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The Impact of Invasive Rodents on Endemic Rice Rats in the Galapagos


The remote Galapagos islands were uninhabited until the 17th century. Geographic isolation and late human occupation allowed the unique ecosystem of the Galapagos to remain largely intact, and the unusual fauna of the archipelago inspired Darwin’s theory of evolution by natural selection. The biodiversity of the Galapagos is now under threat, particularly from exotic species introduced by man. Our challenge is to understand the impact of invasive species on the endemic fauna, in order to prioritise and plan appropriate conservation action.


Why is this project important?

The Galapagos are traditionally associated with charismatic marine iguanas, giant tortoises and blue-footed boobies. However, the archipelago also hosts a fascinating, yet relatively unknown, group of endemic rodents. These suffered considerable impact during the twentieth century, and five of the eight species were considered extinct. One, the endemic Santiago Rice Rat, was recently rediscovered.

Native island faunas worldwide are adversely affected by introduced mammals, and the extinction of endemic rodents on the Galapagos may be linked with the introduction of exotic rodents. Non-native Black Rats arrived on Santiago in the late 1600s, and have subsequently spread across the archipelago. We are studying the impact of Black Rats on Rice Rats to obtain information on exotic-endemic species interactions, and a detailed picture of the ecology and behaviour of the poorly understood Rice Rat. This research will inform us in devising effective plans for conserving the endemic rats of the Galapagos in particular, and protecting native island fauna from invasive species generally.

What are we doing?

We have gathered baseline data on the population dynamics and habitat use of both species. Movements and activity patterns have been monitored by radio-tracking. We have just completed a Black Rat removal experiment that will quantify the impact of Black Rats on the survival and reproduction of the Santiago Rice Rat. Exotic rats may compete with endemic rodents either directly, through interference or aggression, and/or indirectly by competing for resources (diet, shelter, space). They may also spread diseases to their native counterparts. Research is underway to explore all three of these potential mechanisms of conflict.




The Santiago Rice Rat; recently rediscovered

How is this project making a difference?

Deliverables

This project is designed to determine whether there is an urgent need to control invasive Black Rats on the Galapagos. We will produce an action plan for the Santiago Rice Rat, and our recommendations may be applicable to other endemic rice rat species on the Galapagos. Findings will be distributed to the Galapagos National Park Service and to the Charles Darwin Research Station, and communicated through science journals, presentations and the media.

Cascade effects

The Galapagos community will benefit through safeguarding the natural beauty of the Galapagos, and, so, their biggest industry, nature tourism. Our recommendations for further study will aim to involve and enthuse the local community. Findings will be made available to ecologists and wildlife managers worldwide where similar conflicts exist.

How can you help?

We warmly acknowledge the generous financial support of the Galapagos Conservation Trust. This has allowed us to establish a highly efficient protocol entailing three intensive field seasons of data collection (2002-2004). We now urgently seek a further injection of funds to cover a field assistant in the final year. Long working hours and isolation dictate that our full-time researcher, Donna Harris, must be accompanied by a field assistant. Indeed, Park  (GNPS) regulations state that this is compulsory. An extremely experienced and dedicated person has been providing his assistance on a voluntary basis for two years, but he can no longer afford to do so. We wish to retain his valuable help and to reward his efforts by paying him a nominal amount in the final year.

We also need money to cover additional requirements for field equipment and inter-island transport. Scope to cover unexpected contingencies can hugely improve flexibility and allows us to take advantage of unique research opportunities as they arise.


Donna Harris and Rice Rat

YOU CAN HELP THIS PROJECT
Target to be raised
£27,000

You can find out about the budget for this project by contacting us. See our contact details.

If you are interested in finding out more about the science involved in this project, we would be happy to send you further information.

WildCRU is part of the University of Oxford, a tax- exempt charity. To maximise tax benefits to both donors and WildCRU, please see Donations.

Principal funders
Galapagos Conservation Trust

Main Partners
Charles Darwin Research Station Galapagos National Park Service

Text by Sandra Baker