Tuesday, September 09, 2008

Swarms of Phalaropes

Half of our ABA group on the causeway leading to Antelope Island State Park, Utah.

Back in late June, during the American Birding Association annual convention in Utah, I was assigned to help lead a field trip to Antelope Island State Park. Antelope Island is located on the southeastern edge of the Great Salt Lake, north of Salt Lake City.

We left the Snowbird Lodge high in the Wasatch Mountains before dawn, dropping down to the desert along this large briny inland sea. Our trip consisted of two huge touring coaches, each one loaded with excited bird-heads.

Our first stop was along the causeway leading to the park entrance. So this is the Great Salt Lake. The smell of fermenting brine shrimp came onto the coach to meet us. Rugged plum-colored mountains surrounded the lake at a distance. Shallow brackish water bracketed the road. The water was so shallow that huge areas of salty sandflats appeared here and there, and the movement of birds and insects was obvious everywhere we looked. Stepping off of the bus I noticed several flocks of swift shorebirds flying overhead. They were buoyant fliers, snipelike in shape, but stiltlike in their gracefulness.

I was momentarily puzzled.

Then it hit me—just as someone else shouted "Wilson's phalaropes going overhead!"

Of course!
Wilson's phalaropes overhead, flying to join the huge feeding flocks on the Great Salt Lake.


Flock after flock, each one with between 12 and 30 birds, flew overhead, all headed in the same direction.

"Look at ALL those phalaropes!" I heard myself exclaim. I'd never seen so many at once.

"If you think that's a lot. Look out there, over the water!" said a birder next to me.

There, swirling over the water about 300 yards out were CLOUDS of phalaropes. They looked more like swarms of insects than flocks of birds. And they were reportedly ALL Wilson's phalaropes, staging, molting, and gorging before heading south for the winter.
Every June, as soon as they have finished nesting up north, the phalaropes begin gathering at the Great Salt Lake. As many as half a million may use the lake as a resting and feeding stop on their southward migration.

These birds, in a few weeks, would make a non-stop flight to northern South America. There they'll spend the winter on inland lakes high in the Argentinian Andes—a journey of more than 5,000 miles.

Red-necked phalaropes also pass through the Great Salt Lake, but not in such staggering numbers.

The appearance of these post-breeding phalaropes coincides with the large hatches of brine flies, small harmless insects that form their own dark clouds. The phalaropes and other birds gorge on the abundant brine flies, as well as the equally abundant brine shrimp, putting on body fat that will fuel their long migration.

Here it was, just the last week of June and already fall migration was on for these phalaropes.

I'll share a few images of the distant clouds of Wilson's phalaropes from our morning at Antelope Island State Park.

Like a wave above the water's surface, thousands of phalaropes shifted to new feeding spots.

The flocks were constantly ebbing and flowing.

This was just one small portion of the flock. It extended twice this far to each side of my camera's frame.


This must have been what flocks of passenger pigeons looked like 200 years ago.

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