Movement Ecology and Survival of Light-footed Ridgway's Rail
April 2020 - December 2023
Light-footed Ridgway’s Rails (Rallus obsoletus levipes) are rare and are restricted to a small geographic range that spans the U.S.-Mexico border. They persist in a landscape with high density of humans, growing human populations, and increased habitat fragmentation and degradation. Despite their rarity, very little is known about their abundance, distribution, seasonal movements, and connectivity among occupied marshes. Better knowledge of these characteristics is critical to effective population recovery and management. USFWS and CDFW biologists are interested to obtaining: 1) a more rigorous and more replicable estimate of range-wide abundance, 2) a more rigorous estimate of population trend, 3) a range-wide approach for estimating probability of occupancy for all marshes, and 4) estimates of the frequency of movement within and among marshes, for wild and captive-reared birds. The recovery priorities in the LFRR Recovery Plan addressed by this proposal include: Examine rail population dynamics, Assess rail habitat requirements, Analyze rail habitat utilization patterns, and Determine numbers, distribution, population trends on annual basis in the U.S., all of which have a #1 priority ranking.
The goals of this project are to improve our knowledge of the distribution, abundance and movements of this endangered bird, to develop and disseminate standardized population monitoring methods for the species, and to assess the effectiveness of current recovery actions. Documenting where LFRR are present, how many are present, and how individuals move among the fragmented marsh habitats they occupy is critical to effective management of the species. These data are specifically mentioned as priority needs in the recovery plan for the LFRR.
Design and implement a statistically rigorous monitoring protocol via standardized call-broadcast surveys within marshes throughout the bird’s U.S. range.
Assess the effectiveness of current recovery actions by attaching solar-powered satellite GPS transmitters to wild-caught and captive-bred rails so that we can compare home range size, seasonal movements, habitat associations, connectivity among populations, dispersal, and survival.