Laura Erickson's For the Birds

Friday, July 24, 2020

A Conversation with Don Kroodsma, Part 4: Connecticut Warbler

Connecticut Warbler


When I talked to Don Kroodsma last week, I told him about my pulling an all-nighter during the summer I was taking my first ornithology course, and about the robin who stayed up singing that entire night.  

Oh, my. If you’ve ever been out at midnight, one or two am, and the world is dead silent except for a singing bird, as it was with your all-nighter, it is one of the most memorable experiences you can have. I’ve been out with a number of night singers, just relishing them all alone on a silent stage. Oh, where should we start? Let’s go to the Connecticut Warbler
 
I was in a campground in northern Michigan and in the middle of the night, about 3 am, the mosquitoes were just driving me crazy—I was sleeping in the back of the pickup truck and I said, “I’m out of here. I’m just going to go where I planned on going a couple of hours later and walk around and listen.” Got out there and it was an hour and a half or two hours before sunrise, and two Connecticut Warblers were singing. And I thought, huh! That’s odd. Birds don’t routinely start singing during the dawn chorus until about 45 minutes before sunrise.  
 
Well, it wasn’t until a few years later that I got to test what I thought might be going on. And this is in your backyard, Laura, the Sax-Zim Bog. Got out there and the Connecticut Warblers—there were several birds on territory right along the road, and sure enough. These birds having just arrived from migration, presumably, were singing all night long. I sent you a graph of one of these birds. It was the night of May 29 and 30, 2016. And I started recording this bird nine hours before sunrise, which was a little before sunset, and recorded him till 9 hours after sunrise. And you look at this graph of 5300 songs that this male sings. 
 

It was about 10:00, maybe 11 o’clock at night, about an hour before sunrise and it was 6-7 songs per minute, like a metronome, all night long. And I just look at this graph and my jaw still drops. About 45 minutes before sunrise, there’s a little increased excitement to go along with all the excitement of all the other birds around him, but then he drops back down and he just sings consistently about 6 songs a minute until 2:20 in the afternoon and my batteries gave out and so I have only 18 hours of recordings for this bird, in which  he sings about 5300 songs all through the night. It was a stunning performance and one of his neighbors was doing the same thing, and the next night and the next night they were still at it. 
 
Don’s recording of this performance lasts over 16 minutes.  

I don’t think I include all 18 hours in the book, Laura, but it’d be tempting. You know, everyone should listen to 18 hours of Connecticut Warbler song. But in Recording #532, I simply extracted a bit of singing from around midnight. There’s probably a couple of spring peepers in there but on this very quiet night, except for a few frogs—anybody who’s ever heard a Connecticut Warbler, experienced it firsthand, knows how loud they are. They are just emphatic. And if you can imagine being a female Connecticut Warbler flying up there, they can hear what has to be an unpaired Connecticut Warbler male singing to attract her to his territory. And sounds carry enormously well at night, and you’ve heard of hot air balloonists being up in their balloon and they can hear people talking down on the ground like the ground serves as some kind of flat amplifier of sound that sends it directly up. 
 
So these males singing all night long had to be unpaired, singing all day long, too—that’s a characteristic of an unpaired singing male, just like the Brown Thrasher and so many other species that have been documented. So it’s gotta be their male strategy for Connecticut Warblers to sing through the night like this and then the question becomes, “Well, it seems like such an obvious strategy to sing in the night to attract an overflying female. Why don’t more species use it?” Well, some do, I guess, but it’s probably not during migration like a Northern Mockingbird—why, they’re resident. They don’t migrate, but an unpaired male will sing all night long or especially after midnight. So Connecticut Warblers. Oh—we could go on and talk about other warblers and why they’re so different from other warblers, but I’ll take a breath there.  
 
Don’s splendid book, Birdsong for the Curious Naturalist, is available just about everywhere. The accompanying website, birdsongforthecurious.com, is free for anyone who wants to listen to his Connecticut Warbler and 75 hours more of splendid birdsong. 

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