For the second year in a row, Great Salt Lake reached new historic low levels. The lake receives its water from several rivers and precipitation, but as long-term drought, increasing water usage, and the reality of climate change set in, less water is coming to Great Salt Lake. This results in higher concentration of salts. While organisms of Great Salt Lake’s South Arm Ecosystem (Gilbert Bay) have evolved to tolerate higher levels of salinity than most, they do have limits. For instance, brine fly larvae and brine shrimp, and their main sources of food—microbial mats and their algae and bacteria are approaching – and even reaching – salinity thresholds.
While Utah actively works on solutions to get more water to Great Salt Lake and stabilize salinity levels, the conservation community, state agencies and stakeholders are starting to think about the potential implications to the migratory birds that rely on this ecosystem and its food resources. Numerous bird species will opportunistically feed on various life stages of brine flies and brine shrimp, but what bird species heavily rely on these briny macroinvertebrates? What is their level of reliance? What percentage of their populations are present at Great Salt Lake, and when?
National Audubon Society’s Saline Lakes Program, in partnership with the Utah Division of Wildlife Resources’ Great Salt Lake Ecosystem Program, worked with regional bird experts to answer these questions. The partners identified seven bird species, and using both published and unpublished scientific literature, created summary tables focused on their populations, timing, food resources, and habitat preferences during their time at Great Salt Lake. The species include:
- Wilson’s Phalarope
- Red-necked Phalarope
- Eared Grebe
- Northern Shoveler
- Green-winged Teal
- Common Goldeneye
- California Gull
Additionally, for three of these species that rely the most on brine flies and brine shrimp—Eared Grebes, Wilson’s Phalaropes, and Red-necked Phalaropes—we created more in-depth species profiles to highlight each.
It is important to understand the critical importance of Great Salt Lake to Eared Grebes and Wilson’s Phalaropes. Historically, Great Salt Lake hosted 50-95% of the North American population of Eared Grebes. While they visit Great Salt Lake each fall by the millions, adult birds will spend 3 to 5 months molting their feathers and building energy reserves feeding mainly on brine shrimp. During this time, their flight muscles atrophy leaving them flightless. This loss of the capability to fly makes Eared Grebes especially vulnerable to changing environmental conditions, particularly if there are changes in brine shrimp densities or their nutritional value cannot provide proper sustenance to the grebes. Some 33-40% of the global population of Wilson’s Phalaropes come to Great Salt Lake each year, peaking in July in August, mainly to feed on various life stages of brine flies. While they are not quite as vulnerable as Eared Grebes, both these species are highly dependent on healthy populations of brine flies and brine shrimp. What happens if the brine flies and shrimp are not here when the grebes and phalaropes arrive?
Audubon and its partners are actively engaged in exploring opportunities, data gaps and research needs to ensure the future health of Great Salt Lake’s ecosystem and the birds that rely on it.
If you would like to learn more about these species, you can check out the links to these documents below.