Butterfly biosensors offer habitat hints.

Butterfly biosensors offer habitat hints

Tropical butterflies, already valued for their beauty and grace, show promise as ecological workhorses in the emerging field of biodiversity conservation, preliminary research suggests.

The goal -- to use butterflies and other selected invertebrates as indicators of environmental health -- remains years from attainment. But ecologists have provided a strong theoretical basis for using these sensitive species in making land-management decisions. And now, some of the first experiments designed to test this approach appear to verify that butterflies can serve as environmental "markers" for a host of variations within their local ecosystems.

So-called indicator groups have long been popular among scientists concerned with pollution-related issues. Like canaries in a coal mine, these species -- if chosen correctly -- provide early warnings of subtle but significant environmental changes.

Conservationists now seek to identify a few key species that might do for biodiversity what previous indicator groups have done for pollution control. Many insects have complex life cycles that include leaf-feeding caterpillar stages, pupal phases and adult stages requiring specific interactions with flowering plants. This leads some ecologists to suggest that such creatures may prove ideal indicators of local environmental stability and plant diversity.

Claire Kremen, a conservationist with the Xerces Society in Portland, Ore., mapped butterfly distributions in various terrains within the southeast rain forest of Madagascar. Using two different computer programs designed to detect correlations between local conditions and species distributions, she identified an array of butterfly species that appear useful as indicators of subtle habitat differences there. Butterfly data from environmental "edges," where forest preserves border agricultural plots, may someday help planners decide what kinds of land use to permit alongside protected areas, Kremen says. She described her study this week in Snowbird, Utah, at the annual meeting of the Ecological Society of America.

Ecologists hope to identify other animal species -- ranging from soil-dwelling organisms to small vertebrates -- as biodiversity indicators in other environs, adds herpetologist Peter B. Pearman of Duke University in Durham, N.C. Some frogs may prove useful, he says, because of their need for both aquatic and terrestrial habitats.