According to researchers (who actually outfitted a tern with a geolocator tracking device), the arctic tern (Sterna paradisaea) has the longest known migration distance, flying from its Greenland breeding grounds to the Weddell Sea on the shores of Antarctic—a round trip that can total as much as 44,000 miles (71,000 kilometers). Running a close second appears to be the Sooty shearwater (Puffinus griseus), a bird that migrates nearly 40,000 miles (64,000 kilometers) a year, flying from New Zealand to the North Pacific Ocean every summer in search of food. Other animals whose migration distance varies depending on the species are as follows: For example, gray whales (Eschrichtius robustus) migrate the longest of any whale, migrating about 12,500 miles (20,117 kilometers); the caribou (Rangifer tarandus caribou) migrates the longest for a land animal—about 700 miles (1,127 kilometers); and the desert locust (Schistocerca gregaria) migrates the longest for any insect—about 2,800 miles (4,506 kilometers).