Rigor Vitae: Life Unyielding

Sunday, January 09, 2011


While walking home yesterday, I noticed a dark, cylindrical form teetering on the sidewalk's edge. The fresh carcass of a European Starling (Sturnus vulgaris) was cool but still limp. Finding one of these common birds dead under its perch after a very cold night is hardly surprising, yet my thoughts turned immediately to Beebe, Arkansas and the dead blackbirds that we've all heard so much about. That was a surprising story that gave us all a new context through which to view something like this single unfortunate starling. It's only natural to make connections about such things, and connections we've been making. Newspapers reported a separate accident on January 3rd that befell another mixed flock of Red-winged Blackbirds in Louisiana, as well as what appears to have been around 100 dispersed, unrelated bird deaths in Kentucky. These were just the first of many to come. Accounts of the numbers and species have varied wildly. Reported bird deaths in Manitoba have ranged from 400 to “tens of thousands.” Dead corvids in Falköping, Sweden seem to number around 100. Add to this reports of fish die-offs--100,000 Freshwater Drums in the Arkansas River and 2 million fish of various species in the Chesapeake Bay--and you've got plenty of potential connections to make. I've been trying hard to make some of my own, but to no avail.

Most of these stories seem like the starling I found: mundane events that would normally merit little more than a shoulder shrug. The limited supply of reliable information makes it hard to piece together what caused these various deaths, but a common thread is hard to conjure. The Louisiana incident appears to have been a single accident that befell a flock of birds, as does another near Tyler, Texas. During the winter, blackbirds and many other bird species live at high density. In such a flock there's safety, but a disaster can take a staggering toll. Cold weather is deadly for birds as well, especially ones that aren't in the best of health to begin with. Only a small percentage of the birds that hatch each year survive to the next summer, and many, if not most of these deaths occur during winter cold snaps. I don't suspect that the dispersed Manitoba deaths fall outside of normal winter events. Like Tarzan said, “Life in jungle no bowl of cherries.” Cold weather, winter flocking and West Nile Virus seem a likely explanation for Sweden's dead Jackdaws. For now, I'm assuming that the phenomenon we're witnessing is not an ecological, but a psychological and social one.

That's also the line that Wildlife authorities are taking in articles like this one. They explain the cause of the Arkansas die-off as firework-shy birds panicking and flying into objects. Here, though, I think their confidence is overstated. Most birds, including blackbirds, employ a unique type of flapping, approaching a hover, when flying blind. Typically they will fly in circles, rising for a while before gently descending to a crash landing. The blind flight of a blackbird is nowhere near the 25 mph cited in the article. I wouldn't expect more than a handful of deaths from a thousand frightened, blindfolded blackbirds charging into a brick wall. Judging from the numerous accounts, the Beebe flock sustained losses of around 10%, maybe more. It's difficult for me to imagine this effect from a dozen fireworks, even if they all exploded in the middle of the flock. I used to work at Tracy Aviary, which is located in a park in the heart of Salt Lake City. For years, despite our annual protests, the city launched its 4th of July fireworks and the even bigger 24th of July fireworks right next to the aviary. The birds were subjected to around a half-hour long barrage, the entirety of which they spent smashing themselves against the walls and wires of their enclosures. Unlike the wild blackbirds, they were unable to escape the source of their anxiety, but losses were invariably below 1%, excluding broken and unincubated eggs and young birds that became hypothermic when their brooding parent left them. Birds in large flight cages that could potentially reach high speeds fared much better than birds in smaller enclosures, which were frequently battered, but rarely killed.

It seems likely to me that fireworks were what launched the Beebe birds from their roosts, but I think there must have been at least one secondary factor involved, although I can't offer any good suggestions. An updraft could have carried them high into a storm where rapid decompression, high-altitude hail, or perhaps just cold wet conditions did them in, or a strong crosswind could have increased their speed to the point that the wildlife management explanation becomes more credible—who knows? The Arkansas State Veterinarian stated that the birds his office necropsied showed no damage except for internal hemorrhaging. This was inferred as being caused by “blunt force trauma,” a phrase that has been picked up as the cause of death in most subsequent accounts.

Perhaps the Beebe deaths will forever remain a mystery, but for now I see no evidence of a single epidemiological, toxicological or any kind of logical factor that that has caused these deaths, or even that there have been an unusually high number of them in the past week. Nonetheless, as varied reports of mass Turtle Dove deaths in Italy flow in, I can't help but continue to try to draw those connecting lines.
illustration: WORKING THE FLOCK--MERLIN & STARLINGS (1988) acrylic 30" x 20"