Watching Ridgway’s rails at Kendall-Frost Marsh

Watching Ridgway's rails at Kendall-Frost Marsh
Video cameras in Kendall-Frost Mission Bay Marsh Reserve’s raft shelters help biologist monitor endangered Ridgway’s rails and other wetland wildlife. Image: San Diego Audubon Society

By Karina Ornelas, ReWild Mission Bay

Kendall-Frost Mission Bay Marsh Reserve is the year-round home of Ridgway’s rail, a federally endangered species recently recognized as distinct from its relative the clapper rail. Three local organizations have been working together to monitor the rail and other wildlife that call Kendall-Frost Marsh home. They include the UC San Diego Natural Reserve System, San Diego Audubon Society, and Renascence Inc.—a nonprofit that reconnects Kumeyaay Native Americans to coastal lands.

Ridgway’s rail is especially interesting because the birds are seldom spotted in Kendall-Frost Marsh. They’re both very cryptic, and very rare. In its 1985 recovery plan for the rail, the US Fish and Wildlife Service states that the goal is to attain 800 breeding pairs in southern California.

Unfortunately, Kendall-Frost’s rail population has been trending downward. Past Ridgway’s rail surveys show that in 2015, there were 33 pairs at Kendall-Frost Marsh. In 2019, that number declined by 2 pairs. The 2023 southern California rail survey results have just been released, and finds that number is down to 10 pairs.

Watching Ridgway's rails at Kendall-Frost Marsh
Author Karina Ornelas holds a Ridgway’s rail. Image: Nancy Fernandez, U.S. Fish & Wildlife Service, San Diego National Wildlife Refuge Complex

Since May, we have installed four cameras in the marsh to monitor the behavior of the Ridgway’s rails and other wildlife. The cameras cover the interiors of the covered rafts that UCSD has been maintaining since the mid-1980s. These rafts, which consist of a platform, a frame anchoring it to the surface, and a dome-shaped protective cover, give the rails a safe and dry place to rest or nest during high tides. The rafts are essential because marsh vegetation, especially cordgrass, is no longer sufficiently tall or dense for the rails to find refuge from predators. The lack of vegetation also deprives the rails of a sturdy framework around which they would normally make their own floating nests.

On August 29, 2023, the U.S Fish and Wildlife Service, Living Coast Discovery Center, City of San Diego and San Diego Audubon released seven captive-bred and banded Ridgway’s rails from Living Coast Discovery Center at Kendall-Frost Marsh Reserve. These birds bolster the 10 pairs estimated from the 2023 survey. Since then, we have spotted four of the banded rails using three of the rafts. The birds apparently notice and respond to the camera. This video footage confirms that the four released birds are still in the marsh and adapting well to their new home. The cameras also give us a wealth of knowledge about rail behavior and raft usage that we didn’t have before.

Watching Ridgway's rails at Kendall-Frost Marsh
An analysis of what Ridgway’s rails do while inside the floating rafts of Kendall-Frost Marsh is based on video recordings of the birds. The birds usually lie down to rest.

Over the past few months, the cameras show that rails use the rafts to rest and eat when the tide is high. About 77% of the time, the rails use the rafts when the tide is 4–6 feet above mean lower low water, and mostly in the late afternoon.  From 3 pm to 9 pm, they may spend anywhere from 10 minutes to 4 hours inside lying down, looking for food, or resting while alert–indicating they consider the rafts nice places for them to rest.

Kendall-Frost is home to a lot of other wildlife, too. While monitoring the cameras we have seen crabs, raccoons, mice, spiders and insects, and Belding’s savannah sparrow, a bird listed as endangered by the state of California. This year, the cameras were not out early enough to observe nesting on the platforms; we saw nesting materials but not active nests. We plan to continue monitoring the platforms, and hope that next year to get some photos or videos of the rails with chicks. During the summer, biologists found three hatched rail eggs on one of the artificial platforms lacking a camera, so some new chicks should be living in the marsh. 

Watching Ridgway's rails at Kendall-Frost Marsh
A new coloring book shares Kumeyaay names for plants, animals, and waters found in Mission Bay. Image: San Diego Audubon Society

The rail has long been a part of the cultural history of Mission Bay. Kumeyaay-led Renascence Inc. recognizes this in its project to share Kumeyaay stories and their connection to the bay and wildlife. One aspect of the project is the creation of a coloring book, released this winter, depicting Mission Bay and Kendall-Frost Marsh wildlife through the eyes of animals. Giving coastal animals their own perspectives and voice is an important way of acknowledging their relationship to people, and is a perspective used in many Kumeyaay stories. The coloring book includes many words used by Kumeyaay people for animals and habitats in what we now call Mission Bay.

Another part of the project is to learn more about Kumeyaay song cycles and share knowledge. Partnering with Audubon CA, ReWild Mission Bay will work with Renascence and other Indigenous partners to create an ArcGIS StoryMap based on where the song takes place.

In the future, we are working hard to expand tidal wetland habitat at Kendall-Frost Marsh through the ReWild Mission Bay project. As the rail survey report has stated for many years, the species would benefit from the restoration of substantial wetland acreage in Mission Bay. Kendall-Frost Marsh is a tiny, remnant ecological memory of what Mission Bay used to be, but it has huge potential to help Ridgway’s rails recover in coastal San Diego. 

Learn how you can help restore the wetlands at Kendall-Frost Mission Bay Marsh Reserve.

About the author

As Conservation Outreach Coordinator for ReWild Mission Bay, Karina Ornelas has been spearheading Ridgway’s rail monitoring in Kendall-Frost Marsh. She has been an advocate for ReWild since 2019, helping translate materials from English to Spanish to better connect with the Latino community. Karina is majoring in Conservation Biology and Ecology at Arizona State University.

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