March 31, 2017 – You can’t blame Diane Kodama, manager of the Ellicott Slough National Wildlife Refuge, south of San Francisco, for having a strong connection to Santa Cruz long-toed salamanders, given how much effort she and her colleagues have put into helping the endangered amphibians survive the historic drought that plagued California the last several years.
When they undertook a delicate, first-of-its-kind captive rearing of the salamanders two years ago, Kodama and her team didn’t know whether the young creatures would even survive the first few days, much less after they released them into the wild.
So it was a tremendous relief when mature salamanders were spotted in the area last November.
But in a surprising twist, at least some of them appeared to have returned not to Buena Vista Pond, where they historically breed, but to the site just up the hill where they were reared in plastic tubs almost two years before.
Through a process biologists don’t yet understand—magnetic geo-positioning, navigation by stars or perhaps tracking of site odors—some of the salamanders seem to have been imprinted with the location of the rearing tubs as they grew from finned larvae to legged metamorphs.
“We are fairly certain the returning ones are the rescue-reared salamanders, given their age and unprecedented numbers,” Kodama says.
The mature salamanders’ appearance at the captive breeding site was a wrinkle in the normal lifecycle, necessitating relocation to their original breeding pond. Typically, the larvae hatch from eggs in marshy ponds, sprout legs and migrate upland to underground burrow habitat, then return to the same ponds as mature adults to court and lay eggs on stalks of submerged vegetation.
The drought that began in 2011 shrunk Buena Vista Pond and threatened to wipe out the salamanders that breed there. So in 2014, Kodama, refuge biologist Chris Caris and their partners at the U.S. Fish and Wildlife Service’s Ventura office, California Department of Fish and Wildlife and Santa Cruz County’s Resource Conservation District made the decision to rehabilitate the pond, lining it with clay so that it would retain more rainwater.
The relined pond made a positive difference during the salamanders’ winter breeding season of 2014-15, capturing more of the minimal winter rainfall. Unfortunately, drought conditions persisted and something else had to be done. The team determined that it wouldn’t be feasible to artificially augment the water in the pond, given the pond’s location and the sheer quantity of water needed. Instead, they opted to begin the tricky task of rescue-rearing—a technique that had never been used for the endangered sub-species.
After a good deal of research—including consultations with fresh water aquarium experts and biologists experienced in captive rearing of other amphibian species—they made the decision to go ahead.
Still, Kodama says, “We were going in with a lot of unknowns.”
The idea was to capture larvae in the breeding pond through dip-netting and transfer them via small buckets to pond-like habitat created in 100-gallon tubs. It was a necessarily slow procedure to introduce the larvae to the water of their temporary homes, involving several hours of acclimatization before the buckets were submerged in the tubs and the larvae swam out.
YubaNet is powered by your subscription
Over the next several weeks, staff closely attended to the larvae, making sure frozen blood worms were eaten, testing water quality and monitoring for metamorphosis. In anticipation of legs sprouting, they added floating platforms to the tanks and gradually drew the water levels down. When the first legged metamorphs arrived, the biologists transferred them to tubs with most soil, wood cover objects and live food, to train for salamander life in the surrounding oak woodlands.
For Caris, the operation was a flashback to high school. “I was an aquarium nerd back then. But I never expected I’d be using that experience in my work at the refuge. “
He was excited about the rescue-rearing, but only cautiously hopeful.
“They were going to die if we didn’t do anything—that much we knew. We thought it would be worth it if we could save a dozen.”
Kodama describes her emotions during the rescue-rearing: “Every triumph you have—‘They’re eating worms!’ ‘They’re taking to the water!’ ‘They’re growing!’—you take pride in it.”
As it turned out, more than 300 young salamanders were successfully reared and released into the wild.
The local ecosystem stood to benefit from the successful rearing as well. The Santa Cruz long-toed salamanders exist nowhere on earth except a small range in neighboring Santa Cruz and Monterey counties. Among other critical roles they play in their native habitat is the consumption of mosquito larvae. As with other amphibians, their migration between water and land also makes them a good indicator of the health of the entire watershed in the area.
“Salamanders aren’t flashy,” Kodama says, “but they are critical to the ecosystem. If they’re doing well, the watershed is likely to be doing well. It can be frustrating when you see the threats from humans—the development and contamination, especially from pesticides.”
Caris echoes the point: “The health of the salamander is an indication of how much humans have altered the environment. I don’t believe we have the right to be responsible for the extinction of a species.”
The return of the rescue-reared salamanders shows that, sometimes, we can make a positive intervention, as well.