So far research on bird travel and migration behavior was largely guesswork, especially the actual bit of traveling. It is well known where they life and what their destination of migration is over the course of the seasons. What is largely unknown is the bit in between. What is their exact rout of travel, how fast do they travel and how often do they rest, these are the main questions regarding bird migration behavior.
Scientists have tested many techniques, from banding a bird's legs (which was until recently the most successful of the methods), to tracking flocks with radar to even using satellites, all with not much success.
It is known that birds can fly at a rather fast speed of around 60 miles and hour and that they do travel almost half way around the globe during their migration. Biologists now where interested in the details of this knowledge but to receive new data they had to find a new method of observing the birds’ movement.
A new mini tracking device has enabled researchers at York University in Toronto to tag rather small songbirds. The main problem here is the weight. Engineers at the British Antarctica Survey have developed a small light weigh tracker to follow the trips of albatrosses, rather large birds. The scientists at York where able to minimize the technology to a total weight of 1.5 gram. It sits on the birds back and is hold in place with two straps around their legs, just like a miniature backpack. The sensor is not exactly a GPS, it is a solar geolocator. It collects and store data in relation to the sun.
A total of 34 purple martin birds where tagged in summer 2007. Only seven of them could be recaptured a year later. Nevertheless the data was exiting. The data showed that the birds flew two to six times faster going north, than going south. Researchers also discovered that they actually flew much faster than initially guessed. Information about the stopover points will help to protect birds, especially songbirds that are in steep decline.
Image by (main) Patrick M Kramer; (inset) Tim Morton - A purple martin bird wearing a geolocator.
Image source NYTimes/Science
infos from NYTimes/science/environment
and from scienceno.sciencemag