After reading a newspaper article reporting that songbirds were dying in alarming numbers in the DC area, I started to notice dead and dying songbird fledglings in my Bethesda neighborhood — robins, jays, grackles, and starlings that had recently departed from the nest, but before they had attained their adult plumage. They suffered from eye and neurological pathologies. I spoke with Jim Monsma, the director of City Wildlife, in Washington, D.C., and he told me he was “deeply disturbed” by the magnitude of the event. His facility had been flooded with cases.
Of course, we all should be worried when we see our neighborhood birds dying in numbers. It is a signal that something is amiss. But what, exactly? A spate of articles and reports began appearing in the media, and it so happened that this was not just a local DC event, but was occurring in states from Kentucky and West Virginia to Indiana and Pennsylvania, involving the deaths of thousands of young songbirds. It brought to mind the West Nile Virus outbreak of 2002 that struck populations of crows and other songbirds in the U.S., killing millions of birds. That West Nile event also killed 284 humans as well as making thousands sick.
The late May timing of this songbird die-off seemed to align closely with the arrival of Brood X of the periodical cicadas that engulfed our DMV neighborhoods. During this mass emergence, it was commonplace to see birds feasting upon the hapless cicadas. Were the birds ingesting something from their cicada meals that was causing the sudden die-off? Might there be some Trojan horse pathogen lurking among the swarming cicadas, a new disease that might be transmitted to humans via foraging birds?
Tissue samples from the dead songbirds were sent for analysis to the USGS National Wildlife Health Center, the University of Georgia Southeastern Cooperative Wildlife Disease Study, the University of Pennsylvania Wildlife Futures Program, and the Indiana Disease Diagnostic Center. Moreover, a molecular analytical lab at the Smithsonian’s National Zoo & Conservation Biology Institute has been conducting follow-up studies to determine the plague’s source. An interagency statement released on June 9 reported that a variety of analyses looking for likely bacterial or viral causes of the die-off were unable to detect and identify the source pathogen. A lot of laboratory firepower has been targeted at identifying the cause of the songbird die-off and yet the result has been to delineate only what it is not (not West Nile, not avian influenza, not Salmonella, not Chlamydia, not Newcastle disease virus, etc.). Given the muscular state of our nation’s molecular analytical prowess these days, that is frustrating.
The die-off has now wound down. This is not surprising because the production of fledgling songbirds tends to finish by mid-July, when nesting season ends. But will the ugly phenomenon return next spring? In order to take stock of the current situation, I interviewed wildlife rehabilitators, molecular biologists, ornithologists and wildlife biologists. Here are some take-home points they offered up. The die-off killed mainly fledglings of a handful of common local songbirds. The optics were terrible, but the impact on these species was probably minor for several reasons. First, most fledgling songbirds do not survive their birth year. Second, the species affected are widespread and common, with ranges that extend well beyond the area where the die-off has taken place. There is no indication that any songbird populations have been decimated (something that did occur with the 2002 West Nile virus outbreak). Dr. Gary Graves, Curator of Birds at the Smithsonian’s National Museum of Natural History, posited that the most probable cause is a virus. Dr. Rob Fleischer, director of the National Zoo’s molecular lab agrees.
Here is the concern. COVID-19 apparently began as a mammal-borne coronavirus that jumped to humans. This sort of inter-species leap does not seem to have occurred with this outbreak as of yet but could in the future. We need the labs studying the phenomenon to find its cause ASAP. Only then will then be able to better protect ourselves (and our birds) from any long-term ramifications.
The most troubling aspect of this die-off is our inability to identify the cause. As with COVID, it could have been recently introduced from another environment. It reminds us that, as with COVID, there are many threats out in nature that remain beyond our proper understanding. And what we do not know can potentially harm us. It should give us pause, and make us more humble, and respectful of the dark complexities of wild nature — even those involving species that are our familiar neighbors.
And, of course, these very public deaths of young birds is heart-rending to all who care about wild creatures. The combined impacts of ongoing climate change, humankind’s massive alteration of the physical environment, and the myriad chemical toxins our societies unleash on the world at large render our birdlife and other wildlife vulnerable. This event should caution us to take pains to make our surroundings safe places for nature, in order to reduce the stresses that our neighborhood birds and other wildlife face. In doing so, we can shelter the wild species we treasure and make our own world greener and safer—not only for the birds, but for us as well. Let’s not forget the lesson of the canary in the coal mine.
Bruce Beehler is a local naturalist and author of 12 books, including “Natural Encounters” and “Birds of Maryland, Delaware, and the District of Columbia.”