Jaymee Marty handles a California tiger salamander trapped at Travis Air Force Base. Photo courtesy Marina Olson. BY JODI PETERSON
Why did the California tiger salamander cross the road? Most likely because it was migrating. Twice a year, these unusual amphibians travel between their breeding ponds and their burrows. Unfortunately, at Travis Air Force Base in central California, their route includes runways and streets. That puts the federally protected animals at risk—which could also put the military mission at risk.
That’s where Colorado State University’s Center for Environmental Management of Military Lands comes in. CEMML staff manage the California tiger salamander population at Travis AFB as part of a broad program to support the base’s natural resources and ensure compliance with federal and state environmental laws. Other biologists in the region also participate, volunteering their time to help monitor and relocate the salamanders. In return, they get credit toward the 20 hours of hands-on training required to obtain a federal recovery permit for working with this rare and sensitive species.
Although Travis AFB has been officially considered habitat for the California tiger salamander since 2004, when it was listed under the Endangered Species Act, the creature had been spotted at the base only a handful of times. “It was like this unicorn species,” said Jaymee Marty, CEMML cooperator and lead ecologist for the project. Then, in May of 2017, an especially wet year, airmen noticed dozens of young salamanders trying to cross the airfield. The United States Fish and Wildlife Service was quickly called in to evaluate the situation. An emergency protection plan required Travis AFB to monitor the animals, collect data about their populations, and map their migration corridors. That summer, more than 600 juveniles were trapped and safely relocated away from the airfield.
Each year since, during migration season (early winter and early- to mid-summer), CEMML cooperators and staff have checked roads and runways for migrants and relocated them when necessary, trapped adult and juvenile salamanders to track their movements and population numbers, and surveyed breeding ponds. In 2023, biologists encountered a record number of California tiger salamanders at the base—more than 3,100. Of this total, less than 2% were killed, injured, or otherwise considered “take”, indicating that current management actions are working. The low “take” number meant that the base’s activities didn’t have to be restricted to protect the salamander, which is important because Travis AFB is a critical logistics hub for the Air Force.
California tiger salamanders are stocky and grow seven to eight inches long; have a broad, rounded snout with a perpetual “smile”; and boast striking white or yellow markings against black skin, with a pale belly. They breed in ponds and live in upland grassy areas, where they occupy rodent burrows. Their larvae spend several months growing in the breeding pond, then develop legs and a tail so they can migrate through upland habitats to find burrows. After several years, they will migrate back to the pond where they were hatched to breed.
Like many wildlife species, the California tiger salamander tends to have “boom or bust” cycles. “We were trying to figure out if we could predict which years we would have a lot of salamanders coming out of the pond and which years we would have fewer,” said Marty. “We’ve been able to forecast pretty accurately, based on the hydrology of the breeding pond, whether we’ll have 100 salamanders or 3,000. And that helps the Air Force to plan better.” In contrast to 2023’s bumper crop, in 2024 the main breeding pond dried up quickly and is producing very few juvenile salamanders. “It’s nothing to do with how the pond is managed,” said Matt Ley, the principal investigator who oversees CEMML’s natural resource management support at Travis. “It just depends on how much rain Mother Nature sends us.”
So far, the most effective approach to protecting migrating salamanders at Travis also takes the most hands-on effort. “We’ve shown that we can reduce mortality by assisting them across, trapping them on one side of the airfield and moving them to the other side,” said Marty. Since 2017, biologists at the base have trapped and relocated more than 5,000 salamanders.
It’s not clear yet what the best long-term solution is. CEMML is working with an engineering firm to determine the feasibility of various approaches such as constructing tunnels under runways or building barriers to direct the salamanders away from the airfield. Whatever solution is chosen, the efforts at Travis will continue to meet the needs of both the Air Force and wildlife. “It’s a win-win-win,” said Ley. “We’re training other biologists so they can support the California tiger salamander on a regional scale, and their volunteer efforts let us work more quickly and efficiently. And we’re protecting this imperiled species on the base while ensuring the military mission can continue unimpeded.”