The Fender’s Blue butterfly and Kincaid’s lupine
Tucked between the agriculture fields of Oregon’s Willamette Valley are small pockets of native grasslands, remnants of an upland prairie ecosystem that once dominated the landscape. Within these islands of habitat one may discover the Fender’s blue butterfly (Icarius icariodes fenderi) and Kincaid’s lupine (lupinus sulphureus kincaidii), two species which are known from only a few locations. The Fender’s blue butterfly and Kincaid’s lupine are closely associated, with the butterfly relying upon the lupine as a food source during its caterpillar stage. Due to expanding human use of upland prairie, these species are faced with extinction and may be lost unless their remaining habitat is conserved.
The Fender’s blue butterfly and Kincaid’s lupine are inhabitants of native upland prairie in Oregon and southern Washington. Botanically diverse, native upland prairies are typified by the presence of fescue bunchgrasses (Festuca rubra or Festuca idahoensis), with other herbaceous perennials such as Toimei’s mariposa (Calochortus tolmei). Hooker’s catchfly (Silene hookeri) and broad petal strawberry (Fragaria virginiana) interspersed throughout. These dry, fescue prairies once covered an estimated 685,000 acres in the Willamette Valley. Now, less than 1,000 acres remain. As this habitat declines, so do associated plant and animal species. Prairie sunflowers such as balsam root (Balsamoriza deltoidea) and mule’s ears (Wyethia angustifolium) are members of this vanishing community, as are important insect pollinators such as solitary Anthophorinid bees.
The Fender’s blue butterfly was first described in 1929, from collections by R.C. Macy. Following the completion of Macy’s studies in 1937, the butterfly was not reported again and was presumed extinct. In 1989, lepidopterist Dr. Paul Hammond rediscovered the Fender’s blue butterfly while exploring lupine patches in Benton County. At this point the butterfly’s close association with Kincaid’s lupine was noted. With this information, other Fender’s blue populations were successfully located. Currently, the butterfly is known from twelve sites, several of which are on the verge of collapse.
The life cycle of a Fender’s blue butterfly begins in early summer, with an adult female depositing an egg on the underside of a Kincaid’s lupine leaflet. Eleven to twenty days later, the egg hatches and a tiny first instar larva emerges. The larva feeds on lupine leaves and may pass through one or two molts before the plant upon which it is feeding begins to senesce. At this point, in mid-June to mid-July, the young larva drops to the ground and enters an extended diapause, or state of hibernation. Fall and winter pass, and the larva breaks diapause in March or early April. As Kincaid’s lupine emerges from its own winter dormancy, the Fender’s blue larva feeds on fresh developing leaflets. The larva molts three to four additional times as it grows and prepares for metamorphosis. Metamorphosis into adult form begins with pupation, a two to three week state during which the larva’s body is reorganized into the form of an adult butterfly. A Fender’s blue butterfly emerges from its pupa state in May and begins the cycle again.
Male Fender’s blue butterflies are silvery-blue on the upper wing surface and gray on the underside. The underside often has a series of small, black spots near the hindwing edge. Female butterflies are quite different in color, showing a brown upper wing surface with an underside similar to that of the male. The butterflies are small, with a wingspread of only 25mm (1 inch).
Kincaid’s lupine is easily distinguished from other species of lupine due to its low-growing habitat and unbranched flower stalk. Its aromatic flowers have a slightly reflexed, distinctly ruffled banner and are yellowish-cream colored, often showing shades of blue on the keel. The plant’s leaflets tend to a deep green with an upper surface that is often smooth. The plants are low-growing 16 – 30 inches, with flowering stems which exceed the height of the branched crown.
Reasons for Decline
The ecological conditions that allowed native upland prairies to flourish in the Willamette Valley are the same that have allowed for the successful expansion of agriculture. Consequently, few natural sites remain which have not been converted to managed uses. Even small, formerly ignored sites such as fence rows and roadsides are disappearing as private lands come under increased pressure to produce revenue for owners.
In the limited number of sites which have been left undeveloped, other forces have reduced both the quantity and quality of remaining habitat. Grasslands by nature are a transient community which require infrequent, periodic disturbance to prevent transition to forest. Tree and shrub species invade undisturbed grasslands over time, shading out low-growing species such as Kincaid’s lupine. In addition, non-native species such as Himalayan blackberrry (Rubus discolor) aggressively overtakes open spaces and crowd out native species.
Loss of native upland prairie results in the separation of butterfly and lupine populations which were once inter-connected. As the number of sites declines and the distance between them increases, the opportunities for movement of seed (in the case of the lupine) and adults (in the case of the butterfly) between populations is reduced. Populations become isolated and face a higher chance of failing, since they are no longer a part of a larger, more stable system. As populations fall, the total number of individuals remaining gradually falls, and the probability of extinction for the species as a whole becomes much higher.
Reasons for Concern
Were the Fender’s blue and Kincaid’s lupine to go extinct, few would likely notice. But the disappearance of these species would carry with it the loss of a community which contributes directly to our quality of life. Beyond their aesthetic value, biologically diverse natural landscapes play a role in harboring predatory invertebrates which keep pest insects at bay. In addition, native grasslands provide food and shelter for more visible mammals and birds which have direct value to us.
Natural processes which functioned to maintain open meadows have been altered to the point that intervention is needed to prevent further loss. Historically, large-scale fire played a role in maintaining grasslands in an open state. Today, grasslands remnants are no longer maintained by fire due to suppression efforts. Where possible, controlled burning is substituted as a tool for managing grassland ecosystems. Alternatively, conservation efforts focus on careful mowing and hand-clearing to discourage the growth of invasive non-native and woody species.
Habitat management and conservation efforts have thus far involved the cooperative efforts of public and private parties including the Army Corps of Engineers, the Oregon Dept. of Agriculture, the Oregon dept. of Fish and wildlife, the Oregon Natural Heritage Program, The Nature Conservancy and the U.S. Fish and Wildlife Service. Only through the continued work of these parties and THE ASSISTANCE OF PRIVATE LANDOWNERS can the survival of these rare species be assured.