Endangered Bird Gets a Home Away from Home

Photo Credit: USGS 

In some situations preserving the habitat of a species can be detrimental to the surrounding species. This is the case with the California clapper rail in the San Francisco Bay.

Clapper rails are chicken sized birds which rarely fly and the California clapper rail (Rail) is a subspecies that can only be found in the San Francisco Bay (Bay). With a compact body, strong legs and a short tail the Rail is a grayish brown colored shorebird with a pale chestnut colored breast, and white patch under the tail. It uses its long orange-brown bill to search for arthropods (creatures like snails, mollusks, etc. that they feed on) in the mudflats of tidal marshes. 

They’re pretty distinctive, but you’ve probably never seen one on your walks along the Bay. Although large for a shorebird, Rails are shy and tend to be heard and not seen. Their call is a short series of clacking or grunting notes. You can listen to the Rail’s call on the Cornell Lab of Ornithology website.  That way next time you’re on the Bay you know what to listen for.

The Rail’s endangered status has stemmed from issues of predators and loss of habitat as more and more marsh is developed into housing. A new threat to these birds is water level changes due to climate change. As the water rises, it threatens what little habitat remains for these rare birds. As if that wasn’t bad enough, the Rail has been struck hard in the last few years as conservation actions to help preserve the marsh plant diversity have had an unexpected and negative effect on the Rails. With the removal of invasive Spartina, a non-native plant, the Rails are losing yet another place to make their nests in and use as shelter from their predators.

Photo Credit: Andy Raabe USFWS

This non-native plant has invaded many marshes in the San Francisco Bay and is a threat to both the marshes themselves as well as the native plants that it has overrun. The threat of the invasive Spartina has led to Invasive Spartina Project and other organizations working to control the plant’s spread.

The answer seems simple, get rid of, or control, the invasive Spartina. It’s a danger to the ecosystem of the marsh, so take out the danger.

Well, it isn’t that simple.

The Rails have been using this non-native plant to hide during high tides. Without this plant the Rail becomes too exposed, and their species could slip even closer to extinction. Remember, this bird rarely flies and when it does it’s only for a short distance, so its best defense is having a place to hide. The Rails predators include stray cats in nearby neighborhoods, hawks and other raptors that perch on power lines, rats, and foxes. With only 8% of the San Francisco’s original marshland remaining, the Rails have very limited space to escape from the vast array of predators, which is where the Spartina comes in.

So how is the invasive plant controlled without threatening the entire population of the endangered Rail? As they lose places to nest in the invasive plants what will take its place?

The Invasive Spartina Project, the U.S. Geological Survey, the California Coastal Conservancy and the U.S. Fish and Wildlife Service are involved in a project that started in 2010 to create a safe place for the Rails to raise the next generation of chicks. A type of refugia habitat, these floating islands are only temporary but are being used to study the effects that the control of the invasive Spartina has on these birds. The thought is that the Rail can eventually use native plants to shield them from becoming prey; however these native plants need time to reclaim the marsh and grow. Thus the need for the temporary islands.

The floating islands are small, man-made islands made of recycled plastic bottles and/or Styrofoam that float on the water with changing tide levels. They support woven palm screens, similar to the what duck hunters use in duck blinds, which are attached to the top of the support poles. The islands are numbered according to their location in the marsh and monitored to track which species benefit from the islands.

Photo Credit: USGS 

So far monitoring has shown that Rails have been occupying all islands ranging from 190 to some that have around 12,000 Rail visits each within the months of October-December. Considering there are only about 1,500 of the Rails on the planet, that’s a huge rate of success.  The monitoring has also shown that the islands get the most use at high tides when the marsh is mostly flooded. 

The marsh habitat is just another example of how fragile ecosystems can truly be. The invasive Spartina needs to be controlled in order to allow native Spartina’s regrowth, however until the native plants come in the animals of the marsh are left with nowhere to escape from predators and raise their young.

No tall plants in a marsh is the equivalent of no walls in our cities. Take out one species, be it plant, animal or insect, and watch the building blocks of an ecosystem tumble down.

To ensure that the house is still standing for these rare creatures faced with a lack of natural cover has led to wide use of these artificial habitats - who knows, maybe they’ll even be beneficial to other marshland critters.

The project is still underway and new data is being acquired and monitoring will continue on the islands for a few more years at the least. Recovery is the ultimate goal of the Endangered Species Act.  It is hoped that once the native Spartina returns and the walls of the ecosystem are rebuilt, the California clapper rail will have a stable home once more and continue on the road to recovery.  For more information on this and other endangered species, visit www.fws.gov/sacramento.

Story by Ashley Cotter, Summer Intern, U.S. Fish and Wildlife Service, Sacramento Office
August 2, 2012