New research has taught us something fairly unbelievable about what Western Sandpipers Calidris mauri eat to help them on their northward migration along the western coast of North America.
Dr Robert Elner has spent some time watching Western Sandpipers on the Fraser River estuary, more than twenty years to be more precise, and he observed that although some waders followed the ebbing tide all the way out to feed, some of the smaller ones did not. They remained in an area further up the mud flat and went no further. This puzzled him, as well it might.
What he observed was that the area where the Western Sandpipers were feeding was covered with a green slime and he wondered if this had something to do with their choice of feeding spot.
Determined to find out he observed the birds closely and found that they seemed to be slurping up the goo. Investigating further he discovered that the stomach content of the Western Sandpipers almost entirely consisted of the green slush and there were, contrary to expectations, few crustaceans, molluscs and other invertebrate food stuff.
He asked Prof. Peter Beninger to study the mouth-parts of the Western Sandpiper very closely and he discovered that they have feathery tongues and that within these feathery filaments were lodged many particles of the goo.
|This is a Western Sandpiper on the east coast of North America; is it lapping goo too?|
So what is this goo? Well it is technically called Biofilm.
Biofilm is made up of things called Diatoms which create their own food from sunlight; carbohydrates and omega 3 fatty acids. They also secrete a sticky substance which binds them together and to the mud so they can withstand the ebb and flow of the tide water. The Western Sandpipers use their feathery tongues to slurp this stuff up and it provides them with sufficient energy to fly on north for another 1000km to their breeding grounds in the Arctic.
Full story and more information here: https://www.hakaimagazine.com/article-long/slime-shorebirds-and-scientific-mystery