Important Bird Areas

Mendenhall Wetlands

Alaska

The Mendenhall Wetlands complex has the third greatest acreage of vegetated tidal salt marsh of all estuaries in Southeast Alaska. It is widely acknowledged to be one of the key migratory waterfowl and shorebird stopover locations of coastal Alaska. This 1,820 hectare area is bordered by coniferous forest and open salt water. It includes supratidal meadows, a high salt marsh dominated by grasses and a low salt marsh dominated by Lyngbye sedge. Within the salt marsh are mud and sand flats with numerous intertidal channels. One major river (Mendenhall) bisects the area and 14 freshwater streams flow into the wetlands. All of these rivers and streams support Pacific salmon and other fish which contribute to the richness of the area. The area also contains several freshwater and brackish ponds.

Ornithological Summary

A total of 230 species of birds has been documented to occur on the Mendenhall Wetlands, as of January, 2002 (Armstrong & Gordon 2002). This represents 77% of the 300 bird species seen for the entire Juneau Area - from Taku Inlet to Berners Bay (van Vliet et al. 2003), and 69% of the 335 bird species seen for all of Southeast Alaska ? between Dixon Entrance and Yakutat (Armstrong and Gordon 2001).
The Mendenhall Wetlands are of outstanding value to waterbirds, as well as certain grassland and wet-meadow songbirds and raptors. It is used significantly both for resting, and foraging for food, most notably in the network of brackish sloughs. Throughout early spring and early fall, many species of ducks, notably including dabbling ducks, and many taxa of geese, favor the area. From about April 26 through May 23, a large number of shorebirds pass through. The southward shorebird migration is much longer and less regular, lasting from late June to early October. At that season, except for unpredictable brief big flights, the birds are spread widely amidst the tall grasses and sedges, thus being usually much less observable than in the spring.
We have observed 36 species of waterfowl, plus 2 distinctive subspecies (Aleutian Cackling Goose and Eurasian Green-winged Teal). Recorded are 41 species of shorebirds, plus 1 distinctive subspecies (Pribilof Rock Sandpiper). Recorded also are 17 species of Larids (gulls, terns, and one jaeger). The wetlands are also valuable during migrations, primarily April and late August into early November, for a great variety and moderate numbers of raptors, including Short-eared Owls.
Of the 72 species and subspecies of shorebirds addressed in the U.S. and Canada National Shorebird Plans, almost half (49%) have experienced apparent population declines since 1970. For 17 of these taxa, all but one of which occurs on the Mendenhall Wetlands, the declines are statistically significant (Andres & Gill 2000).
The numbers of birds occurring on the wetlands can be quite large. In every month except June, over 2,000 birds have been counted in the area at one time. During spring migration, in April and May, the total number of birds could reach a daily high of 16,000+ individuals. By species the greatest number (over 1,000 at one time) have been Canada Goose, Mallard, Surf Scoter, Ruddy Turnstone, Surfbird, Western Sandpiper, Bonaparte?s Gull, Mew Gull, Glaucous-winged Gull, and Northwestern Crow. Substantial numbers (over 500 at one time) of other species have also been documented: Northern Shoveler, Greater Scaup, White-winged Scoter, Semipalmated Sandpiper, Least Sandpiper, Pectoral Sandpiper, Dunlin, Short-billed Dowitcher, and Common Redpoll.
These daily high counts only represent a small fraction of the total number of individuals that utilize the Mendenhall Wetlands in any given year. For migratory shorebirds this number could be quite high, especially considering that the daily turnover is rapid; shorebirds, for example, may spend only one to three days at resting and refueling sites on their way to their northern breeding grounds (Iverson et al. 1996).
An excellent database of bird observations exists for the Mendenhall Wetlands. This database includes 10,881 bird observations made since 1986. The database is included on a CD with the report by Armstrong et.al. 2004. Also included in this report is a complete list of species known to have occurred in the area and their recorded abundance by week.

Conservation Issues

The Mendenhall Wetlands could be one of the most threatened Important Bird Areas in Alaska. It is surrounded by major urban development and immediately adjacent to an international airport. Also, immediately adjacent to the wetlands is Juneau?s largest sewage treatment plant, the city and borough?s landfill (which no longer burns garbage), and a large salmon aquaculture facility that discharges millions of pounds of ground-up salmon each year. Besides the direct threats that these facilities have on birds and their habitat a number of future plans and actions could diminish the value of these wetlands for birds. These include a second bridge crossing, airport expansion, and land acquisition of accreted lands by adjacent land owners.

Ownership

Most of the Mendenhall Wetlands are owned by the State of Alaska and are included in the 3,786 acre Mendenhall State Game Refuge. This refuge is managed by the Alaska Department of Fish and Game. A much smaller portion falls under the jurisdiction of the Juneau City and Borough ? this land is managed by the Juneau Airport. Another small portion is privately owned, this includes, the Smith-Honsinger Pond, an important area for waterfowl and other birds and the Juneau golf course.

Habitat

The Mendenhall Wetlands complex has the third greatest acreage of vegetated tidal salt marsh of all estuaries in Southeast Alaska. It is widely acknowledged to be one of the key migratory waterfowl and shorebird stopover locations of coastal Alaska.

The Mendenhall Wetlands includes all open, undeveloped land between the coniferous forest to the north, on the mainland, and the forest to the south, on Douglas Island. The east and west boundaries are the same as the Mendenhall Wetland State Game Refuge. Within these boundaries are small groves of spruce and supratidal meadows also known as uplift meadows. Plant diversity in these uplift meadows is high and important for mammalian grazers such as deer, bear, and porcupine. Sparrows and warblers nest in these meadows in fairly large numbers. Below the uplift meadow areas is the salt marsh.

This salt marsh includes a ?high marsh? ? dominated by several species of grasses ? and a ?low marsh? ? dominated locally by Lyngbye sedge. Below the sedge zone there are several different community types depending on substrate (finer muds or coarser sand and gravels) and exposure to tidal currents. In some cases sedges transition abruptly to mud flats. Elsewhere, a shorter ?lawn? of alkali grass, goosetongue, sea milkwort, and arrow-grass can be found.

A portion of the Mendenhall Wetlands is always covered by salt water. These areas especially provide forage for diving ducks and in the shallower areas forage for dabbling ducks.

Land Use

Since the Mendenhall Wetlands is located within the boundaries of a major Alaskan city (Juneau) it is used for a wide variety of activities. Most noteworthy are such activities as bird watching, research, education and hunting. Some of the land is destined for other uses but currently retains wetland characteristics that make it useful for birds.