"Rats, Humans and their impacts on islands"
Conference in Hawaii by Liz Westbrooke

Environmental News Issue 10

At the end of March John Ogden and I attended the first ever ‘Rats, Humans and their impacts on islands’ conference at the University of Hawaii. People working on rat eradication projects came from all over the world and shared information via some 51 papers presented and 20 large posters on display.

There were folks working in the Caribbean and the US Virgin Islands, various nationalities examining the Seychelles, Madagascar, Canary and Mediterranean islands, bio-security specialists reporting on measures taken in the Aleutian Islands of Alaska, Australians helping locals on Pacific Islands such as Viwa Island off Fiji, and German and US teams studying the deforestation of Rapa Nui (Easter Island). There were of course many Hawaiians since they were the hosts and there were lots of New Zealanders as this seems to be one of our specialist fields (70 islands eradicated now).

The presenters were a mixture of project managers, ecologists, archaeologists, linguists, anthropologists, botanists and DNA specialists! John gave an excellent and amusing presentation on the rat statistics gathered on Great Barrier Island including those from Awana, Glenfern and Windy Hill.

Sitting through all these interesting papers, I realized how lucky we are in New Zealand. Hawaii has little of its natural vegetation cover left, even their iconic coconut palm is an introduced plant. They have to start often by protecting an area with a fence, not a rodent proof fence, simply a fence to keep pigs and ungulates out. Once this is achieved they can start to study and restore the area inside. They do not enjoy our rainfall, thus their plants do not regenerate as vigorously as ours do. And they have introduced animal pests such as snakes and mongoose to contend with.

So what else did we learn that was new? Lots and lots of detail! The main conclusion I came to however is that everyone working in this area needs to integrate what is known about rat behaviour into the process. Effort must be targeted more effectively to trim cost and minimize toxin use. Rather than using strict grids of equidistant baits and traps, management control must intensify around rat food sources (e.g. miro trees), in wetter habitats, near food ‘caching’ spots, and in the lightly forested areas.

Of course that is all based on research done in other places. To be really effective on Great Barrier Island however, we need to confirm these results by gathering specific information about rat behaviour and preferences in this particular micro climate and northern bush type. And then of course there are the mice... More research is needed.