House Wrens are complicated, mysterious cheaters

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I got my start in ornithology studying the love lives of House Wrens. House Wrens pair up to raise their babies in a manner compellingly analogous to the human “nuclear family;” but, like most birds, both partners also often “cheat” on each other (i.e., copulate with other birds). This means that the male wren may have chicks in other nests besides his own, and he may end up caring for chicks that are not biologically related to him. (Note: edited. The original version of this sentence had a mistake.)

This sets up a number of interesting questions, such as: why cheat on your partner? Are the chicks sired by outside birds somehow better? Do males know when they are caring for chicks who aren’t their own? The answer to the latter question seems pretty clear (no, the males do not know), but the former two are more challenging.

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Last (?) junco field work

I was supposed to be done with field work after summer 2015, but you know how it is. The birds call. You realize that a few more blood samples would put the patterns you’re seeing in context in an illuminating way. You miss those feathery little dudes.

DSC_0169The small amount of field work I did this year took place much earlier than my usual field work because I was sampling juncos at a much lower elevation. Down here, the juncos are breeding in mid-March. Up at my usual sites, they wait until late May. That early start happened to be convenient for me, since I needed to analyze any data I got in time to file my dissertation in mid-May.

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Find the nest 5

This nest is a great example of juncos’ love of sloping ground. In some cases, like this one, the sloping ground is slope-y enough to call a wall. I wouldn’t call this a typical junco nest, but it’s not really surprising either: juncos are reliably creative with their nesting choices, which must make it difficult for predators to find them. This nest certainly seemed well-hidden—and it didn’t have to worry about being stepped on, either.

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Other nests

I’ve seen a lot of junco nests in my four years of field work. Rarely, I’ve been lucky enough to happen upon the nest of something other than a junco. I don’t find enough of these other nests to study them, so they don’t help me in my research—but boy, is it fun to find them!

Quick review: this is a junco nest.

_DSC7120This is not a junco nest:

_DSC6915Some major differences: the junco’s is a ground nest, while this one is a cup nest, suspended above the ground in the branches of a bush. The chicks are covered in light greyish fuzz instead of the junco chicks’ dark fuzz, and are maybe a bit stockier than the junco chicks.

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A predator caught in the act

We were searching for junco nests when I heard the unmistakable tic-tic-tic of junco alarm chipping. We followed the sound a ways and found a pair of juncos perched on a low branch, alarm chipping for all they were worth. Strange of the juncos to be alarm chipping at us when we were so far away, before, I thought. I wouldn’t have thought they’d see us as a threat from that far away. Odd birds. Directly below the branch with the agitated juncos was a small shrub. “The nest will be in there,” I predicted, showing off for my new field assistants.

2015_snake_nest2I parted the prickly branches, and tiny pink beaks gaped hungrily at me. “There they are,” I said, pleased with myself. “Three chicks.”

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And just as I said that, I saw the snake.

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Going out with a thud-crack-ow!

I just wrapped up what I think will be my last field work on the juncos for my dissertation. It was quite the eventful trip; I saw a few things I’ve never seen before – but more on that in a future post.

We were trying to catch an unbanded male. He was interested in our playback, but had escaped from the net once already, meaning he was likely to be wary of the net now. When he flew into the net the second time, I ran for him quickly, wanting to get to him before he managed to escape again.

…Or I started to run. Then I failed to clear a large rotting log and went down.

“Are you okay?” one of my field assistants asked.

“I’m not sure,” I answered honestly, from the ground. “Get the bird!”

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Find the nest 4

Juncos love to nest near corn lilies. Usually this means they nest near the base of the corn lily, using the thick stalk and broad leaves as cover. SEAL, however, decided that his nest didn’t need to be near an upright corn lily—and I have to admit that it’s not a bad idea: it took me an extra little while to find this nest, just because it didn’t look like a conventional junco nest location.

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