What happened to all the rusties?  I’m speaking of rusty blackbirds (Euphagus carolensis).  While no one was looking over the past 40 years, the entire population declined 85%-99% throughout North America.  That’s a catastrophic collapse.

I remember more than two decades ago how common they were in autumn and winter.  Oh, never in overly large groups mind you, but always in sufficient numbers to stand out from the crowd in the mixed flocks they inhabited.  And now?  Let’s just say I feel gifted to see three or four over the course of an entire season.

I don’t remember a winter during which I did not see a rusty blackbird, though I can say it once was easy to find them.  Now it takes patience and time.  Where once I could see a dozen or more with ease, today I have to look carefully to find the one or two hiding amongst various other species.

Rusty blackbirds often forage within flocks of starlings, cowbirds, grackles and other blackbirds—most notably around these parts within flocks of red-winged blackbirds (Agelaius phoeniceus) who share the rusties’ affinity for wetlands.  This perhaps explains how they slipped below the radar for so long and how their numbers dropped so abruptly in only four decades.

Well, that and the fact that they literally are black birds.  Like the many species of sparrow that leave most people happy to simply call a bird a sparrow, black birds cover a lot of territory: starlings, grackles, cowbirds, crows and ravens, and blackbirds.  How many would know which kind of bird they were looking at if they were looking at a black bird?  And assuming you could pin it down to a true blackbird, which of the handful of species is it?

Add to those complications two very simple facts: most people do not like or are ambivalent to black birds no matter what species they are, and black birds lack the pretty colors and patterns that most people look for when watching birds.  So they’re boring and they’re ignored, if not reviled, a double-whammy for the rusties.

It wasn’t until 2007 that the IUCN Red List changed rusty blackbirds from “least concern” to “vulnerable.”  The limited research and observation data indicate the population continues to decline; the decline has intensified over the past 10 years; and worst of all, no one has a clue as to the cause of the collapse or how to reverse it.  In other words, rusty blackbirds are teetering on the edge of extinction and got there so quickly and with so little notice that we’re scrambling to get our minds around the event before they’re all gone.

Unfortunately for the birds, it may already be too late.  As their numbers have dropped faster in the last ten years than they did in the 30 years prior to that, the cause and effect seem intent on beating any action we might take.  It would not surprise me to see them listed as endangered within the next year or two.  At the current rate they’re disappearing, that will be akin to closing the barn doors after the horses are gone.

[cross-posted to The Clade]