Bringing Back the Ridgway’s Rail-and its Habitat
Call someone “thin as a rail” and what are you really saying? Thin as a bed rail? As a train rail? A chair rail? None of the above, actually. The phrase refers to a family of birds called “rails” that tend to frequent marshes.
One rail local to San Diego County has gained modest renown in the past few years. In 2014, based on genetic research, three West Coast Clapper Rail subspecies found themselves in an entirely new species (Ridgway’s Railor Rallus obsoletus).The nominate California Ridgway’s Rail (R. o. obsoletus) lives in coastal marshes of the San Francisco Bay area; the Yuma Ridgway’s Rail (R. o. yumanensis),in the lower Colorado River area, with significant populations inhabiting the freshwater marshes in and around the Salton Sea; and the Light-footed Ridgway’s Rail (R. o.levipes), in coastal salt marshes of southern California, including San Diego County. All three have the dubious distinction of being on the Federal Endangered Species List.
Two of the three subspecies of the Ridgway’s Rail—the Light-footed and California Ridgway’s Rail—don’t simply like salt marshes. They look for a very specific configuration of these marshes, namely edges where cordgrass meets mudflats or tidal sloughs. The third subspecies, the Yuma Ridgway’s Rail of the Salton Sea, is the only one to consistently inhabit freshwater or alkali marshes, with open water surrounded by cattails and bulrushes. In San Diego County, the Tijuana River Valley area hosts the largest population of Light-footed Ridgway’s Rails, although a few can be found at the Buena Vista Lagoon.
The Ridgway’s Rail’s common moniker “rail” arises from French rale (that language’s word for a rail). “Ridgway’s” honors Robert Ridgway, an ornithologist from the late 19th and early 20th century who served as the Curator of Birds at the Smithsonian Institution for more than four decades. In his long career, Ridgway described more new taxa of American birds—including the eponymous Ridgway’s Rail—than anyone else. Its genus name derives from medieval Latin term for a rail (rallus); the species name (obsoletus) sounds as if the endangered bird has already disappeared. But the root comes from Latin for “dull” or “plain,” referencing the rather drab feather pattern on the bird’s back.
A Ridgway’s Rail has a strangely shaped body, with a bulging breast and a rather saggy rear. If you catch a head-on view, though, you’ll see that the bird is laterally compressed—looking surprisingly thin, as if it had walked into a closing vice. (Hence the phrase “thin as a rail.) But having drab coloration and being thin offer evolutionary advantages. Both configurations make it easier for the bird to slip through dense vegetation without being seen or creating a noisy distraction. Ridgway’s Rails can produce large clutches (5-14 eggs) and can even raise a second brood after a successful first nesting. If things don’t go that well, pairs may renest up to five times following a series of nesting failures. Overall, nesting success can be high in high-quality habitats.
With all of these adaptations, why are these rails endangered? Ah, there’s the rub—high-quality habitat. Their preferred habitats—salt water and freshwater marshes—have been under attack by us humans for quite some time. Converting marshland to agricultural lands occurred commonly. Dikes built for flood protection further inland changed the nature of the marshes—sometimes as dramatically as from a salt water marsh to a freshwater marsh, such as at the Buena Vista Lagoon. Expanding cities targeted salt marshes for waste disposal sites. As salt water marshes have become more uncommon in Southern California, Light-footed Ridgway’s Rails have begun to use freshwater marshes, as do the Yuma Ridgway’s Rails. But freshwater marshes have faced similar threats including loss through channelization and dredging activities. Humans seemed to have declared war on marshes.
Beginning in the 1970s, though, we began to realize the value of those formerly disdained marshlands for flood control, for increased water quality, and as critical habitat for wildlife, to name just a few benefits. Efforts to protect, restore, and create marsh habitats are underway. Cooperative efforts between captive breeding programs (such as those at Sea World and the San Diego Zoo Safari Park) and sites with suitable habitat work together to kick-start the species’ recovery through releases of these rails into appropriate environments. In fact, 20 captive-raised rails have been released at our very own Buena Vista Lagoon since 2011.
To paraphrase Maya Angelou, we did then what we knew how to do. Now that we know better, we can do better—for marshes, for rails, for ourselves and our world.
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