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
Puffinus and often give eerie contact calls on their night-time visits. They lay a single white egg. They feed on fish, squid and similar oceanic food. Some will follow fishing boats to take scraps, notably the sooty shearwater; these species also commonly follow whales to feed on fish disturbed by them. Traditionally, "Puffinus" has been grouped with the "Procellaria" and "Calonectris" shearwaters. However, more recent results have determined that the genus is apparently paraphyletic and while in part very close to "Calonectris", forms a clade with the genera "Pseudobulweria" and "Lugensa", which were formerly presumed to be gadfly petrels, and can