Learning Secrets of the Bay: Endangered Ridgway's Rails Released Into South San Diego Bay Marshland

Amelia, a captive-bred light-footed Ridgway's rail emerges from hiding at the Living Coast Discovery Center on San Diego Bay National Wildlife Refuge. Team Clapper Rail has bred and released 451 light-footed Ridgways rails since the program began in 2001. Credit: Rinus Baak/USFWS

By Jon Myatt
October 3, 2016

A team of biologists and volunteers released six endangered light-footed Ridgway’s rails on San Diego Bay National Wildlife Refuge last week.

The hen-sized birds were bred in captivity at the SeaWorld rail breeding facility  and are about two months old. On Tuesday under a sunny sky, when the team's lead biologist Dick Zembal gave the command to open the carriers, the birds burst out, heading straight for the marsh as wildlife biologists, including those with the U. S. Fish and Wildlife Service, and others who helped raise them, cheered them on.

In a flash, the birds quickly disappeared into the salt marsh.

For decades, Team Clapper Rail -- a partnership between the U.S. Fish and Wildlife Service, SeaWorld, the San Diego Zoo Safari Park, the U.S. Navy and others -- has been working to bring this secretive marsh bird species back from the brink.

Technology plays a role…

To improve their efforts, biologists need to know how the birds behave, where they go and how they interact in the marsh.

Today, the team monitors rails with satellite telemetry.

Five of the released birds were custom-fitted with harnesses bearing a transmitter that will send data using satellite technology. This information allows scientists and land managers to follow the movements of these endangered birds as they move about the restored wetlands, hunt for crabs, shellfish and insects, and raise their young.

A captive bred Ridgways rail being prepared for release at San Diego Bay National Wildlife Refuge. Credit: Lisa Cox/USFWS

It may sound simple, but there are challenges.

First, the birds are difficult to observe in the cordgrass vegetation. Second, they are small and the harnesses are somewhat bulky, making the back packs difficult to attach and secure. And when the tracking device eventually comes off when the bird dies, the tide action twice per day makes it difficult to retrieve them.

Despite these hurdles, the team is working to capture some of the first data regarding the rails' movement.

Learning their secrets...

There are a number of on-going studies underway to learn about the behavior of these small marsh birds.

Eamon Harrity documents the release of a juvenile related rail -- the Yuma rail -- on Sonny Bono - Salton Sea National Wildlife Refuge.  Harrity and his team of researchers are gathering data on 14 first year rails for his study.  Credit: Eamon Harrity/USFWS

Leading one of those studies is Eamon Harrity, a PhD candidate at the University of Idaho. He is also testing new, lighter equipment and harnessing techniques that he hopes will make it easier to understand  where the rails move.

Research scientist Eamon Harrity shows a tiny, solar-
powered transmitter and harness used for Yuma
rails in his study. Credit: Jon Myatt/USFWS

"There is little known about where rails disperse to, or if they leave the area as they mature," he said. "One of the questions we want to answer about their behavior is ‘do they migrate or are they permanent residents?’"

To answer this question, Harrity and his small team of graduate students have traveled to Sonny Bono-Salton Sea National Wildlife Refuge where another population of rails are resident, and are fitting young Yuma rails with satellite telemetry backpacks using their new, lighter weight harnesses.

His study will hopefully answer more than just the one question. In addition to learning how and where first year rails disperse, he hopes to validate the use of the lighter weight equipment.

The soft plastic cord looks like fishing line, but stretches and is more flexible than the Velco ribbon harnesses used currently. He hopes the lighter cord will hold up to the extreme conditions in the Salton Sea area.

And like the Ridgways rails released in San Diego, his team is currently tracking 14 rails with telemetry. Early next spring, he’ll compile the data, and hopefully bringing a clearer picture of the rail’s activities.

What Their Activity Tells Us

Despite what little is known today, it is a common belief that light-footed Ridgway’s rails spend their entire lives in one coastal marshland (like South San Diego Bay). But that hasn’t always been the case.

Before the species became endangered, the birds traveled to other marshes up and down the coast, and into the Salton Sea and Great Basin, intermingling with other rails. This strengthened their genetic diversity.

Watch the San Diego Union-Tribune video coverage
of the release here. Credit: San Diego UT

Today there are hundreds of acres of new habitat due to wetland restoration projects completed by the U.S. Fish and Wildlife Service, the State of California and our non-governmental partner organizations.

Hope for the future

The Service and its team of partners are focused on working toward a genetically strong population of light-footed Ridgway’s rails, said Brian Collins, a biologist and the refuge manager at San Diego Bay National Wildlife Refuge.

"The hope is to see the birds moving to neighboring wetlands," he said. "This would indicate a beginning of recovery for the species and a sign that we’re keeping our coastal ecosystems healthy."

He added that if the birds thrive in the habitat, it “will show us that the ecological systems are functioning properly and capable of supporting the wealth of fish and wildlife that also live in the area.”

When monitoring began in 1980, the population in coastal California was down to 200 breeding pairs. That number is now up to 656 pairs.

Next spring, there could be new sounds of rails pairing up in the restored marshes of the San Diego Bay National Wildlife Refuge.

 

Jon Myatt is the digital communications manager for the Pacific Southwest Region, located in Sacramento, Calif.