Sun compass in animals internal clock to determine their heading, and that they had learnt the actual direction down to the sea on their particular beach. Lockley's experiments with Manx shearwaters ("Puffinus puffinus") showed that when released "under a clear sky" far from their nests (in Skokholm), the seabirds first oriented themselves and then "flew off in a direct line for Skokholm", making the journey rapidly. For example, one of the birds, released at Boston airport, arrived in Skokholm 12½ days later; Lockley calculated that if the birds flew for 12 hours per day, they must have travelled at 20 miles per hour, their
Wedge-tailed shearwater (in common with the other shearwaters) as an adaptation for swimming. This species is related to the pan-Pacific Buller's shearwater, which differs much in colour pattern, but also has a wedge tail and a thin black bill. They make up the "Thyellodroma" group, a superspecies of the large shearwaters that were for a long time included in the genus "Puffinus". Wedge-tailed shearwaters feed pelagically on fish, squid and crustaceans. Their diet is 66% fish, of which the most commonly taken is goatfish. It was thought that the species mostly took food from surface feeding, observations of feeding wedge-tails suggested that