Some years ago, in a sad case of misplaced enthusiasm, I paid good money for a second hand book called Salt Glands in Birds and Reptiles. Well, £1.25 to be exact. (A friend reliably informed me that I had been ripped off.) While not the most thumbed volume on my shelves, there are treasurers to be found within. For example, the answer to important questions of the moment such as - why do eiders often have drips on the end of their noses?
I had already stumbled on the answer to this one when watching a friend who is an accomplished amateur taxidermist skin out a dead eider we found on the beach (freshly dead I hasten to add!). A distinctive feature of the eider is the high crown that gives the bird its unique profile (below).
I was intrigued to see that, once the skin was off, this profile was created not by the shape of the skull bones but by two large pinkish fleshy bits that lay on top of the skull, meeting in the mid line and overlapping the eyeballs. Salt glands. Take these away and the skull profile is very different - much flatter as you can see in the picture of the skull below. Compare the shapes and you get an impression of how big the salt glands are.
A closer look at the top of the skull shows where they lie - in the depressions in the bones and overlapping the eye sockets.
These salt glands enable the birds to excrete excess salt in the form of concentrated sodium chloride solution which runs down ducts and drips off the end of the
bill. Hence the snotty nose syndrome.
The size of these glands vary according to the amount of salt the bird takes in but most coastal birds have them - waders, ducks, gulls, etc. They help explain why ocean wanderers like fulmars can spend months at sea far from fresh water.