It's easy to prove that big birds like gulls will cross oceans when they migrate, but tiny birds are another matter -- the trackers you need are usually enormous in comparison. The Vermont Center for Ecostudies wasn't daunted, though. It successfully tested extra-small geolocators on blackpoll warblers, migratory songbirds that are too small and light (0.4oz) to shoulder previous sensors. The newer device weighs just 0.02oz, and is no bigger than a dime. As you can see above, it was more of a minor inconvenience than a heavy burden.
The miniscule monitor helped confirm a long-suspected theory about the warbler. As it turns out, the bird flies roughly 1,600 miles non-stop across the Atlantic, from the northeastern US to the Caribbean -- no mean feat when it has to stay airborne for as long as three days. That would have been nearly impossible to know using radar or on-the-ground observers. As such, technology like this might just fill in a lot of gaps in nature studies and help us humans both understand and protect smaller animals.
[Image credit: Vermont Center for Ecostudies]