Life Histories of Cascadia Butterflies

Fieldwork

49 fieldwork The life histories of Cascadia butterflies are molded by the three geographic/ climatic habitat zones summarized above. Within these zones, up to five subzones add their influences to life history biology and ecology, creating characteristic butterfly faunas. Some of these faunas are imperfectly known and may contain further ecological subzones with “new” races, subspecies, or even species. Even in highly human-populated areas like the San Francisco Bay and Sacramento Valley, butterfly surveys/studies are lacking for some botanical/ecological zones (Shapiro and Manolis, 2007, p. 8). The thinly populated vastness of Cascadia is inevitably home to a good many butterfly surprises that await discovery. We strongly encourage the reader to explore undersurveyed areas for butterflies. Get off the beaten butterfly track. Many areas are pristine roadless wilderness and difficult to access, but some are very accessible but deemed nonattractive to butterflies as well as to people. Butterfly discoveries can still be made in wasteland and developed habitats. Fieldwork Finding butterfly eggs, larvae, or pupae in the wild can be exciting, enjoyable, and uniquely rewarding. Poets, historians, and scientists have written for centuries of the pleasure and fulfillment of watching butterflies glide and flit among wildflowers in beautiful summer meadows; we believe that the discovery and study of their immature stages takes us a step deeper into the appreciation of these interesting and beautiful insects. But finding eggs, larvae, and pupae is less a matter of chance or luck than of careful planning and research, together with solid basic knowledge. Whether the goal is to find eggs or larvae or to capture a gravid female to produce eggs, one’s success is greatly increased by knowing when and where to search, how to recognize prime habitat, and how to recognize the sought-after species. Being well prepared does not diminish the enjoyment of the search or the excitement of the find, and in fact makes the eventual discovery even more rewarding. In contrast, searching blindly for immature stages is often so unrewarding that some will find it difficult to maintain interest. We hope this chapter will encourage field observers to take a little time to plan ahead in ways that will increase not only success but also the enjoyment of this delightful natural experience. Preparation for Fieldwork: Preparation can greatly reduce wasted or unproductive field time. Searching for tiger swallowtail larvae in the early spring, or greater fritillary larvae in the summer, will be predictably unsuccessful, because these stages do not occur at such times. Tiger swallowtails overwinter as pupae, so their eggs are typically laid in late spring and their larvae develop in the summer. Greater fritillaries overwinter as unfed first instars, feeding and developing in the spring. Butterfly life histories are complex, further complicated by the fact that some species are double or triple brooded, repeating their life cycle multiple times each season. Choosing the best time to seek immature stages in the field is not as simple as consulting a cookbook of data. The best timing varies from year to year and with latitude and elevation, and populations of species often wax and wane in a cyclic manner. So preparation for fieldwork is an art as well as a science, a combination of judgment, experience, and knowledge, pieced together with various fragments of information like a challenging puzzle. Probably the single most important piece of knowledge for Cascadia is the overwintering stage of each species. In more southerly, warmer regions the overwintering stage is less important, but in the Pacific Northwest winter is a great obstacle that must be overcome by every butterfly species. During winter there is no nectar and no edible 50 life histories of cascadia butterflies larval host plant, and the cold weather does not permit flight. To survive, all butterflies must have an overwintering strategy, or they must leave the region by migrating south. Some butterflies overwinter as eggs, others as young, partly grown, or mature larvae, some as pupae, and some as adults. The window of opportunity for finding immature stages of any particular species is dependent on that species’ overwintering stage. The overwintering stage of each species is described in our accounts and in some instances differs from the stages described from other geographic areas. The flight period of each species is also important; this, together with the overwintering stage, provides important clues to when immature stages will be present. The adult flight period varies in different years; for example, an early spring usually results in early flight periods...