Not chasing Marsh Wrens

dsc_2711While I was working on my dissertation, I imagined that finishing it (finally!) would mean a sudden change in my life. I pictured an acceleration, a speeding-up of things: all the junco research published, a new research project started up efficiently thanks to everything I had learned from the juncos, new analyses performed and revealed quickly.

But although the junco research is on its way to publication, and although I am starting a new research project, neither process has been swift. I catch myself laying the blame for this at my own feet: why can’t I work faster? Why didn’t this get done yesterday?

I’ve been spending a lot of my free time in marshes lately. I like the combination of open space and dense impenetrability. I like the stalking egrets, the hovering kites, the harriers bounding along just above the reeds.

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“Rare” birds at the banding station

“Rare” is context-dependent. My Collins Bird Guide lists the Dark-eyed Junco as a “rare vagrant,” but that is, of course, because Collins is a bird guide to Europe. Common birds where you don’t expect to find them are exciting. We have our own rarities at the banding station, birds that may be common in the general region but rarely grace our nets; and although no one else would consider them remotely remarkable, we still get excited.

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Dark-eyed Junco

Juncos flock in huge numbers all around the area, but for whatever reason, they do not like the specific patch of riparian land that the banding station monitors. The banding station catches only around five juncos every year, making them rare by our very particular standards.

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Birds and mirrors, revisited

I wrote about birds and mirrors a while ago, and not much has changed scientifically since then. Most bird species tested have interpreted their own reflections as other individuals, responding either with aggression or courtship. Female pigeons who view their own reflections ovulate, apparently interpreting their reflections as suitable mates. Among birds, only magpies, so far, have been demonstrated to understand that the mirror reflects their own image, although pigeons can be trained to use spatial information from mirrors correctly in the real world.

So why bring this up again? Recently I saw a Yellow-rumped Warbler interacting with its reflection in a car side mirror, and took a video with my phone. Here it is (apologies for the lack of zoom):

At the time I took the video, I didn’t think much of it beyond general amusement. But rewatching it, I began to have some questions.

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Let’s not forget how cool dinosaurs probably looked

We know a little bit about how dinosaurs probably looked: we’re learning that a lot of them had feathers, and even beginning to be able to figure out what patterns might have been on their plumage. But there’s a lot we don’t know; we may never know for sure.

In evolutionary biology, when you don’t know something about an extinct species—what kind of nest it built, or what sounds it made, or how many babies it had—you look at the species that evolved from it. You infer that it probably was similar to at least some of its descendent lineages. For dinosaurs, then, we would look at birds.

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I remember, as a kid, thoughtfully coloring my dinosaur coloring books and paper-mache dinosaur scultures in shades of green and brown. I knew about camouflage, and I was sure that this earthy color palette must have been the one favored by these animals. Silly me.

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Birds looking odd? They may be molting

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This Chestnut-backed Chickadee is molting his head feathers, hence the odd colors.

After breeding, if you’re a bird, comes molting. Time to discard those old, worn, raggedy flight feathers and start with some fresh ones for the long haul of the fall molt, or replace sparse downy feathers with good warm ones for the cold of winter. This means that around now—from mid-July to September—you may see a lot of birds who aren’t looking their best.

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Finding the tiny dinosaurs in hummingbirds

Hummingbirds wear a public image of fragile, ethereal beauty: tiny jewels whirring through the air, occasionally pausing to drink daintily from a flower. Their unusual appearance supports this: the iridescent feathers, the long dainty bill, the near-invisible feet all make them seem quite apart from the everyday world of animals who don’t shimmer in the sun and do have feet.

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80% gemstone, 15% fairy from a storybook, only maybe 5% actual bird. He doesn’t even have feet! (Yes he does.)

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But hummingbirds, like all birds, evolved from dinosaurs. Hidden under that glimmering exterior is a tiny, fierce raptorial dinosaur.

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Baby season at the bird banding station

The birds are having babies, those babies are learning to fly, and they are flying into our nets at the banding station. They’re not really babies by this point: most of them are independent of their parents. They may have been out of the nest for a month or more, and are technically “juveniles” or “immatures.”

At the banding station we collect data on each bird we catch, including that bird’s age. It’s important to record the age if we can, because the more accurate we are with the age the first time we catch a bird, the more accurate we can be later. If we caught a bird in 2014 and recorded that it was a juvenile, then when we catch it in 2016, we’ll know it’s exactly 2 years old. If we didn’t bother to age it back in 2014, then in 2016 we would only know that it was at least 2. That maybe seems like a small distinction, but the lifespans of wild birds are still an area in which we lack a lot of information, so knowing exact ages is valuable.

How do you tell if a bird is a juvenile or an adult? In some species, the juveniles are dramatically different colors than the adults. Juvenile juncos, brown and streaky, look distinct from adults even from a distance—until they molt, at least. But the differences can be a lot more subtle.

Here is a Common Yellowthroat from the banding station:

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How old is it?

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