The Great Backyard Bird Count is an annual four-day event that engages bird watchers of all ages in counting birds to create a real-time snapshot of where the birds are across the continent. Anyone can participate, from beginning bird watchers to experts. It takes as little as 15 minutes on one day, or you can count for as long as you like each day of the event. It's free, fun, and easy-and it helps the birds."

Personal tools

The Decline and Fall of the Rusty Blackbird

Help monitor this vulnerable species by reporting your sightings

By Russell Greenberg, director, Migratory Bird Center
Photo by GBBC participant Jack Bartholmai, Beaver Dam, Wisconsin

“Don’t it always seem to go, that you don’t know what you’ve got ‘til it’s gone….”

The well-known words from the pen of Joni Mitchell in her back-to-the-garden phase should be the watch words of all interested in bird conservation. The history of the North American avifauna is dotted with once abundant birds that declined, sometimes to extinction. Therefore, we must be vigilant for common species showing consistent decrease in abundance, and alarmed when we see what might be population crashes.

Rusty BlackbirdThe Rusty Blackbird is a case in point. Often taken for granted, the usual response these days when I ask birders if they have seen any Rusty Blackbirds lately is, “Come to think of it…no.” Most birders would probably be surprised to learn that prior to 1920, over half of the bird accounts for eastern North America listed the bird as very common to abundant. Only 7 percent list the species this way since 1950 and almost half of accounts from the same regions list the bird as rare to uncommon.

A long term decline like this is troubling. But the information from monitoring programs such as the Christmas Bird Count and the Breeding Bird Survey are downright scary. While the trend estimates are imprecise and have large error bars, the annual decline since the 1960s is consistently estimated at 85 to 95 percent. Such a large estimated decline in either data set alone would be alarming, and taken together they portray a species whose decline has accelerated to a free fall. In addition to the trend numbers, we have the experience of an increasing number of ornithologists working in the bird’s boreal breeding habitat, who are unable to locate the species in areas where it was formerly common.

It is particularly disturbing to monitor a decline and not have a specific, definitive underlying cause. But considering the distribution and ecology of this elusive species, the search for the culprit becomes almost like the Agatha Christie novel where all the suspects were guilty.

So this is what we know. The Rusty Blackbird has a geographically extensive breeding range from New England to Alaska throughout the boreal zone in forested wetlands. The species is strongly associated with wooded wetlands in the winter as well, although foraging birds can be found in agricultural settings, particularly in association with livestock. The species is more insectivorous than other blackbirds, often foraging in single species flocks, not associated with blackbirds, and (based on experiments by Claudia Mettke-Hofmann) is more averse to novelty when feeding than other blackbirds. The last observation suggests the bird may be less adaptable in the face of rapid environmental changes.

From this we can suggest a number of factors leading to the decline: Winter habitat loss due to conversion of wooded wetlands to agriculture. At least 80 percent of the bottomland hardwood habitat has been converted since European colonization. Habitat loss may have caused the Rusty Blackbird to feed in more open habitats where it is more exposed to competition with birds such as Common Grackles and Red-winged Blackbirds. Wintering ground problems could have been exacerbated by large losses during blackbird control programs in the 1960s and 1970s. It should be noted that the species is still listed as a pest species in a number of states and thus still subject to more modest control programs aimed at blackbirds.

Breeding habitat loss and degradation, including boreal wetland drying and changes in water chemistry due, directly or indirectly, to global warming. Birds associated with boreal wetlands have shown consistent cross-species declines. Global warming is suspected in causing major changes in the extent of boreal wetlands, the chemistry of the waters, and the structure of invertebrate communities. Peat production, logging and reservoir formation have contributed both to direct loss of boreal wetland and profound changes in hydrology, particularly in the eastern portion of the species range.

The eastern portion of the range is where, historically, the species may have achieved the highest breeding densities and is also the region where it has shown the greatest decline. Acid rain and mercury accumulation (an only recently detected problem in songbirds) may be differentially affecting boreal wetlands in the East. The Rusty Blackbird may be at higher risk for accumulated mercury than other blackbird species because of its preference for feeding on aquatic invertebrates and small fish. Its preference for wetlands with acidic soils may also make the effect of acid rain on calcium loss particularly great in this species.

With so many possibilities and so little hard information, it is clear that a vigorous and focused research program needs to be put in place. In February 2005, the International Rusty Blackbird Technical Working Group was founded to synergize and catalyze research and conservation on this troubled species. Already the group has initiated baseline research on breeding and winter ecology, isotope and genetic studies to connect populations between seasons, and population assays of methyl mercury accumulation in tissues. You can find out about the activities of Rusty Blackbird researchers and, more importantly, you can contribute to our knowledge by sending observations and (if you are a bander) contributing feathers and other tissues to be used in ongoing research. Read more about it here.

We also hope you’ll contribute your sightings of Rusty Blackbirds to the Great Backyard Bird Count. However you help, working together we hope to determine the cause and come up with management solutions before the species joins the growing ranks of the threatened and endangered.

To learn more about how to conserve boreal birds and their habitats visit the Boreal Songbird Initiative web site.