The blue iguana (Cyclura lewisi), also known as the Grand Cayman ground iguana, Grand Cayman blue iguana or Cayman Island rock iguana, is an endangered species of lizard which is endemic to the island of Grand Cayman. It was previously considered to be a subspecies of the Cuban iguana, Cyclura nubila, but in a 2004 article Frederic J. Burton reclassified it as a separate species because according to him the genetic differences discovered four years earlier between the different C. nubila populations warranted this interpretation. The blue iguana is one of the longest-living species of lizard (possibly up to 69 years). The preferred habitat for the blue iguana is rocky, sunlit, open areas in dry forests or near the shore, as the females must dig holes in the sand to lay eggs in June and July. A possible second clutch is laid in September. The blue iguana's herbivorous diet includes plants, fruits, and flowers. Its color is tan to gray with a bluish cast that is more pronounced during the breeding season and more so in males. It is large and heavy-bodied with a dorsal crest of short spines running from the base of the neck to the end of the tail. The iguana was possibly abundant before European colonization; but fewer than 15 animals remained in the wild by 2003, and this wild population was predicted to become extinct within the first decade of the 21st century. The species' decline is mainly being driven by predation by cats and dogs, and indirectly by reduction in suitable habitat as fruit farms are converted to pasture for cattle grazing. Since 2004, hundreds of captive-bred animals have been released into a preserve on Grand Cayman run by a partnership headed by the Durrell Wildlife Conservation Trust, in an attempt to save the species. At least five non-profit organizations are working with the government of the Cayman Islands to ensure the survival of the blue iguana. Taxonomy Its specific name lewisi commemorates the name of the scientist who collected the holotype of this species, Charles Bernard Lewis. The closest relatives are the Cuban iguana (Cyclura nubila) and the Northern Bahamian rock iguana (C. cychlura). It can be genetically distinguished from the subspecies found on Little Cayman and Cayman Brac known as C. nubila caymanensis, although it can interbreed with this subspecies and produce fertile offspring. In 1938 Lewis of the Institute of Jamaica