Rock of Gibraltar may have originated from an escape of North African animals transported to Spain; it is also possible that the original Gibraltar macaques are a remnant of populations that are known to have spread throughout Southern Europe during the Pliocene, up to 5.5 million years ago. Some animals of the Rock have been reintroduced by the Alameda Wildlife Conservation Park who have three Barbary macaques. The Rock of Gibraltar, at the head of the Strait, is a prominent headland, which accumulates migrating birds during the passage periods. The vegetation on the Rock, unique in southern Iberia, provides a temporary home for
Rock of Gibraltar shipping routes to the Mediterranean. In February 1997, it was revealed the British had a secret plan called to conceal service men in tunnels beneath the Rock in case the Germans captured it. The team in the rock would have radio equipment with which to report enemy movements. A six-man team waited under cover at Gibraltar for two and half years. The Germans never got close to capturing the rock and so the men were never sealed inside. The team was disbanded to resume civilian life when the war ended. The saying "solid as the Rock of Gibraltar" is used