Rare butterfly reintroduced on San Diego NWR

The recovery of an endangered butterfly in southern San Diego made history last year and is seeing early success.

A team of biologists from the San Diego Zoo Global, the Service, San Diego State University and the Conservation Biology Institute released 742 larvae of the endangered Quino checkerspot butterfly onto San Diego National Wildlife Refuge last December, the first release of captive-reared Quino larvae.

In January, 771 more larvae were released, bringing the total to 1,513.

The Quino population drastically declined over the last decade, and losing the native pollinator could hurt the coastal sage scrub ecosystems there.

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

Refuge manager Jill Terp and zoo keeper Brandon Rowley prepare protective pods for the larvae’s arrival onto the refuge. ©Lisa Cox/USFWS

To save the butterfly, the team raised larvae in captivity in the San Diego Zoo’s Butterfly Conservation Lab, where zoo entomologists cared for the eggs, larvae and adults. The lab is funded by a Service Cooperative Recovery Initiative grant, which supports projects to help recover some of the nation’s most at-risk species on or near national wildlife refuges, and mitigation funds from CalTrans. The long-term goal of the grant is to help the Quino checkerspot butterfly’s population recover sufficiently to down-list it from the endangered species list.

“Quino checkerspots have been reared in captivity in the past, but this is the first time that captive-reared Quino have been returned to the wild to augment wild populations,” Martin says.

A member of the brushfoot family, the black, white and orange-checkered 1.2-inch butterfly was once commonly seen south of Ventura County, ranging to the inland valleys south of the Tehachapi Mountains and into northern Baja California. The last time Martin spotted one on San Diego Refuge was in 2012.

The butterfly’s rarity presented a challenge: how to capture enough butterflies to start the breeding program.

Since the Quino’s population was too low to gather adult butterflies from San Diego County, biologists had to resort to collecting them from the Riverside population, about 60 miles northeast of San Diego.

“The genetic work we’ve done indicates that Quino populations throughout their entire range are basically the same,” says Susan Wynn, a biologist with the Carlsbad Fish and Wildlife Office. “Although these populations are widely separated geographically, they are genetically similar and should have similar biological needs. So we think they should do quite well.”

In recent years, the species’ drastic decline was primarily due to the loss of its habitat from increased urban development. Climate change, drought, pollution, invasive plants and fire pose additional threats to the butterfly.

“Humans have had a significant impact on the decline of the Quino checkerspot butterfly,” says Paige Howorth, associate curator of invertebrates at the San Diego Zoo Global. “But humans are also playing a critical role in their recovery and today’s release is an important first step in doing that.”

At the zoo last summer, the new larvae from the captured butterflies entered a period of dormancy, called diapause. This is a natural condition that coincides with the lack of availability of their host plant, dwarf plantain. During this time, the larvae retreat into silken webs and cease all activity. The biologists released them to the wild in this condition.

Beginning in February, biologists started checking the pods once a week, looking for signs of success. In early March, Martin counted 20-30 butterflies on the refuge in one day.

It’s still early, but not bad for a first try.

The U.S. Fish & Wildlife Service is a Strategic Partner of TWS.