GPS trackers weighing just 0.95 grammes will help scientists track the movements of three species of elusive nocturnal birds that stay in the Westman Islands, South Iceland, for a part of each year, RÚV reports. The three species are the manx shearwater (Puffinus puffinus), Leach’s petrel (Oceanodroma leucorrhoa), and the storm petrel (Hydrobates pelagicus), all of which winter in the southern hemisphere – on both sides of the Atlantic.
“This has never been done in Iceland before, and we are in fact mapping the feeding areas of these species,” explained Erpur Snær Hansen, director of the South Iceland Nature Research Centre. Results from the miniscule trackers placed on Leach’s petrels and manx shearwaters have already begun to arrive, while data from the storm petrels are expected to arrive later this summer.
Travelled 600 kilometres to feed
The three species are related and are all nocturnal. “They only come ashore to the outlying Westman Islands at night, so they are rarely seen anywhere else,” Erpur stated. He compared the petrels’ flight to that of bats, saying they were “mysterious in many ways.”
The GPS trackers have revealed that the Leach’s petrels in the Westman Islands feed to the west of the archipelago, at the edge of the continental shelf. However, data shows that individuals sometimes travel much farther. “One of them decided to go all the way to Rockall, which is 600 kilometres [373 miles] to the south, and they go quite far,” Erpur remarked. “They go to the Mid-Atlantic Ridge where the big whales are, so they go south and across a very large area.”
Numbers have decreased in the Atlantic
Placing the minuscule trackers on the birds is not easy. “It’s a bit of a hassle because they live underground, and we need to find them and get them out,” Erpur explained. “We play their call and they answer us and then we know where they live, but it’s another challenge altogether to get in there, grab them, and put the equipment on.” The GPS devices do not include transmitters, so the birds must be retrieved in order to read the data.
The Leach’s petrels that summer in Iceland winter in both Namibia and Brazil. Manx shearwaters winter in Argentina. Erpur says the species are not numerous and the number of Leach’s petrels in the Atlantic has decreased. The data is expected to help evaluate how the birds are doing, as well as compare the two petrel species.