Sooty terns Onychoprion fuscatus, also known locally as wideawakes because of their call, nest in large colonies south of the runway at Mars Bay and Wideawake Fairs. They lay one or two eggs in shallow indentations in the lava. The breeding cycle is approximately every 9.6 months. After breeding, they spend their time away at sea. They do not touch down on land during this time and sleep 'on the wing'. While they are not endemic to Ascension, the territory’s population is believed to consist of around 350,000 terns, which is possibly 4% of the global population.