5.24.2010

Migrating birds on the front page of the NY Times

I'm very impressed and surprised by the coverage. And its a great story about innovations in scientific research. I didn't even realize that when I was a kid watching wildlife videos and learning about the Arctic tern that we couldn't actually observe them migrate. We could only see where they started and ended. But now with smarter tracking technology, we can observe their entire trajectory.

The whole story reminds me of other innovations in observational technology that slingshotted an entire field. For example, the invention of GFP, which can make portions of tissue glow, lead to enormous advances biology and related fields. (Martin Chalfie, one of the inventors who won the Nobel for it, is here at Columbia. I know because I saw him explain the idea to a gymnasium full of kids here with a [humorously] malfunctioning flash-light). I think that a lot of times, when we learn science in [grad]school, there is so much focus on theory, mechanisms and methods that we sometimes forget that the starting point of all science is observation.

PS. If you're like me and did a double take at the article's nonchalant statement about the groundbreaking technology
Geolocators ... just record changing light levels. If scientists can recapture birds carrying geolocators, they can retrieve the data from the devices and use sophisticated computer programs to figure out the location of the birds based on the rising and setting of the sun.
You should check out the website of the geolocator manufacturer Lotek, where they post scientific papers on the method. Here's an abstract from "An advance in geolocation by light" by P. A. Ekstrom (2004):
A new analysis of twilight predicts that for observations made in narrow-band blue light, the shape of the light curve (irradiance vs. sun elevation angle) between +3 and -5.DEG. (87 to 95.DEG. zenith angle) has a particular rigid shape not significantly affected by cloudiness, horizon details, atmospheric refraction or atmospheric dust loading. This shape is distinctive, can be located reliably in measured data, and provides a firm theoretical basis for animal geolocation by template-fitting to irradiance data. The resulting approach matches a theoretical model of the irradiance vs. time-of-day to the relevant portion of a given day's data, adjusting parameters for latitude, longitude, and cloudiness. In favorable cases, there is only one parameter choice that will fit well, and that choice becomes the position estimate. The entire process can proceed automatically in a tag. Theoretical estimates predict good accuracy over most of the year and most of the earth, with difficulties just on the winter side of equinox and near the equator. Polar regions are favorable whenever the sun crosses -5.DEG. to +3.DEG. elevation, and the method can yield useful results whenever the sun makes a significant excursion into that elevation range. Early results based on data taken on land at 48.DEG.N latitude confirm the predictions vs. season, and show promising performance when compared with earlier threshold-based methods.

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