Posts Tagged ‘questions’

Medium-Sized Mysteries

April 7th, 2011 | Meera

I continue to spend Thursdays in the prep lab. While I’m there each bird represents a small, self-contained mystery. What species is it, and is it new to me? Where did this particular individual come from—the collision monitors, a rehabilitation center, a museum security guard who saw something on the path outside and brought it in? How did it die? Was it healthy and well-fed on its last day? Was it young or old? I can answer most of these questions as I go along, using the bird’s outer (and inner) appearance and the information on its tag.

I also like to think about the bigger mysteries the Field’s specimen collection is designed to help researchers answer. How do bird populations change over time? Which ones are increasing, and which decreasing? Are migration routes and timings affected by global warming? Can we see evolution at work in the shape of a wing, or a bill, or a foot, if we go back far enough?

Sometimes, though, I get a glimpse of medium-sized mysteries: curious, spontaneous questions raised by the specimens themselves.

I.

In late September 2009, on a stormy night in Minnesota, hundreds of birds from a wide variety of species flew into a tall structure—a telephone tower or something like it—and were killed. The dead made their way, via the Minnesota Department of Natural Resources, to the museum. And eventually, after a long rest in the freezers (we’re behind on specimen preparation), Dave began taking them out for processing. When that happened, he noticed a strange thing. If birds of those particular species had been found at that time of the year in the Loop, the vast majority of them would have been juveniles. But the Minnesota birds were almost all adults, with fully ossified skulls and well-developed gonads. This held true over the entire range of birds (which include sparrows, warblers, thrushes, grosbeaks, and ovenbirds, just going by what I’ve personally prepared).

Why would this be the case? Dave says that for now, he truly has no idea. So he’s working on collecting data about the entire group of specimens, and while he’s doing so he’s talking to his colleagues and trying to formulate theories that could explain this strange occurrence. Eventually, they’ll either come up with a brilliant explanation, write a paper about it, and let everyone in the community know, or they’ll remain stumped, write a paper about it, and invite everyone in the community to help figure it out. It seems like a pretty wonderful process: an example of the way science is supposed to work.

bay-breasted warbler
(This is a bay-breasted warbler from the Minnesota tower kill.)

II.

At some point in the day today I was looking for the box of yellow pins we use to fix study skins to the foam boards on which they dry, and it turned out Dave had spirited them over to the sink. When I got there I discovered that he was sitting in front of a giant tray of American woodcock carcasses, opening them up, and—if they were female—pulling out their ovaries and oviducts with a pair of tweezers and pinning them to little pieces of cardboard. Then he was putting them into a jar of formalin.

Why would he do such a thing? Well, it’s like this. The museum has a large number of woodcock specimens, collected as they pass through the area during fall migration. At some point Dave noticed that a lot of the female woodcocks had very large and well-developed sexual organs—a characteristic typically associated with the height of mating season. A few of them actually had eggs that were at the yolking stage. I saw one that was clearly yellow and as big as a large marble! Maybe, he thought, the birds were mating as they migrated. (An unusual behavior, worthy of study.) Also, he had a vague memory of someone, not a full time museum staff member but a scientist who’d passed through the lab, having been interested in a question like this—years ago.

So Dave decided to preserve the ovaries and oviducts of all the female woodcocks in the division’s freezers, against the event that that person—or someone like them—would eventually want to check the organs for sperm. He only regretted that he didn’t have the time or space to put them in liquid nitrogen so that the DNA they contained would be preserved. This would allow the future hypothetical researcher to also ID the sperm and find out if the females were mating with different males on different nights of their migration route. As it was, pinning out the ovaries took him hours (and was absolutely fascinating to watch). I made him let me take a picture.

american woodcock ovaries-oviducts, pinned for preservation

Medium-sized mysteries: maybe their answers will be of great scientific import; maybe they won’t. But it’s fascinating to see them appear without anyone even looking for them, like bits of flotsam washing up on the shore.