Monday, April 30, 2018

First We Kill All the Rats

From Ted Williams comes this story of the miracle recovery on Palmyra Island in the Pacific. The bombs of World War II did not kill the island, but rats almost did:

There were at least ten species of land crabs, including the world’s largest terrestrial invertebrate — the coconut crab, which can weigh 15 pounds and live as long as a human. The land crabs maintained the plant community by dispersing seeds, breaking down organic matter and mixing soils. Seabirds did the same by bringing marine nutrients to this otherwise sterile coral atoll.

Palmyra’s native ecosystem was recovering from the U.S. Navy’s construction of bunkers, buildings, roads, piers, fuel tanks, and ammo dumps. What it couldn’t recover from was the infestation of alien black rats, presumably stowaways on Navy ships.

The rats ate the seeds of Pisonia and three other rare tree species, shutting down reproduction. They ate the land crabs, chewed the heads off baby sea turtles, feasted on seabird eggs and hatchlings and all manner of terrestrial and intertidal invertebrates.

Thus did Palmyra become one of countless islands around the globe converted by alien invaders from diversity and beauty to sameness and sterility. Ninety percent of all archipelagos are infested with alien rodents.

But unlike dead organisms, dead ecosystems can be brought back to life. That has happened at Palmyra. The island, a national wildlife refuge since 2001, is jointly owned and managed by The Nature Conservancy (TNC) and the U.S. Fish and Wildlife Service (USFWS). In 2011, Island Conservation (a non-profit group specializing in removing alien invaders from islands) and the USFWS partnered with TNC to rid Palmyra of rats.

Before the 1980s rodent eradication on islands this complex was unthinkable. But brodifacoum changed that. Non-anticoagulant rodenticides failed because they were so fast-acting. Rats aren’t stupid. When they saw other rats convulse and die shortly after ingesting bait they learned to avoid it. What makes brodifacoum such an effective conservation tool is that it takes a few days to work, so rodents don’t learn to associate it with danger.

Read the whole thing and remember that rats, cats , feral pigs, and goats on islands have pushed more species to extinction in the last 400 years than anything else.

1 comment:

LRM said...

What a fantastic article. That fairy tern is now my desktop background. Thank you.