by Bob Shanman
This is a story of four bird “cousins” (well, really, only two), who rarely, if ever cross paths. One summer in central Europe to Western Asia, and winters far to the south in Africa and southern Australia. One summer in the high arctic from western Alaska to Greenland, and winters as far south as the southern coasts of Chile and Argentina. One summer from central Alberta to South Dakota and winters along the Pacific, Atlantic, and Gulf coasts south into Central America. The last summers on the high arctic coasts of Russia and western Alaska. These birds winter on coasts as far south as the tip of Argentina and coasts of lands bordering the Indo-Pacific region. But one race in this group is very special.
The birds are the four godwits of the world (genus Limosa). The first is the Black-tailed Godwit, which has never been seen in California (the remaining three have). The second is the Hudsonian Godwit, on our coast. The third is the Marbled Godwit, a regular winter resident on our coast. The last is the Bar-tailed Godwit. It is the Alaskan population of this bird that is unique among migratory birds.
The godwits are large sandpipers, which are included in a larger group generically called shorebirds. The term sandpiper comes from the characteristic of the birds to rapidly probe (piping) into sand or mud to find food, typically small crustaceans, mollusks and worms along coastal shores. “Shorebirds” includes sandpipers, along with gulls and terns.
The godwit found on local South Bay beaches is the Marbled Godwit. There is little difference between male and female, although the females are somewhat larger with a longer bill (about 20% longer). During their winter visit, godwits are easily identified by their long, slightly upturned, two-toned bill. The base is pink, and the tip is black. Their feathers are mottled black and brown, and in flight, the underside of the wings is cinnamon. They can be in large flocks, or mixed in with other shorebirds, typically Willets. The only other sandpipers along the coast that are larger are the Whimbrel and Long-billed Curlew.
Marbled Godwits begin arriving on the local coasts in mid-August, stay through the winter, and begin their spring migration in late March to early April. Of the four godwits, their spring and fall migrations are the shortest. They breed primarily in the upper Midwest and southern Canada, a relatively short move of several thousand miles. They will stop along the way to rest and feed. Some non-breeding birds may stay at their wintering site all year. The first fall migrants are usually failed or non-breeding individuals, followed by successful breeders (one the young have fledged). Young birds are the last to leave and innately know where to fly for the winter.
Like most birds, Marbled Godwits are surprisingly light for their size. They are about 16-1/2 inches to 19 inches long, with a wingspan of 27 inches to 32 inches long, yet their weight is only 10 ounces to 16 ounces. Watch when they fly, and you will see that their wings are long and pointed, which is good for rapid flight but not so good for soaring or gliding.
The remaining three godwits are long-distance migrants. They all breed in high Arctic environments during the Northern Hemisphere summer, and then migrate to regions that are typically in the higher latitudes of the Southern Hemisphere. Most of these migrations are along coastal routes or over land, so there are opportunities to set down to rest and feed. Except for one race of the Bar-tailed Godwit.
The Bar-tailed Godwit is similar in general appearance to the Marbled Godwit. It has a long, slightly upturned, two-toned bill. In its winter plumage, it is paler than the Marbled Godwit, but much brighter in its summer, or breeding, plumage. It ranges in length from about 14-1/2 inches to 15-1/2 inches. But its wingspan ranges from about 36 inches to 44 inches. And breeding birds weighed in at about 22 ounces.
So why is this godwit special? It has a long migration. In fact, other birds, including the remaining two godwits, have longer migrations. But in the science of Ornithology, no other species has a migration like the Bar-tailed. Prior to 2007, it was known that Bar-tailed Godwits breeding in Alaska migrated to New Zealand. What was not known was how they did it. In 2007, researchers were able to implant a satellite tracking chip into one of the birds in the flock. What they learned was astounding. The flock migrated from their breeding grounds to the southeast coast of Alaska. There, they fattened up on the fat-rich foods along the coast. When the time was right, they took off on an epic journey. Over the next nine days, they made a non-stop, roughly 7000-mile journey to the north coast of New Zealand for the winter. Their spring migration took them to a food-rich estuary on the coast of the Yellow Sea in China. There, they again feasted, and made their last hop back to their breeding grounds in northern Alaska. Four legs, about 16,000 miles, and each leg was non-stop. The 7,000-mile leg is today considered the longest single non-stop flight by any of the over 11,000 species of birds in the world.
How do the birds do this? What fuels this flight? Remember, godwits are designed to fly fast and not glide or soar. What researchers now know is that birds making these incredible flights can shrink their internal organs (except the heart and lungs), and feed on fat-rich foods. They store the fats, and in some cases, will double their weight. This fat then becomes the fuel that provides the energy they need to make this journey.
And so ends the The Tail of Two (God) Wits. One is the bird seen on local beaches and marshes from August ‘til April and has the shortest migration of the four cousins. And one has the record for the greatest non-stop migration known to man by any bird in the world.
Bob Shanman recently retired, after 28 years as owner of Wild Birds Unlimited in the South Bay. He has been an avid birder since 1977. Information in this article comes primarily from “Birds of the World” [birdsoftheworld.org], a subscription/membership service of the Laboratory of Ornithology, Cornell University, unless noted otherwise.) ER
