A Silver Lining for Rare Smith’s Blue Butterflies

To the keen observer, Smith’s blue butterflies can be seen fluttering the coastal dunes or perched upon buckwheat plants around Monterey Bay from the Salinas River National Wildlife Refuge where this photo was taken, southward to Sand City. Credit: Diane Kodama/USFWS

By Ventura FWO Staff
November 29, 2016

With a wingspan of only one inch, Smith’s blue butterflies are a challenge to spot with the naked eye.

Despite their small size and rarity, the attractive bright blue coloring of the males and bright orange and brown coloring of the females never fails to catch the attention of U.S. Fish and Wildlife Service senior fish and wildlife biologist Jacob Martin.

Martin, based in Santa Cruz., is a native Californian and works to help recover threatened and endangered wildlife.  He has studied the butterfly for more than 10 years.

“Much of my work involves thinking and writing about how human activities affect the Smith’s blue butterfly; it is always refreshing to get out and see them behaving naturally in relatively undisturbed habitat,” Martin says.

Over the past two years, Dr. Richard Arnold of Entomological Consulting Services Ltd, has trained Martin and other U.S. Fish and Wildlife Service staff in techniques to survey for the Smith’s blue butterfly. In addition to survey techniques, Arnold helped develop a protocol for long-term monitoring efforts at Salinas River National Wildlife Refuge, a safe haven for Smith’s blue butterflies and many other native plants and animals that live within the coastal dune ecosystem.

In 2015, biologists estimated 1,300 Smith’s blue butterflies at the refuge using the new survey techniques. Previous techniques involved capturing and marking individual butterflies, a time intensive effort.

Typical dune habitat of the Smith’s blue butterfly.
Credit: Courtesy photo by Jared Klien

Now, biologists have established permanent sampling transects through the Smith’s blue butterfly habitat at the refuge. Biologists walk the transects twice per week throughout the season when adult butterflies are present, which runs between June and September.

“We identify each butterfly by species and sex, and record its location and behavior along each transect. Using spatial-statistical modeling techniques developed by Dr. Arnold, we are able to use the data to generate an estimate of the number of Smith’s blue butterflies within each acre of transect,” Martin said. Biologists then multiply this per-acre estimate by the 11 acres of habitat at the refuge to estimate the total number of adult butterflies present.

“The ability to calculate population estimates every year is invaluable in helping us track butterfly population trends over time,” says refuge manager Diane Kodama. “This information will guide our management priorities and track the success of our coastal dune restoration efforts.”

To the keen observer, Smith’s blue butterflies can be seen fluttering the coastal dunes or perched upon buckwheat plants around Monterey Bay from the Salinas River National Wildlife Refuge southward to Sand City. Within scrub, chaparral, and grassland plant communities, the butterflies can be seen from Carmel Valley to Big Sur, and northern San Luis Obispo County. These two areas, the Monterey Bay area and northern San Luis Obispo County, are the only two places where the rare blue butterfly is known to exist.

Listed as a federally endangered species by the U.S. Fish and Wildlife Service in 1976, the Smith’s blue butterfly has struggled to survive against trampling by humans and vehicles, proliferation of weeds, and coastal development.

Martin says that while development is not as much of a concern in the areas around Big Sur, because much of the habitat there is on Federal and State-owned land, fires are of great concern. Most recently, the Soberanes Fire burned more than 130,000 acres, including portions of the Los Padres National Forest along the Big Sur coastline. Some of that acreage burned included significant habitat of the Smith’s blue butterfly.

A brightly colored female Smith's blue butterfly at Salinas River National Wildlife Refuge. Credit: Diane Kodama/USFWS

“It remains to be seen how much of their habitat has been or will be impacted by the fire,” said Martin.

Progress has been made to help preserve coastal dunes and other key habitats that are vital to the species’ survival.

The U.S. Fish and Wildlife Service, California State Parks,Monterey Peninsula Regional Parks, Big Sur Land Trust, The Nature Conservancy, U.S. Army, and U.S. Forest Service have collaborated to manage important butterfly habitat on their lands and permanently protect habitat from future development in some areas.

However, additional proposed development on non-protected lands continue to threaten coastal dune habitats and the species they support like the Smith’s blue butterfly, the federally threatened Monterey spineflower and the federally threatened Western snowy plover. The data collected over time from the annual seasonal surveys at Salinas River National Wildlife Refuge will help inform how land managers can work to restore habitat to support the Smith’s blue butterfly population both at the refuge and in other areas where the species exists along California’s central coast.

“By tracking the status of the species at the refuge over time, the collected data could reveal population-level effects of management actions, and in turn inform how we approach habitat restoration in the future,” Martin said.