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Tiny crustaceans and insects carry energy from Great Salt Lake's microscopic producers to its birds.
Brine shrimp and brine flies are different animals with different life cycles. A brine shrimp is a small aquatic crustacean, while a brine fly is an insect whose winged adult is the familiar shoreline form. Algae and other tiny organisms support this food web; shrimp and flies make that production available to feeding birds. The lake is not biologically empty because it is salty, and the two conspicuous invertebrate groups should not be mistaken for its entire diversity of life.
Shrimp populations renew through hard-walled cysts containing dormant embryos. In favorable conditions, females can also produce live young. Temperature, salinity and other conditions influence development and reproduction, so the rhythm is more complicated than a fixed date on the calendar. The cyst stage helps bridge difficult periods, including winter. It also supports a commercial harvest: DWR monitors the population and regulates collection with the aim of leaving enough cysts to sustain the lake's next generation.
Brine flies pass through egg, larval, pupal and adult stages. Much of their life happens in the water, where immature stages feed and develop; adults are short-lived. Larvae can overwinter below the surface. The living shoreline therefore includes more than the cloud of adults a visitor notices. Keeping feet and equipment off fragile lake-bottom structures and leaving feeding birds undisturbed helps protect the setting in which these small animals support a much more visible migration.
Swimming shrimp are crustaceans; shoreline flies are insects. Do not identify all small lake insects as one species.
Lake conditions affect the food web; commercial shrimp-cyst harvest is managed separately from wildlife watching.
Watch from established access areas. Do not collect animals, disturb lake-bottom structures or push feeding birds away from the shore.
A small diving bird whose long autumn stopovers reveal the importance of Great Salt Lake's invertebrate food supply.
An upturned bill, blue-gray legs and a sweeping feeding motion make this wetland shorebird especially distinctive.
A large white migrant whose family groups link Utah's wetlands with Arctic nesting country.
Read the refuge as a changing set of habitats, from shallow feeding flats to marsh cover and deeper water.