Whidbey Island in September is only one tiny, micro-spot on the southbound bird migration map. Some shorebirds, swallows, warblers, even the diminutive Rufous Hummingbird fly right over us with hardly a downward glance.
Many other birds flutter down briefly to rest and feed, but their goal is to get back up into the flight pattern as quickly as possible and hasten on to warmer climes.
Migrating shorebirds — the long-distance champs — travel up to 7,000 miles between their summer breeding grounds in Alaska and northern Canada to their wintering grounds in southern United States, Mexico, Central and even South America. Some species fly at altitudes exceeding 10,000 feet and attain cruising speeds of 50 miles per hour.
Why do shorebirds travel into the high Arctic to nest, when they could stop well short of that destination? What is calling them? Or what are they trying to avoid?
Let’s consider three species of shorebirds that do stop to feed in our rich coastal lagoons such as Deer Lagoon, Crocket Lake and Swantown.
Recently, I watched a flock of 80 or so Western Sandpipers pattering around the mudflats of Deer Lagoon. This is the most common fall migrant along the Pacific Flyway. Six and a half million of these six- and a half-inch mottled brown, gray and white birds nest in a surprising small area of Yukon-Kuskokwim Delta in Alaska, above the 60th Parallel.
Still sporting some of their rusty brown summer plumage, the sandpipers plucked at prey with their dark, slightly down-turned beaks. The shadow of an eagle crossed the sand and they lifted in one sweeping motion into a softly peeping cloud. The shadow retreated and the tiny peeps settled back down to feed their travel-worn bodies.
The larger, 11-inch Black-bellied Plover tends to feed in a more solitary fashion. By the time they arrive here, their stunning black-and-white plumage has mostly molted into an over all grayish pattern.
My favorite fall migrating shorebird is the diminutive Red-necked Phalarope. Weighing in at only 1.2 ounces, it’s half the weight of a robin.
Unusual in the bird world, the female phalaropes are more brightly colored than the males, sporting a rusty red neck and chestnut colored marks along the dark gray back. After laying their eggs, the females depart and the males remain to incubate the eggs and raise the young alone.
I watch for these phalaropes in the water off the west side of Whidbey where they stop to feed. Behaving like avian spinning tops, the birds create an upwelling, which brings minute larvae, crustaceans and insects to the surface for easy plucking.
Ornithologists are still scratching their heads at the amazing migration feats of these three species and other shorebirds. They agree that the robust insect hatchings during the Arctic summer and the extended daylight hours at these high latitudes promote successful reproduction.
Yet the question remains: Is there enough benefit to balance the costs of a longer migration and the harshness of weather and exposure on high Arctic breeding sites? Why don’t the birds stop in the low Arctic zones where there is also plenty of food and daylight?
Recent research suggests that another reason shorebirds travel so far north is to avoid predation pressure, mainly from the key predator in these ecosystems, the Arctic fox.
In one study of a 3,350-kilometer south-north gradient in the Arctic, north of Hudson’s Bay, the risk of nest predation declined more than twofold at the northern sites. Scientists propose that this offers a substantial reproductive benefit, which more than balances the increased toll of traveling farther north.
As we learn more about the reasons why shorebirds select high Arctic breeding locations, it is important to keep in mind the danger and cost of their marathon migrations. We here on Whidbey must be vigilant to protect our local resting and feeding wetlands and tidelands that sustain them.
Those shorebirds are counting on us to keep the banquet open.
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