Blanca Wetlands: The Importance of Science-based Management When Resources Run Dry

These salty waters are prime habitat for the invertebrates that shorebirds crave.

Gem-like wetlands nestle in the high-elevation desert of the San Luis Valley in south-central Colorado. These saline waters teem with millions of invertebrates that more than 47,000 shorebirds depend on during their migration. One portion of these wetlands is known as the Blanca Wildlife Habitat Area (Blanca WHA), which is an essential stopover site for shorebirds.

As a crucial place for birds, the Intermountain West Joint Venture’s (IWJV) Shorebird Science Team wanted to know how many birds the Blanca WHA could feed.

Blanca WHA is comprised of about 10,000 core management wetland acres, many of which are mudflats and saline playas. The wetland complex is intensively managed by the Bureau of Land Management (BLM). Significant numbers of Baird’s sandpipers, Wilson’s phalaropes, western snowy plovers, and American avocets flock to these basins for a buffet of brine shrimp and flies. Blanca WHA is in the middle of the flyway between South America, the Gulf of Mexico, and arctic, boreal, and prairie breeding grounds, making it of international importance to these birds.

“The habitat found on the Blanca WHA used to be more widespread in the San Luis Valley, but today it is one of the few remnants,” said Sue Swift-Miller, Manager of Blanca WHA. Current drought conditions, as well as competition for limited water resources, have vastly reduced the availability of playa wetland habitat and make the habitat at Blanca WHA all the more important. 

Migrating shorebirds stop over at Blanca to build fat reserves before continuing their travels north or south. As such, Blanca WHA managers control the area’s water to produce as much fairy shrimp, brine shrimp, brine flies, and other invertebrates as possible. 

American avocets feed on the invertebrates found in Blanca WHA's saline waters.

Using a bioenergetic approach, the IWJV Shorebird Science Team studied how much food energy the area actually provides versus how much food energy the birds need from this site during their migration stopover.

“The team used the best available information to conduct a habitat assessment that compared the amount of invertebrate energy available in playa wetlands to the energetic needs of all migrating shorebirds,” said Brad Andres, Shorebird Science Team Member and National Coordinator for the U.S. Shorebird Conservation Plan.

To step down the U.S. Shorebird Conservation Plan’s continental shorebird population objectives to fit Blanca WHA the Shorebird Science Team use three major criteria: the Plan’s shorebird population estimates for the IWJV region, their knowledge of regional limiting factors, and the region’s ability to contribute to each species’ population levels. This information helped establish objectives for Blanca WHA.

One of the most important findings from the IWJV Shorebird Science Team study was current food availability might be limiting the ability of shorebirds to accumulate adequate fat reserves during the peak of migration in August. With this knowledge, Blanca WHA managers made management changes to allocate more water during that time to ensure there is enough for invertebrates and the birds during this important migratory period.

A feast of invertebrates fills the air and birds dart about open-mouthed to catch their fill.

“With this science behind our management, it gives us the confidence that we are using our limited water resource for the maximum benefit,” Swift-Miller said.

The extensive survey data that the Blanca managers had to support the bioenergetics study resulted in strong science that can be applied to management practices.

“Working with the IWJV on the application of the bioenergetics model has allowed BLM to use science to direct our management to meet important species needs,” said Jill Lucero, also a Blanca WHA Manager. “We greatly appreciate the efforts of the IWJV to partner with us to identify our critical management needs for our site.”

The IWJV has released its 2013 Implementation Plan! Check out the plan’s Shorebird Chapter to read more about how the JV is stepping continental shorebird objectives from the U.S. Shorebird Conservation Plan down to the Intermountain West. Also, to learn more about the importance of the Intermountain West to shorebirds, check out this article.


Read more articles in the Fall 2013 issue of the Conservation Roundup: 

The Shorebird Character of the Intermountain West

By Brad A. Andres, National Coordinator, U.S. Shorebird Conservation Plan, U.S. Fish and Wildlife Service

Partners Persevere for Rio Grande Despite Colossal Drought

By Alan Hamilton

Pond It and Plug It: Restoring Wet Meadows in Northern California

By Jim Stutzman, IWJV Habitat Delivery Specialist

Farm Bill Conservation Programs Take Root in the Palouse

By Kurt Merg, Partners for Fish and Wildlife Program, and Don Larsen, Washington Department of Fish and Wildlife