The Rarest of Blackbirds

On a recent Monday morning that was so snowy that school was canceled and the county roads were undisturbed by any moving vehicles, I went outside to fill the feeders. Moments after returning to the warm indoors I noticed a number of dark birds foraging on the ground, inside the brush pile. Wiping my still-foggy glasses, I could see that they were not common grackles.

The fact that they were foraging inside the brush pile made them very interesting. Grackles and red-winged blackbirds, both regular species at our feeders, usually forage on more open ground. Binocs to the eyes—rusty blackbirds!

This foraging behavior made perfect sense! This is a species that breeds in swampy woods in the far North. It's perfectly at home in dense habitat—especially when there is some cracked corn there to gobble up.

A few identification clues for the rusty versus other blackbirds:

• the rusty plumage is a great clue in fall and winter. Similar Brewer's blackbird females in fall show gray, not rust in plumage.
  
• pale eye stands out on the dark face around the eye.
• Pale rusty eyeline is obvious in fall females. Red-winged blackbird females are streaky overall.
  
• smaller overall than a common grackle.
  
• tail and bill shorter than common grackle.
• Prefers wooded, swampy habitat.
  

The rusty flock had five birds in it, and so I snapped a few digiscoped shots and a bit of video to document their presence. I'm sure the winter storm of Sunday brought these birds southward. Sadly, when we see rusty blackbirds at our feeders, they rarely stick around. This morning (Tuesday) we had just one rusty foraging under the pines on the western edge of our yard.

From these photos you can see how the species got its name, from the rusty edges on the bird's newly molted-in fall plumage. This is interesting since adult males in breeding plumage show no rust in their glossy blue-black finery. Fall males have dark bodies scalloped with rusty feathers. These three photos in this post show an adult female in fall (non-breeding) plumage.

The rusty blackbird has been experiencing a serious population crash in recent decades—some estimates say the population has dropped by 90 percent! Why? We're trying to find that out.

One thing seems certain: this species is a habitat specialist. It prefers wet wooded habitat and this habitat type has been greatly reduced in North America in the last century due to logging, draining of swamps for agricultural uses, suburban sprawl, and mosquito control measures. But habitat loss along may not be the whole reason.

Scientists suspect that the rusty blackbird's decline may also be tied to changes in food abundance in the swampy/boggy northern woods where the rusty breeds. It forages along the edges of the water, catching and eating lots of water-borne creatures such as salamanders, snails, insect larvae, and small fish. Acid rain and rising levels of mercury from air pollution have had a detrimental effect on this prey base.

Additionally, rusty blackbirds are getting hammered on their wintering grounds. In winter they sometimes join huge blackbird flocks in the South, along the Gulf of Mexico. These blackbird flocks are persecuted as agricultural pests—sometimes dying in the thousands after being sprayed with toxic chemicals from crop-dusting airplanes.

In 2005, the Smithsonian Migratory Bird Center formed The Rusty Blackbird Technical Working Group to study this species and its shocking population decline. Last year they held their inaugural Rusty Blackbird Blitz to document the species' presence throughout its winter range. Dates for the 2011 Blitz are January 29 to February 13, 2011. A state-by-state list of Blitz coordinators is available online. Data collection is being handled by eBird, the joint effort by the Cornell Lab of Ornithology and Audubon. All birders in the rusty blackbird's winter range are invited to participate.

In case you've never seen a live rusty blackbird, here's a short video for you to ogle.