來源： Island Conservation and Ecology Group, 2004
During the eradication process, around a dozen Geochelone carbonaria tortoises were discovered. While these species do occur in the Caribbean (introduced there from South America by Native Americans in pre-Columbian times), there had been no previous reports from this particular island. It was later discovered that these tortoises had been brought on the island just a few years earlier by a private breeder. While the rats were present, the tortoises' effect on the islands vegetation was limited because their reproduction was brought to a halt by rats eating their eggs. It seemed likely that they might be able to outcompete the 20 racers, which were subsequently reintroduced, as Geochelone carbonaria probably occupied the best egg-laying spots (few sites have appropriate soil/substrate concentrations) and its growing population was feeding selectively on certain vegetation. No natural enemies of these tortoises occur on the island. Therefore this species is closely watched and its impacts studied. If competition on nesting substrate occurs, it will be removed and brought back to captive facilities on mainland Antigua. So far, no such problem has occured and the racer population has recovered to a new high of 150 animals, a good proporton of which lives on Green Island.
A rat eradication project was conducted by the Antiguan Racer Conservation Project (ARCP) in 2001, under the auspicies of the Caribbean Programme of Fauna & Flora International. The ARCP is funded by the Walt Disney Conservation Foundation, Durrell Wildlife Conservation Trust, Roger Vere Foundation, Lindeth Charitable Trust and the Bernhardine Fund. As is common in the Caribbean region, the ARCP aimed to eradicate both Rattus rattus and Herpestus aurupunctatus (javanicus) from Green Island, an unpopulated 43 hectare island off the Antiguan east coast. As it turned out, only Rattus rattus was found and was eradicated in 2001. The eradication was achieved over four weeks using brodifacoum (50ppm) bait stations on a 20 x 20m grid, at a cost of c. US$15,000. Non-target species included various bird species, in particular egrets and raptors such as Pandion haliaetus, Nyctanassa violacea. Permanent bait stations are maintained on the island to prevent reinvasion (K. Varnham, pers. comm.). The possible occurance of Capra hircus, Mus musculus and Herpestus aurupunctatus (the latter having been reported from Green Island before) was carefully investigated but no proof was found in the end. Thus the project finally only eradicated around two thousand rats from the island. An Oct 2001 report by Karen Varnham on a follow-up visit is available (G. Meier, pers. comm.).
The vegetation of Green Island (43 ha) is grassy and forested.
捕食: In the late 1990s a large Rattus rattus population had become established on Green Island and within a very short time it had eradicated the endemic and critically endangered Antiguan Racer (Alsophis antiguae). Only 100 individuals were left on a tiny neighbouring island. Seabirds, hummingbirds, pigeons, tree seedlings, seaturtles nesting sites and endemic reptiles of Anolis and Ameiva were also depleted by the rats with enormous speed.
最後修改 ： 23/03/2006 1:23:21 p.m.