Island Conservation in California and Mexico
Improving the Ecosystem Health of Baja and California Islands
Jun 7, 2009
Along California and Mexico’s Baja peninsula, about one-third of nearly 300 islands face the same stewardship issue: how to stop rare or endemic plants and animals from being wiped out by introduced animals running rampant over a landscape where they don’t belong.
The Special Problem of Invasive Animals on Islands
Ecologists consider invasive species to be the second biggest threat to biodiversity worldwide, eclipsed only by habitat destruction. Invasive species are those that spread uncontrollably once introduced, on purpose or accidentally, to areas where they are not native.
The problem of introduced species is particularly egregious for islands because of the inability of native species to escape new predators or competitors. Islands harbor unique plant communities and vital breeding, nesting and loafing areas for many rare or endemic species of seabirds and marine mammals.
According to the World Conservation Union’s article “A Cooperative Initiative to Manage Threats of Alien Species to Island Biodiversity” (July 1, 2001), islands are “more vulnerable to invasions and more likely to suffer catastrophic loss of biodiversity as a result of invasions, but are also more likely to respond to successful eradication and border control methods.” No wonder, then, that while islands around the world harbor roughly 20% of the world’s species, they have one-half of all endangered species.
Extinctions and Solutions for California's and Mexico’s Island Species
Introduced species worldwide run the gamut from mammals to invertebrates to plants to fungi. California’s and mainland Mexico’s human population explosions of the past 30 years have inexorably led to more and more people using the Pacific islands, and with people have come their animals:
- Rats
- Cats
- Mice
- Rabbits
- Pigs
- Goats
- Burros
One such invasion sealed the fate of the Guadalupe Storm-petrel, a seabird that succumbed to extinction from goat-induced erosion and cat predation early in the 20th century. But while the problems are many, the opportunity for turnaround is great.
Many of the islands in both countries are under the protective jurisdiction of the government. In 1994, a network of conservationists formed the nonprofit Island Conservation, and in 1997, they fostered the formation of a sister organization in Mexico, the Grupo de Ecología y Conservación de Islas, A.C.
Formal government and philanthropic support for conserving islands has grown ever since, aiding the work of scientists trying to save Mexico’s natural resources. Enlisting the participation and support of local people ensures that reintroductions will not occur.
Removal of Island Invasives Works
The beauty of island exotics removal is that once an island is freed of introduced animals, the ecosystem can pretty much bounce back on its own — provided there are no other invasive animal or plant problems. As Jessica Leber points out in "Of Rabbits and Men" in Conservation Magazine's Journal Watch Online (Jan. 14, 2009), it is necessary for managers to think holistically when removing island invasives.
Managers of Australia’s uninhabited Macquarie Island made a $24 million mistake in 2000 when they removed the island’s cats prior to beginning rabbit control. The rabbit population has since increased by an order of magnitude, and Leber reports, “their exploding appetites have utterly destroyed the island’s vegetation.”
The successful removal of island invasive species by the government, nonprofits, and cooperating scientists is ensuring the health of California’s and Mexico’s Pacific islands. Nearly 40 restoration projects have been completed in the past 12 years. To protect their heritage, local people are supporting initiatives to remove animals that, in some cases, they themselves introduced. Native and endemic flora and fauna respond positively and often within one year.
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