Science to Help Birds and Reduce Costs in the Colorado River Delta

For more than a decade, Raise the River—a binational coalition of NGOs that includes Audubon —has been restoring habitat in the Colorado River Delta. A new publication shows how additional efforts could optimize sites for restoration where it provides maximum benefits for birds, offering a vision for efficient restoration that could eliminate guesswork and reduce implementation costs. Not only will this have benefits for birds, habitats, and communities in the Colorado River Delta, but it could allow for each drop of water and each dollar in the Colorado River Delta to be utilized more strategically—a welcome advancement in an over-extended river with many interests and tradeoffs constantly at play.

Due to a century of water development upstream, the Colorado River does not flow in its final 100 miles, effectively eliminating the Delta’s vast, lush ecosystem of riparian forests and wetlands. Notably, birds like the Willow Flycatcher and Song Sparrow have experienced population declines, and six additional species have been locally extirpated. The degradation and loss of riparian forest is a key factor driving these declines.

Working in partnership with the U.S. and Mexican federal governments under the terms of successive treaty agreements (Minute 319 and Minute 323), Raise the River combines engineered water deliveries with reforestation in the Colorado River floodplain to reconnect the Colorado River ecosystem from the U.S.-Mexico border where its flow is eliminated, to its mouth at the Upper Gulf of California.

The new study published in the Journal of Environmental Mangement and led by the National Audubon Society in collaboration with Mexican partners at Pronatura Noroeste and U.S. partners at the United States Geological Survey, U.S. Bureau of Reclamation, University of Arizona, University of Colorado, and Cornell Lab of Ornithology, sought to strategically prioritize locations for riparian forest restoration based on their significance to priority birds. Additionally, given the high cost of active restoration, the study aimed to estimate the extent of landscape restoration needed to maximize the abundance and diversity of the bird community.

Rather than relying on non-ecological factors such as irrigation costs, the study employed a data-driven approach, utilizing machine learning and systematic conservation planning techniques. By predicting bird distributions across simulated landscapes with varying restoration scenarios, the research identified the most crucial locations for restoration. The authors combined bird and vegetation survey data collected by Pronatura Noroeste, with a high-resolution land cover map created by partners at the University of Arizona, to enable precise predictions, allowing for strategic allocation of resources to maximize the benefits of restoration efforts.

Stefanny Villagómez, expert avian Conservation Biologist with Pronatura Noroeste noted, “Audubon’s analytic expertise, combined with Pronatura Noroeste’s extensive monitoring data record, enabled us to develop an innovative approach to restoration that should improve outcomes for birds.”

This analysis represents the first data-driven, strategic restoration study for the Colorado River Delta. By aligning restoration efforts with predicted bird distributions, the ultimate goal of this research is to provide decision support that will help revive the once-vibrant bird community and restore balance to this threatened ecosystem. Future research could expand this analysis to other regions in need of restoration.

Minute 323, the current binational Colorado River Treaty agreement—which includes commitments for environmental restoration—expires in 2026. As U.S. and Mexican decision-makers negotiate a renewed agreement, this new publication provides a roadmap for targeting restoration to improve outcomes for focal bird species, optimizing restoration investments, and ultimately for allocating funding to monitoring and science that provides a strong return on investment.