Spring is here, and one way to celebrate the returning season is to watch sandpipers along the Airport Dike Trail.
From mid-April through May flocks of migrating sandpipers stop to rest and feed on the Mendenhall Wetlands. Sometimes thousands of them arrive in a single day. Four of the larger species often forage close to the Dike Trail, so if you keep your eyes open you have a good chance of seeing greater yellowlegs, lesser yellowlegs, long-billed dowitchers and short-billed dowitchers.
Greater yellowlegs are the only species of the four that normally nest in Juneau (they generally nest on the ground in muskegs). The others are heading north, though in rare instances short-billed dowitchers have also been known to nest in Southeast.
All four species desperately need the respite and food they gather while on the wetlands. Many individual birds have flown thousands of miles to get this far. Most are neotropical migrants - they've spent the winter in Mexico, Central America or South America. Some may have wintered in the Lower 48 states. And some greater yellowlegs may have flown from as far as Tierra del Fuego at the southern tip of South America.
Along the Dike Trail the birds are attracted by ponds and muddy areas where their favorite foods are plentiful. Greater yellowlegs are the only sandpipers that regularly eat fish. You can often see them wading through shallow water, sweeping their bills back and forth, emerging with juvenile staghorn sculpins or other small fish between their tweezer-like mandibles. Dowitchers, on the other hand, use their long bills to probe into the mud, sometimes with the amazing rapidity of an avian sewing machine.
Juneau ecologists Mary Willson and Aaron Baldwin, who recently completed a survey of invertebrates on the Mendenhall Wetlands, found large quantities of small "macoma clams" and "corophiid amphipods" (tiny shrimplike crustaceans) in areas along the Dike Trail. Both these invertebrates are important foods for sandpipers. Also important to feeding birds are good visibility for protection against predators, the opportunity to feed in flocks, and the availability of resting sites nearby.
We've found five points along the trail where your chances are especially good for watching large sandpipers:
The mudflats adjacent to Mendenhall River, just off the end of the airport runway.
Fingers of the float plane basin pond.
Otter Pond, the big pond near the gazebo (probably the best spot in Juneau to watch greater yellowlegs fishing - and all from the comfort of the gazebo)
The next muddy area just beyond Otter Pond (nicknamed Junk Car Slough for the junk cars that used to line its banks).
Phalarope Slough, just off the Dike Trail, about halfway to the end (named because a Wilson's phalarope, rare in Alaska, has occasionally been sighted there).
Look for other sandpipers such as western or pectoral sandpipers in these areas as well, especially at high tide. By watching from the trail you will not only keep from disturbing the birds. you'll also get to share in one of spring's great spectacles, without even getting your feet muddy.
Bob Armstrong will lead a bird walk along the Mendenhall Wetlands airport dike trail beginning at 9 a.m. Saturday (May 8). For information on other spring walks see http://www.juneau-audubon-society.org
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