Laura Erickson's For the Birds

Tuesday, September 17, 2019

Where are the birds?

Black-capped Chickadee

Last week, I got a troubling email from Kate Salus, who lives about 7 miles north of Solon Springs Wi. She writes:
We have had chickadees forever here but they stopped coming for the summer totally. Usually we would see some during the summer but have not. It is September now and we still haven’t had any come to our feeders. I tried to search this problem but nothing. Are you experiencing a lack of chickadees????
Unfortunately, Kate, I’m not the right person to ask, because we’ve let most of our feeders go dry until our neighborhood rat problem gets solved. We do have a couple of hanging feeders which chickadees visit a few times a day, so they definitely haven’t disappeared from my neighborhood, but I can’t really comment about whether their numbers are above or below normal. I haven’t seen as many migrants as I usually do, but again, I’ve been busy with a book and so haven’t been focused out the window as much as normal, either.

But in the past week we’ve also had a string of emails on the Minnesota Ornithologists’ Union listserv about a dearth of birds that people seem to be noticing here and there. These accounts are about birds in general, not specifying chickadees one way or the other. And what’s happening in a given spot in a single year doesn’t give us any trends, but that doesn’t mean we should ignore the data points.

Chickadees disappeared suddenly and dramatically throughout a big swath of their range around 2002 when West Nile Virus hit. Some Christmas Bird Counts in Great Lakes areas back then found ZERO chickadees, or just one or two. Like crows and Blue Jays, chickadees are extremely vulnerable to the virus, with exceptionally high mortality. Little by little, they’ve “returned”—meaning the survivors have reproduced and chickadees from other areas have moved in to fill the void. 


In my own neighborhood, mosquitoes, which transmit West Nile Virus to birds and mammals, haven’t been much of an issue this year, but when I suggested the possibility of West Nile to Kate, she responded that where she is, “mosquitoes are always aplenty.” So that is one possible explanation. Now that most people have been exposed to West Nile Virus and have immunity, it isn’t the human health hazard that it was 15-20 years ago, and funding to get birds tested isn’t as easy as it was, but regardless, even when the disease was being thoroughly investigated and thousands of birds tested, chickadees were virtually never found dead anyway—they tend to retreat to their roosting cavities when they’re sick, so die entirely out of sight. If West Nile is the culprit, there should be some evidence in the form of disappearing Blue Jays, too, though that can be hard to assess in mid-September when they’re migrating, and jays from unaffected areas may suddenly appear en masse anywhere.

But as I noted, Minnesota birders are noticing a big decline in other species as well. And this is growing troubling in other places as well. Meanwhile, just this week a major study out of Canada, published in Science, reveals that birds are declining because of the same pesticide killing off bees. National Geographic reports:
The world's most widely used insecticide has been linked to the dramatic decline in songbirds in North America. A first ever study of birds in the wild found that a migrating songbird that ate the equivalent of one or two seeds treated with a neonicotinoid insecticide suffered immediate weight loss, forcing it to delay its journey. 
Although the birds recovered, the delay could severely harm their chances of surviving and reproducing, say the Canadian researchers whose study is published today in Science.  
“We show a clear link between neonicotinoid exposure at real-world levels and an impact on birds,” says lead author Margaret Eng, a post-doctoral fellow at the University of Saskatchewan Toxicology Center.   
Spring bird migration occurs when farmers are planting, and most crops in the United States and Canada are grown with neonicotinoid-treated seeds. Birds may suffer repeated exposure at successive stopover sites where they rest and feed. That may extend migration delays and their consequences, the study concludes.   
Neonicotinoids, introduced in the late 1980s, were supposed to be a safer alternative to previous insecticides. But study after study has found that they play a key role in insect decline, especially bees. 
Right around the time Neonicotinoids were introduced, the Reagan and Bush administrations were engaging in an active assault on environmental laws. One of the things I talked about on For the Birds way back then was how the Bush administration discontinued all field testing of pesticides before they could be registered. In retrospect, I wonder how much that was influenced by pesticide manufacturers knowing how dangerous neonicotinoids were? The EU banned the use of Neonicotinoids in 2018 because they were killing pollinators. 

Declining numbers of bees has horrible implications for both the natural environment and for agriculture here in the US and Canada, too. Now that we know these pesticides are also taking a big toll on birds, will we finally follow Europe’s lead? I won’t hold my breath. Meanwhile, I sure hope Kate’s chickadees return.

Black-capped Chickadee fledgling