Wild About Wood Thrush

We are very excited to welcome Kit Straley, a PhD Candidate from the University of Massachusetts in Amherst to the blog today. For more about Kit, see the end of this post.

Have you ever found a bird’s nest? Perhaps you found a robin nesting on the top of your gutters, or a cardinal in your bushes. One time I accidentally found a mallard duck nest in one of the landscaped dividers of a Wegman’s parking lot. What was your reaction? Before starting my PhD project on nesting wood thrush, finding a nest was just a nice surprise in my day. Now, from the months of May-August, the process of nest searching, finding, and monitoring literally takes over my life. And I love it.

For my typical day in the field, I wake up around 4 am to a cacophony of birdcalls outside my window. This is a great first sign for the day; the weather must be good for birds to be advertising their territories with their song. Why so early? Later in the day the birds quiet down, and it is much harder to find their nests.

I grab my equipment – binoculars, a field journal, a compass, a GPS unit, and a small telescoping mirror. I’m off to my study sites – forest fragments in suburban Massachusetts and a continuous forest surrounding a reservoir.

Snap shot of my study site at the Quabbin Reservoir in Belchertown, MA. Wood thrushes nest in the forested areas. 

I hike into the woods and listen for that characteristic wood thrush “ee-oo—lay!” I hear one far off on my left. When I first learned their song, I thought that calls at this volume meant they were maybe 100 feet away. Ha! Wood thrush songs ring out across the forest canopy, and sometimes I can hear individuals over 400 feet away. I look to my left and of course I’m going off trail.

Rule #1 for nest searching: Birds don’t care about convenience for you i.e. trails.

I step out into a field of ferns, punctuated with white pine saplings. The hip-height ferns are really good at hiding logs, so as I track the bird I watch my feet. I have face-planted many times in the pursuit of nests. I follow the direction of the song, crashing through prickly barberry patches and slugging across a skunk cabbage swamp. I look up into a nearby tree. He should be right there! I can hear him right there! I focus my binoculars and spend 20 minutes looking for my serenader. Eventually, I take a single step to the left. He’s been there the whole time, just barely blocked out of sight by a branch. Tricky fella.

Now here’s the thing about wood thrush males. They have a pretty big to do list: they sing to defend territories and attract mates, feed themselves, feed their young, and even bring food to females sitting on the nest. They don’t, however, incubate eggs or sit on top of the young to keep them warm. Ultimately, they don’t spend a ton of time right on top of the nest. Even if I find a singing male, that doesn’t mean I have any clue where his nest is unless he visits it while I’m there. As I’ve already established, our current subject is a tricky one. I watched this male for over an hour without him moving more than 10 feet from his original perch.

A rare sighting of a wood thrush male on the nest. He will generally wait for the female to return before flying away. 

If the male’s behavior doesn’t lead me to the nest, and I can’t find the female because she is most likely hunkered down incubating the eggs, then how do I find the nest?

Step 1-Get incredibly irritated that I just spent an hour watching the male and he didn’t even have the decency to lead me anywhere close.

Step 2- Start moving around to see how the male reacts. Does he watch me closely? Does he start to go “bup-bup-bup” and “wick-wick-wick” at me? And the holy grail of nest defense – does he hurtle towards me and veer up in the last second so close to me that I can hear the wind through his wings? If so, I can bet I’m near the nest. If not, I proceed to…

Step 3 – Start searching based on habitat cues. I know I’m near his territory. I know that wood thrush in my study like to nest in white pines or blueberry bushes, anywhere from 3-15 feet high. I start scanning the vegetation for any suspicious looking clusters of sticks and leaves. As my lab mate once told me, for every 75 leaf bundles you look at, 1 will be a nest.

From a distance, nests can look like leaf bundles. The freshly built nest on the right was used this past season. The drooping nest on the left may be leftover from last year.

I systematically hike around the area. On quiet days when the males aren’t singing, I have to skip Steps 1 and 2 and search on habitat cues alone. Those days are long and tough. After over an hour of nest searching for this tricky fella’s nest, I just need to give up. There are other territories to be explored, other study sites to be searched.

Rule #2 for nest searching: Never walk back to the trail the exact way you came. Did you find a nest on the way in? No. So why would you find one walking that path on the way back?

I turn a corner around a large maple tree and BAM. I am face-to-face, beak-to-nose with a female wood thrush. She sits regally on her nest, approximately 10 feet away from me. Oh sh*t! I think. I found your nest! And she is looking at me with a face that says Oh sh*t!—You found my nest! She is completely still with her body pressed as far into the nest cup as she can get.

A wood thrush female sitting tight in her nest. Her tail is sticking out the back! Photo by James Smith. 

I slowly approach the nest, careful not to trample any of the plants so I don’t give the nest location away to predators. I take my small telescopic mirror and lift it to the nest cup, gently persuading the female to fly off. With an aggressive bill CLACK she flies away and perches to watch me. I put up the mirror and count 1, 2, 3, 4! Four beautifully teal round eggs. I back off, and as I go I quickly take a GPS point, estimate the height of the nest and the plant that the nest is in. These actions take less than 2 minutes, but it feels like forever as my adrenaline is pumping.

What I’m likely to see during a nest check using my mirror – a teal egg and three freshly hatched young. Photo by James Smith. 

Nothing beats the rush of finding a new nest. The process can take hours and sometimes I spend a whole day searching with nothing to show for it. This past season I went a whole 3 weeks without a new nest – I thought I was cursed! Given how much time nest searching takes, how many miles of off-trail hiking I do without the guarantee of any results, and how many bug bites and ticks I get for my effort, why do I love nests?

A female sitting on the nest to keep chicks warm. They are so big at this point that she cannot fully sit in the nest! Photo by James Smith. 

 

New nests mean more data. Over the course of the next 2 weeks I will check on the nest to make sure the eggs or chicks haven’t been eaten, place a nest camera to record parental behaviors, and even carefully borrow the chicks to measure their bodies and see how they’re doing. I gently tuck the borrowed chicks back into the nest and wait to see when they will fledge on camera.

Three “borrowed” chicks waiting to be measured for their weight and the lengths of their wings and legs. The two on the right are gaping, begging for food. 

It’s an incredibly rewarding experience to watch them grow between each nest check, to see the parents bring in food to gaping beaks, and ultimately to watch them hop out of the nest and stretch their brand new wings. By studying the nesting success of wood thrushes in suburban forests in comparison to larger forest stretches, I can highlight the importance of smaller forest patches for the preservation of these amazing birds.

A chick fledges from the nest, conveniently jumping down right in the direction of the nest camera, wings spread. In the nest you can see the small bulge of its sibling watching. 

Kit Straley is a PhD Candidate in Organismic and Evolutionary Biology (OEB) at the University of Massachusetts in Amherst. She is a self proclaimed bird nerd and admittedly loves the grueling hours of her field seasons because she gets to spend her time outdoors with birds. Prior to working on avian urban ecology studies, she completed an internship on nesting sea turtles and performed research on the behavior of small mammals.