Biologists Release Endangered California Butterfly Larvae into Native Habitat

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First Release of Quino Checkerspot Butterfly Gives Species a Second Chance for Survival

SPRING VALLEY, Calif.—A team of biologists from the San Diego Zoo, the U.S. Fish and Wildlife Service (USFWS), and the Conservation Biology Institute released 742 larvae of the critically endangered Quino checkerspot butterfly (Euphydryas editha quino) within its native range in the San Diego National Wildlife Refuge. This is the first-ever captive-rearing and release attempt for this California native butterfly species, whose population has been in drastic decline over the last decade.

The larvae—each measuring 4 to 6 millimeters—were propagated in the San Diego Zoo’s Butterfly Conservation Lab, where Zoo entomologists care for Quino checkerspot butterfly eggs, larvae and adults as part of the breeding program for this endangered species. The Butterfly Conservation Lab is funded by a USFWS Cooperative Recovery Initiative grant. The long-term goal of the grant is to help this butterfly’s population recover sufficiently to downlist the Quino Checkerspot butterfly from the endangered species list.

Biologists Release Endangered California Butterfly Larvae into Native Habitat

“Humans have had a significant impact on the decline of the Quino checkerspot butterfly—not only as the direct result of habitat loss due to development, but also as a consequence of climate change,” said Paige Howorth, associate curator of invertebrates, San Diego Zoo Global. “Humans are also playing a critical role in their recovery and today’s release is an important first step in fulfilling our responsibility to these graceful pollinators that also call San Diego County home.”

Since July 2016, the larvae have been in a period of dormancy, called diapause. This is a natural condition that coincides with the seasonal absence of their host plant, dwarf plantain (Plantago erecta). During this time, the larvae retreat into silk shelters and cease all activity.

To prepare for releasing these animals in this life stage, Zoo and USFWS staff collaborated to create a release pod that would provide safety for the larvae, protect them from predators and allow them to leave when environmental cues signal them to “break” diapause and begin feeding again. Staff settled on using a spherical mesh seed feeder, with a peat moss container inside, wired shut to provide additional protection. The orbs were painted to blend into the environment, and are capped off with a plastic “rain jacket” to make sure the peat moss container and larvae don’t get too wet. Each release pod is designed to hold several larvae—ranging from 15 to 28 individuals—and they are grouped with other larvae from the same clutch of eggs laid by an adult female Quino checkerspot butterfly.

Biologists Release Endangered California Butterfly Larvae into Native Habitat

The 38 pods were wired to native shrubs in the San Diego National Wildlife Refuge, in an area where USFWS biologists have observed strong growth of dwarf plantain. Biologists will be checking on the pods and looking for signs of caterpillars once a week, starting next week.

“This is the first time we’ve attempted to release Quino checkerspot butterfly larvae, and we expect to learn a lot from our work here today,” said John Martin, biologist, San Diego National Wildlife Refuge. “It’s important to help the Quino maintain its home range, in order to ensure survival of the species, and we hope they will thrive here and disperse to nearby suitable areas of the refuge.”

Biologists Release Endangered California Butterfly Larvae into Native Habitat

The Quino checkerspot was once among the most commonly seen butterflies in Southern California, ranging along the coast—from just south of Ventura County to the inland valleys south of the Tehachapi Mountains and into northern Baja California. In recent years, this species has experienced a drastic decline, primarily due to the loss of its habitat from increased urban development. Climate change, drought, invasive plants and fire pose additional threats to the Quino checkerspot butterfly, and its future has been uncertain. They are important to their environment as pollinators for native plant species.

After this winter’s rains, the larvae in the release pods are expected to emerge from diapause and begin feeding on the dwarf plantain that grows in the refuge. If all goes well, the released Quino checkerspot larvae should complete their development into adult butterflies from February to April 2017.

An adult Quino checkerspot butterfly has a 1.2- to 2-inch wingspan, and adults will be in flight in the area over a period of five to eight weeks. During this time, Quino males will patrol and establish territories, in order to win mates and start a new generation of butterflies. The USFWS will be working with researchers from the Conservation Biology Institute and San Diego State University, who will monitor the larvae and their development into adults.

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