Ecology and conservation of the Fender's blue butterfly.

摘要

Insect populations are declining around the world, primarily due habitat loss, fragmentation and degradation. I address challenges to insect conservation, in general, and to designing conservation strategies for an endangered butterfly, in particular. These studies suggest avenues to recovery for rare insect species.; First, I explore challenges in insect conservation. These concerns stem from lack knowledge about basic biology, widely fluctuating population sizes, fragmentation-induced isolation, difficulty in addressing problems at the right scale and managing in "semi-natural" habitats.; Second, I investigate several of these challenges in the context of the Fender's blue butterfly, (Icaricia icarioides fenderi), a species proposed to be listed as "endangered" under the U.S. Endangered Species Act. I describe several observations and experiments designed to fill gaps in our knowledge of the basic demography and natural history of the Fender's blue.; Next, I pursue two detailed investigations that look at implications of Fender's blue biology for conservation strategies. In the first study, I use a combination of a field and quantitative approaches to ask how to design reserves for Fender's blue. I conclude that stepping stones, not corridors, are a better method to reduce fragmentation-induced isolation because the butterfly's dispersal behavior is not strictly tied to its preferred habitat. In the second study, I look at the role of limited food resources in limiting butterfly population size. I conclude that supply of both larval hostplants and adult nectar sources limits Fender's blue populations.; Finally, I look at implications of butterfly demography for prioritizing management strategies that use fire to reduce weeds. Based on experiments from 1994 to 1997, I know that fire kills butterfly larvae but enhances butterfly habitat and augments female fecundity. Given this tradeoff, I investigate the potential of a range of management strategies to maximize butterfly persistence. I vary the fraction of habitat that gets burned in each fire and the frequency with which fires are set to conclude that, on average, burning 1/3 of the habitat every year is the best strategy, but that several other strategies suggest a {dollar}<{dollar}95% probability that the population persists for 100 years.