Ecology and Population Dynamics of Ridgway's Rails along the West Coast of the U.S.

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The Ridgway’s rail is a federal and state listed endangered species that occurs in wetlands along the Pacific Coast and from the Lower Colorado River drainage to southern Baja California. Three subspecies of Ridgway’s rail are found within the United States: the California Ridgway’s Rail, Yuma Ridgway’s rail, and Light-footed Ridgway’s rail.  All three subspecies have declined since 1900 as a result of habitat loss, with interference with tidal flow as the most common mode of habitat degradation. Critical information on this species’ movements, habitat use and survival are not well understood. Explore this project to learn more on how WERC's Mike Casazza is investigating the ecology and population dynamics of the Ridgway’s rail to inform conservation and management of this endangered species and its habitat.

WERC Ridgway's rail marked to track movement
Ridgway's rail marked to track movement.(Public domain.)

USGS scientists are investigating the ecology and population dynamics of the Ridgway’s rail throughout its range to inform conservation and management of this endangered species and its habitat in the context of urbanization and other trends in land use change. The knowledge that will be gained from the undertaking of this study will prove useful for land managers seeking to not only protect the Ridgway’s rail but also to conserve and improve existing wetlands along the Pacific Coast as a whole. As such, this study will support the USGS Ecosystems mission area, which is committed to providing unbiased science, tools, and decision support to the Nation’s natural resource managers.

Today the California Ridgway’s (former Clapper) rail continues to face a multitude of threats including continued habitat loss and degradation, predation by both native and non-native species, and sea-level rise. As a result, long-term population persistence of the endangered California Ridgway’s rail is likely to become increasingly reliant on management intervention. We will continue to monitor populations throughout Suisun Marsh and San Francisco Bay remotely through the use of acoustic recording devices.  We will also integrate additional acoustic detection software/techniques to streamline data processing and refinement of autonomous survey protocol.  We will coordinate with and inform the California Ridgway's Rail Recovery Team and provide science support for transition zone management projects led by Point Blue Conservation Science. In addition, we will analyze movement data for Yuma Ridgway's rail and assess mercury levels in Yuma Ridgway's rails and rail prey in the Salton Sea. We will conduct surveys for rails and assess seasonal population redistribution in Yuma rails. Finally, we will continue to work on manuscripts related to movement data, habitat use, and behavior.

Objectives:

  1. Study Ridgway’s rail demographics to determine current status of populations.
  2. Examine habitat use and movement patterns of Ridgway’s rails to determine habitat needs and preferences.
  3. Investigate impacts of environmental factors on Ridgway’s rail to inform decisions regarding wetland management (effect of invasive Spartina control, impacts of contaminants, and impacts of disease).
  4. Analyze genetic trends in the Ridgway’s rail across its range to examine effects of land use change on Ridgway’s rail populations.
WERC Ridgway’s rail in vegetation
Ridgway’s rail in marsh habitat. (Public domain.)