“Something there is that doesn’t love a wall,” opens the Robert Frost poem “Mending Wall.” And I suspect that, aside from the poetic longing for human connection, the “something” may actually be introduced rodents on seabird breeding islands. Ever since the sea-going Polynesians unwittingly scattered rats all over the tiny islands of the remote Pacific, ground-nesting seabirds have hit by wave after wave of human-induced damage. After the Polynesians came Europeans with cats and dogs, and more rats. Then the Americans fortified many Pacific islands in response to the looming Japanese threat in the 1940s, and along came, yes, more rats. The population of Bonin Petrels, for instance, dropped from 500,000 down to only 5,000 after 1940 when the Americans arrived on Midway Atoll with their rats. The rodents make easy meals of the helpless, blobby seabird chicks, and BirdLife International reports that 75% of threatened, ocean-dwelling seabirds are affected by invasive nest-predators.
On small islands, it’s sometimes possible to exterminate the entire rodent population and restore the ecosystem to its prehistoric, seabird friendly state. But on a big island, say Oahu, for instance, total eradication just isn’t feasible. Enter a relatively simple and apparently very successful solution: a big, sturdy fence. On Ka’ena Point at the western end of Oahu, scientists exterminated all the rodents within the fenced area, and so far, it seems to be working, keeping even little baby mice from passing through.
A husband and wife team of biologists continue to monitor the population, and are hopeful for its continued success. The location of Ka’ena Point, only 30 miles from Honolulu, also provides unparalleled opportunities for people to observe the albatross colony and its comical denizens.
With the bewildering daily increase in scientific technical complexity, molecular pathways and sterile bench top cell cultures, ecology remains perhaps my favorite discipline, where sometimes, the solution is as simple as a really good fence across the rocks.