CORONA, Calif. (February 19, 2026) – The Orange County Water District (OCWD, the District) announced the results of its 2025 least Bell’s vireo monitoring program in the Prado Basin, documenting another strong year for the endangered songbird and reinforcing the long-term success of one of California’s most significant wildlife recovery efforts.

“The continued growth of the least Bell’s vireo population reflects decades of careful management at Prado Basin,” said OCWD Board President Denis R. Bilodeau. “Our work shows that we can protect and enhance critical habitat while fulfilling our mission to provide a reliable, high-quality water supply for north and central Orange County.”

OCWD’s vireo program has been one of California’s great environmental success stories. When it began in 1986, there were only 19 vireo territories in the Prado Basin. Through habitat restoration and parasitism management, OCWD brought the species back from the brink of extinction and successfully helped the vireo to flourish. During the 2025 breeding season, biologists recorded 684 territorial males, 272 breeding pairs, 121 nests, and 441 fledglings. In addition, reproductive success was seven percent higher than the previous year.

District staff conducted near-daily monitoring from March 17 through September 15. Findings are documented in the report Least Bell’s Vireos and Southwestern Willow Flycatchers in Prado Basin of the Santa Ana River Watershed, CA, fulfilling coordination and reporting requirements with the U.S. Fish and Wildlife Service and U.S. Army Corps of Engineers.

2025 marked the 40th consecutive year of vireo monitoring by OCWD. The report’s author, consultant Jim Pike, contributed to 37 of those monitoring years prior to retirement. Monitoring and habitat management will continue under OCWD’s established program framework.

The District owns and manages 2,150 acres of wetlands within the Prado Basin as part of its water supply operations. Long-term improvements have strengthened riparian conditions, increased vireo nesting activity, and improved Santa Ana River water quality while supporting groundwater recharge. These efforts help maintain the Orange County Groundwater Basin, which supplies approximately 85% of the drinking water for 2.5 million residents. The District will continue to manage the Prado wetlands to support reliable water supplies and effective habitat stewardship. For more information, visit www.ocwd.com.