska where the entire subspecific population of 2,700,000 birds breeds.
In Alaska, the Arctic Warbler is one of the most abundant birds in shrub habitats on the Seward Peninsula, northern Bristol Bay, and central Alaska and central Brooks ranges. Areas used by Arctic Warblers on the Seward Peninsula and central Brooks Range also have some of the highest breeding densities of Eastern Yellow Wagtails (Moticilla tschutschensis), Bluethroats (Luscinia svecica), and Northern Wheatear (Oenanthe oenanthe), all of which are among the highest ranking species for detection of Asian H5N1 in North America. Thus several priority species could be sampled incidental to work focused on Arctic Warblers. Furthermore, the shrub habitat used by Arctic Warblers support some of the highest densities and greatest numbers of species of breeding passerines in the state. Thus, the potential is high for the spread of Asian H5N1 from infected Arctic Warblers to co-occurring breeding bird species that migrate through the Americas, such as Gray-cheeked Thrush (Catharus minimus), another high ranking species for detection of Asian H5N1 that reaches its highest breeding densities in these habitats.

Where abundant, both adult and juvenile Arctic Warblers have been commonly captured and banded in mist-netting efforts aimed at estimating annual survival and productivity in Alaska. For example, from 1992–2001 a mist-netting station run in Denali National Park and Preserve (Denali NPP) as part of the Monitoring Avian Productivity and Survivorship program (MAPS) captured an average of approximately 27 adult and 12 juvenile Arctic Warblers per year. Similarly, a recent study of Arctic Warblers in the central Alaska Range by the Alaska Bird Observatory captured 40 adults in 2005. Thus, a crew of 2 technicians operating five MAPS stations placed in appropriate habitats could capture approximately 140 adult and 60 juvenile Arctic Warblers during a single breeding season in a single geographic area (e.g., Denali NPP). Multiplying this effort across five road-accessible areas with high densities of breeding Arctic Warblers (Dillingham, Nome, Denali NPP, Denali Highway, and c. Brooks Range), five crews could capture in a single breeding season approximately 700 adult and 300 juvenile Arctic Warblers for sampling of actively shedding Asian H5N1.

Such sampling would not only provide 95% power of detecting Asian H5N1 in approximately 1.5% of the population of adults and juvenile Arctic Warblers for each geographic area, but also ensure robust sampling of adults returning from throughout the species wintering range in southeast Asian and Indonesia. Furthermore, incidental capture of Gray-cheeked Thrushes, Eastern Yellow Wagtails, Bluethroats, and Northern Wheatear would help achieve sampling goals for early detection of Asian H5N1 for these species in Alaska. Incidental captures of Gray-cheeked Thrush in particular would likely result in sampling of = 200 breeding adults and juveniles at no additional costs in sampling.

We will capture a target sample of 140 adult and 70 juvenile Arctic Warblers at each of five road-accessible areas where the species reaches its highest breeding densities in Alaska. This will result in an estimated 700 adults and 300 juveniles captured and sampled for actively shedding Asian H5N1 in 2006. Geographic areas for sampling will include, in order of preference Denali Highway, Denali NPP, Nome, Dillingham, and central Brook Range. In each geographic area one crew of 2-3 people will operate five stations, each with 15 mist nests distributed in appropriate habitats over a 10-ha area, from 10 June-8 August 2006. Following the protocols of the MAPS program, mist nests at each station will be open for 6 h starting at 0500 (or local sunrise if later) during one day for each of six consecutive 10-d periods. All captured Arctic Warblers will be aged, sexed, swabbed for actively shedding avian influenza virus, measured, banded, and released. Additionally, all other species of birds captured in mist nets incidentally to capture of Arctic Warblers will be similarly handled and sampled. Personnel will follow the protocols of the National Wildlife Health Center (NWHC) to protect themselves from Asian H5N1 and to collect, store, and ship samples. Cloacal swabs from Arctic Warblers and other target species captured incidentally to work on Arctic Warblers will be sent directly to the NWHC for screening for Asian H5N1. Cloacal swabs from non-target species will be stored by the U.S. Fish and Wildlife Service in Anchorage and will be made available to the NWHC for screening upon request. This work will be coordinated with other capture work on Eastern Yellow Wagtail, Bluethroat, and Northern Wheatear in the Askinuk Mountains, Alaska.

No. of samples: 700 adults, 300 juveniles
Sampling locations: Denali NPP, Denali Highway, Nome, Dillingham, central Brooks Range
Sampling timeframe: 10 June-8 August
Sample demographics: Adults and juveniles, males and females
Methods of capture: Live capture, release
Other targeted species: Eastern Yellow Wagtail; Bluethroat; Northern Wheatear; Gray-cheeked Thrush; Swainson’s Thrush; Orange-crowned, Blackpoll, and Wilson’s warblers; American Tree, Fox, and White-crowned sparrows; Common and Hoary redpolls (target species for surveillance of Asian H5N1 included in bold)

U.S. Fish and Wildlife Service
Migratory Bird Management
Contact: Steven M. Matsuoka

Togiak NWR
Contact: Rob MacDonald

U.S. Geological Survey
Alaska Science Center
Contact: Colleen M. Handel

Bureau of Land Management’s Northern Alaska District
Contact: Deb Nigro

National Park Service
Denali National Park and Preserve
Contact: Carol McIntyre

Alaska Bird Observatory
Contact: David Shaw

Institute for Bird Populations
Contact: David F. DeSante
Distribution map of Arctic Warbler

Ranking Score: 17.0

Asian H5N1 ranking criteria for Arctic Warbler, Phylloscopus borealis kennicotti.

Total of partial
contact with Asia1
Contact with
known "hot spot"2
Habitat used in
Pop. in Alaska4
Can samples be
Winters in Myanmar, Thailand, Philippines south to Andaman Is, Malay Penin, and Indonesia east to Moluccas
s.e. Asia and Indonesia
Terrestrial. Wooded habitats, cultivated areas, grasslands, gardens, and mangroves
Approximately 2,700,000
Most abundant breeding bird in many locations. Very easy to capture during breeding and migration. Already capture 30-45 birds per year during breeding
Image of Arctic Warbler, photo by A. BO