Alaska Bird Observatory

Avian species diversity in the Noyes Slough, Fairbanks, AK: 13-26 May, 2000.

By: Anna-Marie Benson, Senior Biologist, Alaska Bird Observatory, P.O. Box 80505, Fairbanks, AK, 99708.

Submitted to: The Alaska Department of Environmental Conservation
Date: 30 June, 2000

Objective
The Noyes Slough was surveyed to determine the avian species using the slough and surrounding habitats (riparian shrub, forests, and cultivated substrates).

Methods
Surveys were conducted from 05:00 to 10:00 by canoe on 13 May and 19 May. Low water levels in the slough prevented further canoe surveys and an additional survey was conducted on 26 May from road-access points. Visual and auditory observations of birds detected in the Noyes Slough were recorded. Behaviors of birds were also recorded to determine the status of species based on the following categories:

Breeder - nesting behavior, nests, courtship behavior, or young were observed
Probable breeder - species observed at the same location twice; suspected, but not confirmed, breeding activity
Migrant - species observed only during peak species-level migratory movements
Unknown - species observed flying over or heard from Noyes Slough

The habitat the species was observed in was also recorded. The habitat could not be identified for species flying over or heard from a distance.

Results
Forty-three bird species were detected during surveys of Noyes Slough (Table 1). Five duck species were likely nesting on Noyes Slough, including Green-winged Teal, Mallard, Northern Pintail, Northern Shoveler, and American Wigeon. Lesser Yellowlegs, Solitary Sandpiper, Common Snipe, and Belted Kingfishers also bred in the slough.

Several species of birds were observed using the riparian shrubs bordering the slough: Alder Flycatcher, Gray-cheeked Thrush, Orange-crowned Warbler, Yellow Warbler, Northern Waterthrush, Wilson’s Warbler, Savannah Sparrow, Fox Sparrow, Lincoln’s Sparrow, and White-crowned Sparrow.

The shallow mud-flat areas of the slough were used by several species of shorebirds during migration: Semipalmated Plover, Semipalmated Sandpiper, Least Sandpiper, Pectoral Sandpiper, and Long-billed Dowitcher.

Few species were observed using the cultivated habitats in the lower portion of the slough; however, American Robins were commonly observed foraging in manicured lawns.

Discussion
Noyes Slough hosts a relatively diverse avifauna as a stopover site during migration. The water level in the slough dropped during peak shorebird migration in the Tanana Valley (18 May to 23 May), and shorebirds were observed foraging in the shallow mudflats in the upper portion of the slough. The value of this slough for migratory birds could not be evaluated in this study, but the mudflats could be important for Nearctic-Neotropic migrants during the final stages of their long-distance migration.

Several species were observed exhibiting nesting behavior along the slough. Belted Kingfishers appeared to be relatively abundant and many species of waterfowl were observed incubating eggs. The shrub and forest habitats along the river are used by several species of songbirds, many of which are also nesting in these habitats. In the lower portion of the slough, where non-natural habitats dominated the riverbanks, only one species, American Robin, was commonly observed. These data indicate that natural habitats along the slough are needed to maintain the current avian diversity in the slough.