Island Biodiversity
Milford Sound, New Zealand. Photo by Dov Sax.
DB: This is Earth and Sky. Scientists believe the total variety of life on planet Earth has been shrinking at an alarming rate.
JB: It’s possible that over 11 thousand species of plants and animals are in danger of extinction today. And some of the most severe losses are on islands in the world’s oceans.
DB: Yet, at the same time, more non-native species are becoming naturalized on islands. Dov Sax is an ecologist at the University of California in Santa Barbara. He and his colleagues studied extinctions and introductions of land birds and plants on over a dozen islands. They used historical and fossil records to determine that, on these islands, the number of bird species lost is roughly equal to the number that’s arrived to stay.
JB: So the total number of bird species on the islands has remained constant. In contrast, because there’ve been few plant extinctions and many plant naturalizations, the number of plant species has actually doubled. Overall, biodiversity – on some islands – is increasing.
Dov Sax: So this work presents a situation that really demands attention. And, I think that’s often the way science works. You answer one question and discover a hundred more.
DB: More tomorrow. Thanks today to the U.S. Forest Service and the National Fish and Wildlife Foundation – supporting the conservation of native fish, wildlife, plants and their habitats. We’re Block and Byrd for Earth and Sky.
The following person was interviewed for today’s program. Our thanks to:
Dov F. Sax, Ph.D.
Department of Ecology, Evolution & Marine Biology
University of California
Santa Barbara, CA
Links
Issues in Ecology (Issue #4, European Space Agency)
Books and Articles
Christopher Flavin, et.al., “Watching Birds Disappear,” in Worldwatch Institute, State of the World 2003 (New York: W. W. Norton, 2003), p. 8, 15
Wilson, E. O. 1987. The little things that run the world: The importance and conservation of invertebrates. Conservation Biology 1:344-346.
Additional Teacher Resources
Catalina Island Conservancy: Non-Native Animals
The presence of non-native animals on Santa Catalina Island is one of the Catalina Island Conservancys principal management challenges. Non-native animals are those that would not be on the island without the direct or indirect help of humans. This site explains the ecological effects of a variety of non-native species that now exist on the Catalina Islands as well as invasive plant species, conservation actions underway, and the ecological processes now in place on the islands.
U.S. National Park Service, San Juan Island National Historical Park: Nature & Science; Non-Native Species
This site is a good resource for introducing the concept of non-native species and the ecological impact they have on an island ecosystem. The site provides a broad overview of non-native island species, as well as a natural history of the species on the San Juan Islands.
Convention on Biological Diversity, Secretariat of the Convention on Biological Diversity; United Nations Environment Project (UNEP): Island Biodiversity Introduction
This site discusses the immense number of endemic species that inhabit islands systems around the globe and the potential problems that the introduction of non-native species poses to these systems. Also covered is factors and strategies in reducing the ecological vulnerability of islands.
Pacific Regional Environment Programme: Invasive Alien Species: Biggest Threat to Pacific Biodiversity
This site explores the effect of invasive species on island systems in the Pacific Ocean. It covers what an invasive species is, the effects of invasive species, how did they get there, and what we can do about them. The site also provides a variety of links to more information.
