Rare Butterfly Returns To San Diego National Wildlife Refuge
Biologist John Martin surveyed a plateau on a mountainside at the San Diego National Wildlife Refugeon a recent spring morning. The landscape is covered with coastal sage scrub, once the dominant habitat in the Southern California region.
This green ribbon of natural habitat that wraps around Mount San Miguel is a sharp contrast to the urban environment that surrounds the refuge's 11,000 acres of protected lands.
Martin could see downtown San Diego from this hard-to-reach vantage spot, but that is not what he was there to look at.
"This open area that I'm sitting in is high-quality habitat for Quino checkerspot butterfly," Martin said.
The endangered Quino checkerspots are flying on the San Diego National Wildlife Refuge this spring for the first time in years.
Martin knelt in a patch of coastal sage scrub. The spaces between bigger plants were covered with algae, lichens and mosses which keep invasive weeds at bay.
"But allow this plant, this tiny little grass like plant — plantago erecta — to grow in profusion. And the caterpillars of the Quino checkerspot need this plant to survive," Martin said.
This habitat is considered prime territory for the Quino. In fact, the fragile butterfly lays eggs on or around plantago erecta, the scientific name for the California plantain, in the spring. The insect's eggs and the larvae spend most of their life on the plant, the ground or safely tucked in a web-like cocoon. Quinos have a specialized ability to hibernate when environmental conditions are not good.
"When they emerge from summer dormancy, when the winter rains come out, they cause this plant to emerge and start growing caterpillars," Martin said, "to emerge from dormancy and eat this, and grow and shed their skins, and grow some more until they're about three centimeters long."
Quino checkerspots used to be quite common
For about three weeks in the spring, Quinos transform into adult butterflies. That is when they breed and propagate the next generation.
Their black, brown and white colored wings used to be a common sight. Millions flew from the Santa Monica mountains to Baja California, but the population crashed in the mid-1970s. Quinos finally got endangered species protection in 1997.
Sprawling suburbs stole a lot of the butterfly's habitat.
Fire and drought also took a toll on an increasingly isolated species.
"It's kind of like a bouncing ball. This is a species that booms and busts," said Susan Wynn, a U.S. Fish and Wildlife Service biologist.
Wynn spent a lot of time and energy working to improve the butterfly's future.
"But each time the ball bounces it's not bouncing quite as high. And some of these sites, it's just bounced so low that they don't have that resiliency or that adjacent population to rebound from, so we're hoping to get the techniques sort of figured out so that when we need to give it a little boost — bounce the ball a little higher — we'll have that ability, that we'll have that in our toolbox," Wynn said.
Biologists spent two unsuccessful years trying to capture local female Quinos on the San Diego refuge. They had no luck.
"Yes, it was very concerning, but it was also reinforcing that we were on the right track, that this was something very important to do," Wynn said. "And, so last year we did end up going up to Riverside because they had populations that were big enough to collect from."
"They are right on track with the natural populations, as far as they are emerging the same week the natural populations are emerging." - Susan Wynn, U.S. Fish and Wildlife Service.
Those genetically similar butterflies were collected and brought to a tiny trailer on the San Diego Zoo's grounds. Located near the elephant exhibit, theButterfly Conservation Lab served as home for the first ever attempt to rear Quinos in the lab.
Entomologist Paige Howorth set up the program that ended up producing 1,513 larvae and caterpillars.
"So the adult females that we receive from the wild and we set them up in these enclosures with the host plant, and so this is what they'll lay their eggs on," Howorth said.
Zoo staff nurtured the adults, fed the butterflies Gatorade and collected the eggs they deposited. By last December, the first group of larvae was ready to be released on the refuge. The 742 larvae were still hibernating, and while that is uncommon for a butterfly, it is typical for Quinos.
"It is occurring at the same time that the host plant in the habitat is completely drying up and going away. So they just kind of shut everything down for several months — until the winter rains start again," Howorth said.
The larvae were released on the refuge inside modified brown Christmas tree bulbs. The hope was that they would wake up as winter rain fell.
In January, about 800 caterpillars joined the larvae released just a month earlier.
Biologist Wynn hoped the Quinos would take their cues from nature.
Quinos were flying in the wild for the first time in years
The butterflies got a huge boost from a wet winter, which allowed the plants they feed on to thrive, and the payoff for Susan Wynn and fellow biologist John Martin came this spring.
"There is one right there," Wynn whispered in hushed tones.
"We did it, John," she said as she clapped gently.
Martin answered the praise with a gentle laugh and then a reminder.
"We'll have done it next year. If we don't augment here next year, I don't know, we'll see," Martin said.
Wynn and Martin were delighted to see about 20 Quino's flying in the refuge on that recent spring morning. It raised hope that the extraordinary captive rearing program could have a lasting impact on the small population of remaining Quinos.
"It worked," Wynn said. "They are right on track with the natural populations as far as, they are emerging the same week the natural populations are emerging."
The U.S. Fish and Wildlife Service has enough money set aside to do two more years of the captive rearing and releasing.
Biologists are optimistic that effort will boost the local population on the San Diego National Wildlife Refuge so that the rare butterflies spread to nearby suitable habitat on the refuge.
Eventually, biologists would like to see a self-sustaining population that no longer needs a human assist.