Cooperative Fish and Wildlife Research Units Program: Idaho
Education, Research and Technical Assistance for Managing Our Natural Resources

Since 2005, the number of Yuma Ridgway’s Rail (Rallus obsoletus yumanensis, hereafter ‘Rail’ or R. obsoletus) detected through standardized surveys across its range has decreased by 52%, declining to 432 individuals in 2013 (USFWS 2014). Most of this decline has occurred at managed wetlands near the Salton Sea, California. The reasons for this decline are not known.

Incidental fatalities of the rail have been reported at renewable energy facilities within the species range. The current fatality monitoring at renewable energy facilities was not designed to be able to evaluate total species impacts, or rare events of injury or fatality of an endangered species. Currently the species is restricted to small patches of emergent wetland vegetation impacted by multi-year drought, disconnected by large expanses of agricultural lands and open desert with solar facilities possibly attracting dispersing individuals that mistake the reflection from the solar arrays as water. The species is known to make long range dispersal movements from areas where prolonged drought and water use are currently having a deleterious impact to this water-dependent bird.

OBJECTIVE:
Determine the dispersal distances, dispersal direction, and dispersal behavior of juvenile Yuma Ridgway’s Rail.

METHODS:
We will attach PTT transmitters to 10 hatch year (HY) rails to determine dispersal distances, and the conditions under which young birds move to find new habitat patches.