I recently helped complete a study of bird use of the Mendenhall Wetlands. The primary objective of this study was to determine areas on the wetlands of special importance to birds. Another objective was to determine what attracted birds to these areas.
The report of this study recommends enforcement of the Juneau dog leash law along the dike trail and state law governing harassment of wildlife on and near the refuge. These recommendations were made because during surveys we frequently noted birds - especially ducks, geese and sandpipers - being displaced by uncontrolled dogs. This was very common along the dike trail within the various sloughs and ponds that border the trail. We also occasionally observed loose dogs chasing birds throughout the refuge, sometimes at considerable distances from their owner.
Several of the sites along the dike trail are important feeding areas for sandpipers and waterfowl. A report on invertebrate surveys on the Mendenhall Wetlands helps us to understand why birds feed in these areas. In the sloughs closest to the dike trail they found tube-dwelling corophiid amphipods and juvenile macoma clams to be abundant. These amphipod and clam species are among the most sought-after and important food of sandpipers. In the floatplane basin and the adjacent sloughs, ditch grass attracts geese and other waterfowl. Ditch grass is not nearly as abundant elsewhere on the wetlands. And preliminary analysis indicates that tube-dwelling amphipods may also be less abundant elsewhere. Hence, sandpipers, ducks and geese are attracted to the vicinity of the dike trail for feeding on food they may not be able to obtain in similar abundance elsewhere on the wetlands.
The Alaska Shorebird Conservation Plan recognizes three important shorebird sites in Southeast Alaska - Stikine River Delta, Yakutat Forelands and Mendenhall Wetlands. Seventeen species of shorebirds are listed in this plan as having a statistically significant decline in overall numbers. All but one of these species of shorebirds stops to feed on the Mendenhall Wetlands. Also, the Mendenhall Wetlands is second only to the Stikine Delta as having the greatest amount of salt-marsh vegetation in Southeast - important food for geese and other waterfowl. Hence, the Mendenhall Wetlands is extremely important to birds migrating through Southeast Alaska to their more northerly breeding grounds. Sandpipers often occur on the wetlands in substantial numbers - up to 5,000 western sandpipers have been counted in a single day. Radio tracking of these birds indicates that they spend only a day or two at their stopover sites. During the stopover, best foraging conditions are often available only for a few hours around low tide. For a small bird on a journey of thousands of miles between wintering and breeding ranges, efficiency of refueling and quality of resting time can mean the difference between life and death, or between success or failure at reproduction.
Studies of shorebird response to various kinds of human activities have found that dogs caused the most serious disturbances. These studies are mentioned and discussed in our report.
Displacement of birds by dogs can cause birds considerable stress and loss of feeding opportunities. I encourage dog owners to control their dogs on the dike trail and elsewhere on the wetlands. This will be especially important during the shorebird migration in April and May and again in July and August.
Copies of the report titled "Hotspots: Bird Survey of Mendenhall Wetlands April 2002 to May 2003," and the report on "Invertebrate Surveys on the Mendenhall Wetlands," are available at the Juneau Public Libraries.
Bob Armstrong is a retired biologist from the Alaska Department of Fish and Game and has taught Ornithology and Biology of the Mendenhall Wetlands at the University of Alaska Southeast.
© 2016. All Rights Reserved. | Contact Us