The Birds of the Ciénega de Santa Clara, a wetland of international importance within the Colorado River Delta

Abstract

The Ciénega de Santa Clara is the largest marsh in the Sonoran Desert and the most important wetland in the Colorado River delta. We present the information on the state of the birds in the Ciénega and a checklist of the species that have been detected at the site. We also summarize the ornithological work that has been conducted and compiled recommendations for bird conservation. A total of 261 species of birds have been detected in the Ciénega de Santa Clara, representing 71% of the species known to the Colorado River delta. The birds of the Ciénega include 189 migratory species (70.4%), 49 year-round residents (18.7%), and 28 breeding visitors (10.7%). Twenty-seven species are federally protected in Mexico, four of them as Endangered, eight as Threatened, and 15 under Special Protection. The Ciénega provides critical habitat for migratory waterbirds, with maximum counts of 280,000 shorebirds in the southern mudflats, as well as for breeding marsh birds, including Yuma Clapper Rails, Virginia Rails and California Black Rails, with maximum estimates of 8600, 7150 and 400 individuals respectively. Other species of concern that occur regularly in the Ciénega include Least Bittern, Snowy Plover, Least Tern, and Large-billed Savannah Sparrow. This wetland also provides important stopover habitat for 81 species of Neotropical migratory landbirds during their northbound spring migration, particularly for Wilson's Warbler, Swainson's Thrush, Yellow Warbler, Pacific-slope Flycatcher, and Willow Flycatcher. Binational cooperation is essential to protect the Ciénega in the long-term, especially in terms of dedicating the necessary water for its maintenance. Active management actions are also becoming an important part of habitat conservation, including land protection mechanisms, sediment removal, and fire management.