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How do they make sure the other animals don't eat the rat poison? Is it just that no native species would find the bait tasty?

jandrese 8y ago
The Galapagos has only a handful of native species, so testing it with all of them might be feasible. At least if you count all of the finches at one species. :)
- KineticLensman 8y ago
  The specific island involved, North Seymour island, [0] has the following species: frigate birds, blue footed boobies, sea lions, marine iguanas, swallow-tailed gulls, snakes, herons, hawks, sharks, rays [0] https://www.gogalapagos.com/islands/north-seymour/ https://www.gogalapagos.com/islands/north-seymour/
  - bayesian_horse 8y ago
    I doubt this is an exhaustive list. They left out the rats ;-)
rrauenza 8y ago
And they must be confident the scavengers won't eat the poisoned rats? Or that it is worth the trade off?
- bayesian_horse 8y ago
  There are often problems with cats and dogs eating poisoned rodents. This can be a serious emergency, but it develops rather slowly at first, and is often treated with blood transfusions, Vitamin K and lots of patience. One way to lessen this effect would be to use doses so low that the rats will die but which would be diluted and metabolized by the time the animal actually dies. The most popular rat poisons involve some sort of anti-clotting agent, to ensure a high mortality while keeping the animal alive long enough not to discourage other rats from eating the bait. Overall the idea is probably to kill a higher percentage of the rats than of all the other species. I believe (but I don't know for certain) that invertebrate scavengers may be immune to those poisons.
Jedd 8y ago
It's not clear from the article, but my guess is (as others noted) they'd have some level of confidence from testing against the other inhabitants of the island. They could engineer the baits to look, smell, and taste especially unpalatable to the birds and iguanas there, or ship the baits in wrappings that rats could & would be able to penetrate, say a thick cellulose or cardboard wrap containing a single serve. Typically the problem with baiting in this way is what happens when those animals die, and other animals eat the carcass. This isn't discussed either, but it sounds like a) local wildlife aren't big on scavenging dead animals, and b) the wildlife losses from this would be significantly smaller than from the rat infestation.
- bayesian_horse 8y ago
  Oh, I can think of a dozen or so ways it MIGHT work, but I'm curious about how they actually did it. One way would be to make sure the amount of rat poison is precisely calibrated so that the rats will get to it first and not leave a lot behind for other animals to consume.
richdougherty 8y ago
It could be something like 1080 which harms mammals but is safe for birds. This poison is used a lot in New Zealand since we have a lot of native birds but only two species of native mammals (bats). https://en.m.wikipedia.org/wiki/1080_usage_in_New_Zealand https://en.m.wikipedia.org/wiki/1080_usage_in_New_Zealand

jandrese 8y ago

The Galapagos has only a handful of native species, so testing it with all of them might be feasible. At least if you count all of the finches at one species. :)

KineticLensman 8y ago
The specific island involved, North Seymour island, [0] has the following species: frigate birds, blue footed boobies, sea lions, marine iguanas, swallow-tailed gulls, snakes, herons, hawks, sharks, rays [0] https://www.gogalapagos.com/islands/north-seymour/ https://www.gogalapagos.com/islands/north-seymour/
- bayesian_horse 8y ago
  I doubt this is an exhaustive list. They left out the rats ;-)

rrauenza 8y ago

And they must be confident the scavengers won't eat the poisoned rats? Or that it is worth the trade off?

bayesian_horse 8y ago
There are often problems with cats and dogs eating poisoned rodents. This can be a serious emergency, but it develops rather slowly at first, and is often treated with blood transfusions, Vitamin K and lots of patience. One way to lessen this effect would be to use doses so low that the rats will die but which would be diluted and metabolized by the time the animal actually dies. The most popular rat poisons involve some sort of anti-clotting agent, to ensure a high mortality while keeping the animal alive long enough not to discourage other rats from eating the bait. Overall the idea is probably to kill a higher percentage of the rats than of all the other species. I believe (but I don't know for certain) that invertebrate scavengers may be immune to those poisons.

Jedd 8y ago

It's not clear from the article, but my guess is (as others noted) they'd have some level of confidence from testing against the other inhabitants of the island. They could engineer the baits to look, smell, and taste especially unpalatable to the birds and iguanas there, or ship the baits in wrappings that rats could & would be able to penetrate, say a thick cellulose or cardboard wrap containing a single serve. Typically the problem with baiting in this way is what happens when those animals die, and other animals eat the carcass. This isn't discussed either, but it sounds like a) local wildlife aren't big on scavenging dead animals, and b) the wildlife losses from this would be significantly smaller than from the rat infestation.

bayesian_horse 8y ago
Oh, I can think of a dozen or so ways it MIGHT work, but I'm curious about how they actually did it. One way would be to make sure the amount of rat poison is precisely calibrated so that the rats will get to it first and not leave a lot behind for other animals to consume.

richdougherty 8y ago

It could be something like 1080 which harms mammals but is safe for birds. This poison is used a lot in New Zealand since we have a lot of native birds but only two species of native mammals (bats). https://en.m.wikipedia.org/wiki/1080_usage_in_New_Zealand https://en.m.wikipedia.org/wiki/1080_usage_in_New_Zealand