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
Europa Island 100 pairs, probably of the subspecies "Puffinus lherminieri bailloni" previously considered endemic to the Mascarene Islands), dimorphic egrets and Caspian terns. The island is also home to an endemic subspecies of white-tailed tropicbird ("Phaethon lepturus europae"). There are three species of landbirds present, one of which is an endemic subspecies of the Malagasy white-eye ("Zosterops maderaspatanus voeltzkowi"). Additionally, the island is also home to its own species of hissing cockroach. Climate is affected by the Agulhas Current with water temperatures usually above 30 °C, southeast trade winds during the (austral) winter and occasional cyclones. While the island has probably been