Wednesday, July 16, 2008

A Handful of Rusties...

Russell Greenberg, head of the Smithsonian Migratory Bird Center at the National Zoo, recently wrote this interesting article on his studies of the Rusty Blackbird.

Greenberg's description of troops of Rusty Blackbirds "...diligently marching around the edges of leaf islands and wading the puddles, methodically searching the mud, flipping leaves, vigorously shaking wet green globs of vegetation in their bills, then pecking madly for any exposed invertebrates" instantly brought me back to one of the few times Warren and I have seen these elusive birds.

And, according to the USGS and Canadian Wildlife Service (CWS) statisticians, the reason we don't see many Rusties is that their numbers are decreasing rapidly: 12% per year.

A profound decline that "surpasses almost all other North American birds in the steepness of its descent"

What causes such a catastrophic decline in a bird that was so numerous 130 years ago that their flight would cause a dense black cloud?

Greenberg describes Rusty Blackbirds as "forest shorebirds", mucking about in shallow surface water beneath the forest canopy. During the winter, Rusties like bottomland hardwood forests and much of this habitat has been converted to agriculture or other uses or bound and controlled by levees.

There are also troubles on the Rusty Blackbirds' boreal breeding grounds. As subarctic temperatures increase, wetlands dry up and permafrost melts in boreal wetlands. These changes could impact the food chain that Rusties depend on to raise young.

Acid rain, mercury and other pollutants on breeding grounds may also be taking their toll on Rusty numbers.

Greenberg suggests habitat restoration of bottomland hardwoods and managing water levels in Rusty Blackbird preferred haunts would be useful first steps.

Continuing research is also necessary to understand the causes and ecological significance of the Rusty Backbirds' decline.

You can help the International Rusty Blackbird Technical Working Group with this research by submitting any migration or winter Rusty sightings here.

You can help the Rusty Blackbird and many other bottomland hardwood forest dwellers (possibly the Ivory Woodpecker) by supporting habitat conservation organizations such as Ducks Unlimited.

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