Saline Lakes: Migratory Bird and Human Connections

Shorebirds on Mono Lake, California.

Saline lakes of the Intermountain West such as the Great Salt Lake in Utah, Mono Lake in California, and Lake Abert in Oregon, provide some of the most important and remarkable bird habitats in the Pacific Flyway. These are highly dynamic systems whose size and avian use shifts dramatically from year to year. However, they are under increasing pressure from climate change and competition for scarce water resources in the rapidly growing West.

Naturally occurring saline lakes are terminal systems, meaning they have no outlet and water flowing into them only leaves by evaporation. They primarily occur in arid regions and their size, volume, and salinity are constantly changing in relation to seasonal and annual conditions dictated by environmental patterns as well as human water use. Historically, many of these lakes have waxed and waned in their salinity from near freshwater to brackish to hypersaline. The high salinity of these lakes often results in relatively low biological diversity but massive biological productivity. Species such as brine shrimp and brine flies are uniquely adapted to thrive in these systems and many migratory shorebirds and waterbirds congregate in spectacular numbers during their epic migrations to feed on these abundant halophile–salt tolerant–invertebrates.

Remarkable Bird Use of Saline Lakes
The network of saline lakes in the western United States plays an instrumental role in sustaining birds in the Pacific Flyway. The most important shorebird sites in the entire Pacific Flyway and Intermountain West occur in association with saline lake ecosystems. In fact, one of the most important sites for shorebirds in North America, Great Salt Lake, has been identified as a site of Hemispheric Importance, supporting at least 500,000 shorebirds annually, as determined by the Western Hemisphere Shorebird Reserve Network (WHSRN). Additionally, several other saline lakes are included in the Intermountain West Joint Venture 18 Key Shorebird Sites based on shorebird abundance and WHSRN criteria. 

Some birds are uniquely adapted to use hypersaline resources. Over 50% of the global population of Wilson’s Phalaropes stage at three of the most prominent saline lakes in the Intermountain West: Great Salt Lake, Lake Abert, and Mono Lake. These phalaropes need to fuel up before the long flights to their wintering grounds on high-elevation lakes in the Andes, as well as in the Patagonian lowlands and Tierra del Fuego. Many of the key sites along the way are saline lakes. The Eared Grebe also uses saline lakes as major stepping-stones to wintering areas in the southwestern United States and Mexico. Indeed, over half of the continental population of Eared Grebes can be found at Great Salt Lake during the fall migration. While staging in the fall, both the grebe and phalarope double their weight by eating halophile invertebrates in preparation for the long migrations. 

Challenges and Threats in a Changing World
Persistent drought conditions in the West over the past decade have corresponded with some of the lowest lake elevations on record at Great Salt Lake and Lake Abert. At the same time, an increasing human population in the Intermountain West is resulting in increased demands for scarce water resources and land-use changes affecting hydrologic patterns. Because saline lakes are located at the bottom of the watershed, growing competition for water creates an uncertain future for reliable inflows to sustain the functional integrity of the system. As freshwater inflows decline, lake volume decreases and salinity increases. When salinity increases to the point that even halophile invertebrates cannot tolerate, this important food resource is lost to migratory birds.

The environmental, social and economic values of saline lakes are generally not well understood or appreciated by society. These places are often perceived as wastelands because their water cannot be used directly for urban and agricultural purposes. However, with the growing concern for saline lakes, efforts are being made to better understand their ecological and economic values. For example, a recent assessment estimates that the Great Salt Lake alone provides an economic value of $1.32 billion per year from extractive industries (e.g. brine shrimp and minerals) and recreation.

The Future of Saline Water Conservation
Global trends for saline lakes portend these systems will be further stressed in the future. However, science, planning, communication, and stakeholder partnerships are growing to inform complex and contentious water use management decisions. Across the West, many agencies such as U.S. Geological Survey and Joint Venture partnerships are working to understand the network dynamics of and interconnections among saline lake, wetlands, and other aquatic resources at broad ecoregional scales. In addition, groups such as Audubon, other non-governmental organizations, industries, agencies, and municipalities have strived to find solutions to complex water and environmental issues that work for people and birds.

Addressing those problems is especially challenging due to the site-specific nuances of each system, diversity of stakeholder interests, and scarcity of water. However, setting conservation goals toward long-term functional integrity of these systems may lead to solutions amenable across diverse stakeholders and partnerships. Short-term, seasonal or periodic “declines” of salt lakes may sometimes make them temporarily unsuitable to migratory birds, but sustaining a functional network of dynamic saline lakes over the long-term will ensure the spectacular migrations of shorebirds and waterbirds persist.

Clouds of brine flies, like the one pictured above, provide a much needed food source for migrating birds.

2016 Summer Newsletter Articles:

Saline Lakes: Migratory Bird and Human Connections

Creativity Sparks Unique Watchable Wildlife Experience in Arizona 

Passion and Can-Do Attitude: The Spirit Behind State Conservation Partnerships

Tribal Bird Habitat Blossoms in Wyoming Wind River Basin Focus Area

Nominate a Conservation Champion, 2016 IWJV Awards Call 

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