Invasive Rats in Galapagos
From Galapedia
| Invasive Rats in Galapagos in Galapagos | |
 Black Rats in Galapagos. | |
| Diet: | fruits, seed, trash, bird and reptile eggs, young animals |
|---|---|
Invasive rat eradication
Rats are an aggressive invasive species that prey upon native wildlife and compete with endemic rodent species for territory. The Charles Darwin Foundation's (CDF) long term plans for the restoration of Galapagos include rat eradication programs.
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Arrival in Galapagos
Introduced rats (the black rat (Rattus rattus) and the Norway Rat (Rattus norvegicus)) were brought to Galapagos in boats that arrived from the end of the seventeenth century onwards. Rats are still found on many boats that visit the islands and there is always a danger of new introductions. At present invasive rats are found on all inhabited islands as well as Santiago Island and many small islands.
In Galapagos, rats can:
- adapt to the harsh environment such as lava fields
- obtain food from many sources such as fruits, seed, and trash. They also feed on bird or reptile eggs and young animals.
- compete aggressively for food
- breed rapidly when there is adequate water for survival
Impact on Galapagos
Introduced rats affect the integrity of native ecosystems and cause extinctions of species on islands worldwide. Rats are agricultural and household pests and carry diseases which affect human and animal health.
Rats impact on a vast range of native and endemic species, including endemic rice rats (Oryzomys, Nesoryzomys, and Megaoryzomys species) and ground-nesting birds such as the Dark-Rumped Petrels (Pterodroma phaeopygia). Because rats are active climbers they have also been implicated in population declines of tree nesting birds such as the Mangrove Finch (Camarhynchus heliobates). Giant tortoises and other reptiles, invertebrates and a wide range of plants are also affected.
The Santiago Rice Rat (Nesoryzomys swarthi) was thought to be extinct, as a result of the presence of black rats and feral cats; however visiting scientists discovered a small population in 1997. The future of these endangered endemic rats depends upon the eradication of invasive black rats on Santiago Island.
CDRS research activities
Long term plans for the restoration of Galapagos necessitate the eradication of introduced rats on all islands. Worldwide, rats have been eradicated from many islands using ground or aerial baiting methods.
CDRS and visiting scientists are working with the Galapagos National Park Service (GNPS) on experimental techniques to eradicate rats on Santiago. Tests of a selective bait station showed that endemic rice rats could not access the bait, whereas black rats did. This method may help control black rats in areas where endemic rats also occur.
Eradication of black rats on nearby islets has started. If suitable, these islets may be used as refuges for the Santiago rice rat.
For the future
CDF will use the results from these studies to further develop a researchbased, species-specific eradication strategy to remove introduced rats from Galapagos. The next stages in this process are:
- to eradicate introduced rats on small and medium sized islands where re-invasion is unlikely.
- to learn how to deal with non-targeted species
- to develop the capacity to attempt rat eradication on large islands such as Floreana and other inhabited islands
- to develop strategies to prevent the reintroduction of rats from boats docking in the islands.
The successful eradication of introduced rats from Galapagos will pave the way for the total restoration of Santiago and other islands. CDF's goal is to return Galapagos to the pristine place it was before the arrival of rats challenged the future of its endemic and native species. By working with organizations such as GNPS and with the community, it will be possible to achieve this goal: a Galapagos without invasive rats.
