Can the native species of the ecological treasure that is the Galapagos really be protected from invasive species?
Laura Santoso of the California Institute of Technology takes a thoughtful, in-depth look at the issues and conflicting interests in Wired Science:
Even with unlimited cash, it seems impossible to eradicate certain intruders without also harming native species. Small but pervasive species, like rats, are extremely difficult to target without catching resident wildlife in the crossfire. In 2012, 22 tons of rat bait were dropped by helicopter on Pinzon island, blanketing 7 square miles with little blue poisonous cubes. Several organizations, including the Galapagos National Park and CDF, supported the move because the rats had been devouring the eggs of native giant tortoises and lava lizards. But the “raticide” sparked significant controversy, imperiling neighboring native species like the Galapagos hawks. While pesticides are often the best available option (biological interventions are technically challenging to develop), they cannot suppress invasive species without causing side effects.
The final piece of the puzzle, after thwarting new invasive species and removing existing ones, is actively helping endemic species recover. Some local fauna, like the tortoise and the mangrove finch, have been so decimated that they may be destined for extinction without significant help. On the other hand, Giant Tortoise rehabilitation is one example of seemingly productive human intervention. When tortoise populations had dwindled from thousands to dozens on some islands in the 1960s, they were taken in by humans and bred in captivity. Repatriation projects on Santa Cruz, Isabela, and Espanola have increased total tortoise populations to 26,000, but the current dependence on human assistance sparks questions about whether the intervention itself is unnatural, or unsustainable. Although the repatriated tortoises have begun to mate by themselves in the wild, it is unclear if they can maintain their numbers once captive breeding stops.
Photo: kingsnake.com user Ivory Tortoise …read more
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