Fifty years ago butterflies were far more common that they are today. At the El Segundo sand dunes, 7 of 31 native species which occurred then are now extirpated. Three species of Los Angeles vicinity are globally extinct, four more appear extirpated (extinct in the area, but occur elsewhere), and several more have substantially declined in numbers. The cause of these changes are not always clear, but the response of butterflies to change speaks for their usefulness as environmental indicators, or "canaries." Miners in earlier times took canaries into the mines as sensitive detectors of gas before levels toxic to humans were reached.

Butterfly losses are documented worldwide with the problems of Los Angeles shared with other metropolitan areas from Sapporo to Porto Alegre. The pattern of loss of diversity is not limited to butterflies, but is characteristic to all groups of living things from plants to the highest mammals. The effects are subtle, however, and go unnoticed to the untrained eye. Travel though any of the vast reforested areas of the world give an illusion of natural places that in reality are green deserts. In other habitats the expansion of introduced species profoundly modifies the composition of communities. The presence of many open landscapes masks the crisis of declining biodiversity.

Life on earth today is the result of 3.5 billion years of organic evolution, a process which not only produced a rich diversity of forms, but the system of interactions which provides for the existance of all life. Human socio-economic evolution, together with overpopulation, has upset natural relationships by overexploiting resources, by shifting species geographically, by land conversion, and by pollution. The consequent extinctions and changes in natural community composition are largely irreversible. Los Angeles and vicinity model all these events in a rapidly changing time-frame.

In addition to the extinct and extirpated species, thirteen others have decreasing populations. Natural sites are degraded and fragmented (El Segundo sand dunes, Palos Verdes peninsula, Baldwin hills, Santa Monica mountains), and several species are almost gone. A major purpose of this guide is to encourage gathering accurate information on declining species (indicated by * before the name in the list) in hope mitigation can be achieved.

In spite of knowledge on butterflies, information remains incomplete. Conservation will depend on complete data of each species biology so that appropriate management techniques may be deployed in time to save them. A sense of urgency is required because species do not usually approach extinction with advance warning. For example, Wright's checkerspot had a widespread distribution throughout southern California with some populations of 100,000 or more individuals. The last specimens were observed in 1986. Loss of the species was probably due to a combination of drought with habitat conservation and fragmentation. The flat grassland habitat of the species is a preferred development site for builders.

Between natural habitats being cut into smaller segments without providing corridors for movement, spreading of introduced plants that diminish native foodplants, pollution, and changes of other animal populations, the densities of native butterflies will continue declining to a point where either genetic inbreeding or climatic extremes will wipe species out, predictably starting with the most sensitive.

You can help halt these impending extinctions by any or all of the following:

• Join and support the Center for Conservation of Biodiversity/Lepidoptera Research Foundation.
• Join and support active conservation organizations as The Nature Conservancy, Sierra Club, California Native Plant Society and others.
• Volunteer to gather information for distribution surveys and population counts.
• Understand and become actively involved with land planning decisions in your locality.

There is only one California and extinction is forever and ever.