Every year, over half of all the world’s western sandpipers stop for a rest on the tidal flats just south of Vancouver, Canada. There they can be seen hopping and pecking around in the mud and water before continuing their northern migration.
It turns out that what the birds are really after is biofilm, a dense, mucous-like layer that forms on the mud. According to Environment Canada researcher Robert Elner, part of an international team that made the discovery, biofilm is actually an energy-rich substance that can make up to 70 percent of the diet of small shorebirds.
Researchers say this ‘magic mud’ is created by bacteria and diatoms that settle out of seawater and secrete mucus that binds them to the mud so they won’t be washed away with the tide. The film is composed of mucopolysaccharides, which is an easy-to-digest, high-energy food. This nutrient-dense ooze apparently helps keep the birds in good shape for migration and reproduction.
The scientists say that discovering the biofilm’s importance is key to not only better understanding shorebird populations, but also creating a more complete picture of the complex and dynamic food webs existent in nature. They also say the connection between shorebirds and biofilm is a “critical” link that could lead to better understanding of the birds, many of which are declining in number globally.
Photo Credit: USFWS