Nature up close: Shorebirds

By “Sunday Morning” contributing videographer Judy Lehmberg.

“Sandpiper” is a term much like “sea gull” -- both generic terms applied to a group of birds. There are actually more than 55 species of gulls. Although sandpiper is a bird species, it is often used to apply to a group of birds more correctly known as shorebirds. There are at least 90 species of shorebirds, with more than 60 in North America. Sanderlings, the subject of this week’s Moment in Nature, are quite common along all North and South American coasts. In fact, they are one of the world’s most widespread shorebirds. 

Sandpipers have one of the longest migrations of any bird. Not the longest -- that prize goes to the Arctic tern who, for reasons unknown to us, travels from its breeding grounds in the Arctic to Antarctica and back again every year. That is a round trip of more than 44,000 miles (because they don’t travel in a straight line). And because they can live more than 30 years, that could add up to 1,500,000 traveled miles in a lifetime. We would be thrilled to get 1,000,000 miles on a car. [My husband got nearly 700,000 on a Volkswagen van, but that included three different engines, two of which weren’t even Volkswagen, and he still brags about it.]

Many shorebirds have long migrations. Sanderlings breed in the Arctic, but winter in Chile or Peru after crossing North America from West to East and then traveling down the Atlantic coast. In the spring they return to the Arctic by way of western North America. That is a round trip of about 18,000 miles. The pectoral sandpiper travels from its nesting grounds on the tundra in northeast Asia, Alaska, and central Canada, all the way down to wintering grounds in South America, with some of the Asian breeders going as far as Australia and New Zealand. That is also a round trip of around 18,000 miles.

How do we know they travel so far?  Transmitters have now gotten tiny enough to put on a small bird and then tracked by satellites. We now know some shorebirds can cover almost 2,000 miles in less than two days. So far the longest nonstop flight for any bird ever recorded was of a bar-tailed godwit. One bird flew from Alaska’s west coast to New Zealand in nine days, covering 7,145 miles without ever touching the ground, eating or drinking. There is no airplane that can boast of such a record. They do sleep but it is not the type of sleep we know; they “sleep” by shutting down one half of their brain at a time.  

Bar-tailed godwits routinely fly over the Pacific Ocean to winter in New Zealand and then return to the Arctic to breed every year. In late July Alaskan bar-tailed godwits gather on the Alaska Peninsula to feast on small clams.  By the time they are ready to fly south about 55% of their total body mass is fat, and their kidneys, intestines, and liver have atrophied. They then wait for a favorable wind and take off into the unknown Pacific. Many of those birds are only a couple of months old and do not depend on adult birds to show them the way. The route appears to be genetically ingrained. Ten or so days later the lucky ones arrive in New Zealand weighting about one half what they did when they last touched ground.

One of the reasons bar-tailed godwits can accomplish this amazing flight is that the Alaska Peninsula, including the Copper River Delta, provides a huge amount of food. Scientists are beginning to realize how much shorebirds rely on a small number of such locations where food is amazingly abundant. Just five of those are in North America: Alaska’s Copper River Delta; Washington’s Gray’s Harbor; Delaware Bay in Delaware and New Jersey; Canada’s Bay of Fundy; and Kansas’ Cheyenne Bottoms.

Over 80 percent of the 20 million shorebirds that migrate through the U.S. depend on these five sites, some of which have been threatened with coastal and wetland development, forcing the shorebirds into dwindling habitat. Efforts from the combined work of the World Wildlife Fund, the National Audubon Society, and the Association of Fish and Wildlife Agencies are attempting to save these areas, but their success hinges on the assistance of local, regional and national governments. The governors of New Jersey and Delaware have already mandated the Delaware Bay estuary as a shorebird reserve.

If you would like to learn more about bird migration, I highly recommend “Living on the Wind: Across the Hemisphere with Migratory Birds” by Scott Weidensaul.

Judy Lehmberg is a former college biology teacher who now shoots nature videos.

       
For more info:

• Judy Lehmberg (Official site)
• Judy Lehmberg’s YouTube Channel

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