rat eradication in the Galapagos

[Chlidonias]

Millions of rats to be killed in Galapagos Islands - World - NZ Herald News

15 November 2012

The unique bird and reptile species that make the Galapagos Islands a treasure for scientists and tourists must be preserved, Ecuadorean authorities say - and that means the rats must die, hundreds of millions of them.

A helicopter is to begin dropping nearly 22 tons of specially designed poison bait on an island Thursday (local time), launching the second phase of a campaign to clear out by 2020 non-native rodents from the archipelago that helped inspire Charles Darwin's theory of evolution.

The invasive Norway and black rats, introduced by whalers and buccaneers beginning in the 17th century, feed on the eggs and hatchlings of the islands' native species, which include giant tortoises, lava lizards, snakes, hawks and iguanas. Rats also have depleted plants on which native species feed.

The rats have critically endangered bird species on the 19-island cluster 1,000km from Ecuador's coast.

"It's one of the worst problems the Galapagos have. (Rats) reproduce every three months and eat everything," said Juan Carlos Gonzalez, a specialist with the Nature Conservancy involved in the Phase II eradication operation on Pinzon island and the islet of Plaza Sur.

Phase I of the anti-rat campaign began in January 2011 on Rabida island and about a dozen islets, which like Pinzon and Plaza Sur are also uninhabited by humans.

The goal is to kill off all non-native rodents, beginning with the Galapagos' smaller islands, without endangering other wildlife. The islands where humans reside, Isabela and Santa Cruz, will come last.

Previous efforts to eradicate invasive species have removed goats, cats, burros and pigs from various islands.

Pinzon is about seven square miles (1,812 hectares) in area, while Plaza Sur encompasses just 24 acres (9.6 hectares).

"This is a very expensive but totally necessary war," said Gonzalez.

The rat infestation has now reached one per square foot (about 10 per square meter) on Pinzon, where an estimated 180 million rodents reside.

The director of conservation for the Galapagos National Park Service, Danny Rueda, called the raticide the largest ever in South America.

The poisoned bait, developed by Bell Laboratories in the United States, is contained in light blue cubes that attract rats but are repulsive to other inhabitants of the islands. The one-centimetre-square cubes disintegrate in a week or so.

Park official Cristian Sevilla said the poison will be dropped on Pinzon and Plaza Sur through the end of November.

A total of 34 hawks from Pinzon were trapped in order to protect them from eating rodents that consume the poison, Sevilla said. They are to be released in early January.

On Plaza Sur, 40 iguanas were also captured temporarily for their own protection.

Asked whether a large number of decomposing rats would create an environmental problem, Rueda said the poison was specially engineered with a strong anti-coagulant that will make the rats dry up and disintegrate in less than eight days without a stench.

It will help that the average temperature of the islands is 24 degrees Celsius, he added.

The current $1.8 million phase of the project is financed by the national park and non-profit conservation groups including Island Conservation.

The Galapagos were declared protected as a UNESCO Natural Heritage site in 1978. In 2007, UNESCO declared them at risk due to harm from invasive species, tourism and immigration.

 

[zooboy28]

How will they stop the native rodents eating the bait? According to wikipedia there are at least two such species: the Santiago Galapagos Mouse and the Fernandina Galapagos Mouse, both are listed as vulnerable by IUCN.

 

[Chlidonias]

I don't know how they would deal with that on the islands with native rodents. However most of the native rodents on the Galapagos Islands are now extinct: there were at least seven species of rice rats, of which only three survive and they are restricted to specific islands (namely Santiago, Fernandina, and Santa Fe). Given that the probable reason for the endemic rodents' extinction was the introduction of black rats I'd say the islands the rice rats still live on are free of black rats anyway.

The really good thing about all this is that once the black rats are eradicated from the islands, the surviving species of rice rats can be translocated to new islands.

 

[nanoboy]

I wonder if they could develop a similar rabbit poison for us?

I am sceptical about eradication programs that purport to be poisonous to one species, but harmless/repulsive to others. I hope it doesn't backfire because of some unforeseen consequences.

 

[DavidBrown]

I wonder if they could develop a similar rabbit poison for us?

I am sceptical about eradication programs that purport to be poisonous to one species, but harmless/repulsive to others. I hope it doesn't backfire because of some unforeseen consequences.

Rats have been poisoned on several islands. The Channel Islands National Park in California has eliminated rats from some islands, and I think that much of this work has been pioneered in New Zealand where many islands have been de-ratted. Pehaps Chlidonias can comment on this.

One aspect of this that I'm curious about is what the hawks eat. If the invasive rats have caused the native rats to go extinct and the invasive rats get eliminated, what are the hawks going to eat?

 

[Kifaru Bwana]

I wonder if they could develop a similar rabbit poison for us?

I am sceptical about eradication programs that purport to be poisonous to one species, but harmless/repulsive to others. I hope it doesn't backfire because of some unforeseen consequences.

The programme has already been completed in some of the Galapagos islands as a trial and error exercise. So, dealt with!

 

[nanoboy]

Rats have been poisoned on several islands. The Channel Islands National Park in California has eliminated rats from some islands, and I think that much of this work has been pioneered in New Zealand where many islands have been de-ratted. Pehaps Chlidonias can comment on this.

One aspect of this that I'm curious about is what the hawks eat. If the invasive rats have caused the native rats to go extinct and the invasive rats get eliminated, what are the hawks going to eat?

That's fantastic that this is a tried and tested solution then. I don't have an answer regarding the hawks, but as Chlidonias said earlier, maybe native rats will be reintroduced.

 

[Chlidonias]

I am sceptical about eradication programs that purport to be poisonous to one species, but harmless/repulsive to others. I hope it doesn't backfire because of some unforeseen consequences.

in this case it will almost certainly be a mammal-specific toxin, not a rat-specific toxin so there should be little danger to other species on the islands (I had a hunt around to see if I could find which toxin it was but only found that it was a specially-developed one from Bell Laboratories in America [which they donated for the cause]). There may be the danger of minimal incidental poisoning, which would be why a small number of hawks have been held in captivity while the drop is undertaken.

One aspect of this that I'm curious about is what the hawks eat. If the invasive rats have caused the native rats to go extinct and the invasive rats get eliminated, what are the hawks going to eat?

the Galapagos hawk is a catholic feeder of any small animal, including young iguanas etc. I do imagine the intent after elimination of the foreign rodents is reintroduction of the endemic ones.

 

[Kifaru Bwana]

in this case it will almost certainly be a mammal-specific toxin, not a rat-specific toxin so there should be little danger to other species on the islands (I had a hunt around to see if I could find which toxin it was but only found that it was a specially-developed one from Bell Laboratories in America [which they donated for the cause]). There may be the danger of minimal incidental poisoning, which would be why a small number of hawks have been held in captivity while the drop is undertaken.


the Galapagos hawk is a catholic feeder of any small animal, including young iguanas etc. I do imagine the intent after elimination of the foreign rodents is reintroduction of the endemic ones.

I would expect the extant rodent spp. from within the other rat-free Galapagos Islands will be used as role models to re-occupy the erstwhile ecological niche.

 

[nanoboy]

in this case it will almost certainly be a mammal-specific toxin, not a rat-specific toxin so there should be little danger to other species on the islands (I had a hunt around to see if I could find which toxin it was but only found that it was a specially-developed one from Bell Laboratories in America [which they donated for the cause]). There may be the danger of minimal incidental poisoning, which would be why a small number of hawks have been held in captivity while the drop is undertaken.


the Galapagos hawk is a catholic feeder of any small animal, including young iguanas etc. I do imagine the intent after elimination of the foreign rodents is reintroduction of the endemic ones.

If it is mammal specific rather than rat specific, isn't that logically a bad thing as it could pose a danger to other mammals?

 

[Chlidonias]

If it is mammal specific rather than rat specific, isn't that logically a bad thing as it could pose a danger to other mammals?

reading my post back it wasn't clear what I meant, but I was referring to your comment about toxins specific to a species ("I am sceptical about eradication programs that purport to be poisonous to one species, but harmless/repulsive to others": I was basically saying it wouldn't be specific to rats, but probably to mammals in general [as opposed to a general toxin that kills everything]).

However the only mammals on the targeted islands are introduced ones, apart for the sealions and bats which wouldn't be at risk anyway.

 

[The Vegan]

I am also skeptical about this program. As my name may suggest, I oppose killing... but I have other concerns here, namely, the longevity of the poison. Will it contaminate water on the island?

 

[Chlidonias]

I am also skeptical about this program. As my name may suggest, I oppose killing... but I have other concerns here, namely, the longevity of the poison. Will it contaminate water on the island?

if its anything like 1080 (which it is probably similar to or based upon) then no. It will degrade rapidly and be harmless.

 

[nanoboy]

reading my post back it wasn't clear what I meant, but I was referring to your comment about toxins specific to a species ("I am sceptical about eradication programs that purport to be poisonous to one species, but harmless/repulsive to others": I was basically saying it wouldn't be specific to rats, but probably to mammals in general [as opposed to a general toxin that kills everything]).

However the only mammals on the targeted islands are introduced ones, apart for the sealions and bats which wouldn't be at risk anyway.

Ok I get you. Well it sounds like a good idea then. Here's hoping that it works.