But even with this “simple” problem, it could take “decades and not years” to see results, Croll said.
He pointed to the example of Clipperton Island, a French territory in the Pacific. In a 1958 visit to the island, an ornithologist named Ken Stager found it had been taken over by feral pigs, which, much like rats, had preyed on seabird eggs and whittled Clipperton’s seabird population to around 1,000 individuals.
“Like every good biologist back in the ’50s, he had a gun with him,” Croll said. So he killed all 58 pigs on the island.
The transformation was striking, if not immediate. Within a decade, seabird numbers were in the thousands. And in 2003, scientists reported the presence of 25,000 brown boobies (Sula leucogaster) and 112,000 masked boobies (Sula dactylatra) living on the island.
The results of their survey demonstrates that, given enough time, bird colonies — and the nutrient-rich guano they bring with them — can come back.
In the case of Clipperton Island, “it took 50 years,” Croll said, “but it’s now the world’s second-largest brown booby colony and the world’s largest masked booby colony.”
Banner image of a booby chick on the nest, above a coral reef lagoon by Nick Graham/Lancaster University.
John Cannon is a Mongabay staff writer based in the Middle East. Find him on Twitter: @johnccannon
Editor’s note: John Cannon received a fellowship from Nature Research to attend ESOF18. Nature Research had no editorial control over the selection of this story or its content.
Citations
Bellard, C., Cassey, P., & Blackburn, T. M. (2016). Alien species as a driver of recent extinctions. Biology Letters, 12(2), 20150623.
Ehrhardt, J. P. (1971). Census of the birds of Clipperton Island, 1968. Condor, 73, 476–480.
Graham, N. A. J., Wilson, S. K., Carr, P., Hoey, A. S., Jennings, S., & MacNeil, M. A. (2018). Seabirds enhance coral reef productivity and functioning in the absence of invasive rats. Nature, 559(7713), 250.
Lorrain, A., Houlbrèque, F., Benzoni, F., Barjon, L., Tremblay-Boyer, L., Menkes, C., … & Verheyden, A. (2017). Seabirds supply nitrogen to reef-building corals on remote Pacific islets. Scientific Reports, 7(1), 3721.
Pitman, R. L., Ballance, L. T., & Bost, C. (2005). Clipperton Island: Pig sty, rat hole and booby prize. Marine Ornithology, 33, 193-194.
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