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Sunday, August 18, 2013

Fall Migration Gets Underway at Lake St. Clair

[Aug 2013. Lake St. Clair Metropark, MI]

The shores of Lake St. Clair provide a welcome respite to migrating sandpipers, plovers and other species on their way South to warmer climes. A mid-August excursion to this busy Metropark yielded 4 species of sandpipers and 2 of plovers.

First Semipalmated Sandpiper -- a tiny sandpiper with black legs and bill, this species is an abundant shorebird with a global population of 3.5 million. Breeding in the Tundra, it is a passage migrant through North America with massive flocks gathering in the Bay of Fundy and other favored areas.

Semiplalmated Sandpiper

Disambiguation with Least Sandpiper is usually possible without much trouble -- Leasts generally show more brown in their plumage; and, critically, have yellowish legs.

Semipalmated is very similar to Western Sandpiper especially in basic plumage; it also shares partially webbed feet and black legs. However, Western's bill is longer and more drooping. The half-webbed ("semipalmated") feature, therefore, is not diagnostic and generally not observable.

The migration range of Semipalmated and Western are disjoint -- the former down the Eastern half of the US and the latter, aptly, down the Western half of the country. However, in winter, peeps observed on the Southeast and Gulf coasts are also Western Sandpipers. For decades, they were being misidentified as Semipalmateds!

Just slightly smaller than Lesser Yellowlegs, the next sandpiper, is a medium sized calidrid  -- found as a breeder in North America as well as Northeast Asia. Strictly a passage migrant in the US, this species winters in South America and Australia.

Pectoral Sandpiper

While still fairly common, the current population is estimated to be less than 100,000 -- probably less than a tenth of what it was before market hunting decimated their populations (other sandpipers, notably, the Eskimo Curlew, were less fortunate).

The Pectoral Sandpiper is a "grasspiper" and feeds by sight;  not by probing. They are extremely long distance migrants -- known to travel up to 10,000 miles to their wintering grounds.

Least or Semipalmated?

The above sandpiper shows dull greenish legs; could this be a Least?

Least Sandpiper

Least Sandpiper shows yellowish legs and a short, fine bill. Compare the feet in the above two photographs -- the first photograph shows partial webbing which is absent in the 2nd image. Indeed, the first image is that of a Semipalmated Sandpiper whose black legs are covered in green slime (algae and mud); thus, highlighting the perils of reliance on leg color alone as a definitive diagnostic aid.

The rich brown in the plumage at this time of year of the Least Sandpiper is striking.

Least Sandpiper

 Aptly named, this is our smallest peep.

Unlike Pectoral, Leasts winter widely in the US and can be commonly found in suitable habitat.

The last of our 4 sandpipers, shown above, is the Spotted. Spotted Sandpiper is both a breeder and a migrant at Lake St. Clair.

Also observed was a stunning Black-bellied Plover in full breeding plumage.

Since they are generally encountered when they are in their basic plumage, they are known outside of the US as the "Grey Plover" (which aptly describes their winter look).

Black-bellied Plover

In the picture above, the Black-bellied is seen with another plover -- Killdeer. The latter act as sentries for the other shorebirds.

Other birds observed included the imposing Caspian Tern -- much like the fact that the Black-bellied is our largest plover, the Caspian is our largest Tern.

On the Heron front, a Great Egret was seen at the shore while a Green Heron was observed at one of the marsh ponds.

Great Egret

Green Heron

Finally, some songbirds:

An American Goldfinch and a Northern Cardinal -- never failing to brighten up the day.

A half-dozen species of shorebirds augurs well for a Fall migration that is gaining steam as shorebird momentum builds and species diversity increases. And, despite the occasional off-leash dogs, marauding beach goers, and throngs of ill-behaved juveniles, Lake St. Clair is still a choice location for observing the magic of migration.

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