I recently took a trip over to Bermuda to explore the introduced Anolis lizard (anole) communities. Over the past century 3 species of anole have become established on the island, all originating from different Caribbean islands. Rumours were circulating of a 4th species that had newly colonised, the wonderfully adaptable and incredibly successful invasive Cuban brown anole Anolis sagrei. Joined by former FIU grad student Sean Giery, led by Bermuda’s wildlife conservation expert Mark Outerbridge, and armed only with lizard nooses and a scooter each, we set out to confirm if this was true.
Anolis grahami, from Jamaica, was the first species of anole to be introduced to Bermuda. It is a classic example of biological management gone wrong. In 1905, 71 individuals (26 males and 45 females) collected in Kingston, Jamaica, were captured, transported and introduced to Bermuda in an effort to control the fruit fly Ceratitis capitata. They were an obvious choice; voracious insect eaters, as well as being “harmless and very entertaining reptile[s]”. Within 6 weeks they had spread ~1 mile, and by 1963 the species had colonised all but an extreme northwestern tip on the island archipelago, including several small offshore islands. In 1953, an established colony of A. extremus (then A. roquet), a charmingly shy lizard from Barbados in the Lesser Antilles, was first found on Ireland Island – along the same northwestern archipelago that A. grahami had yet failed to colonise. It was most likely brought over as an accidental stowaway on a ship docking at H.M. Dockyard, the British naval base. It’s distribution remained limited, and in a decade it had hardly ventured outside of that original archipelago peninsula.
A. grahami was then joined in the centre of Bermuda in 1956 by another Lesser Antillean congeneric, A. leachi, from the distant shores of Antigua and Barbuda. Reasons for their introduction are unknown, however like A. grahami they spread relatively rapidly, such that by 1963 they were common within a 1 mile radius of the site of their original observation. A re-evaluation of species’ distributions on Bermuda in 1991 revealed that although A. grahami and A. extremus had conserved their ranges from 1963, A. leachi had continued to expand and was now found over large areas of mainland Bermuda radiating from the original site of introduction.
There is only one native lizard on Bermuda, the IUCN critically endangered Bermudan skink Plestiodon longirostris. These days they are restricted primarily to small offshore islands, such as Nonsuch Island (picture below). Many of these islands are characterised by short, scrubby vegetation which provide a strong defensive structural habitat for these skinks.
And what about the brown anole? You’ll just have to read the published articles to find out!