The wind was very calm, so it was easy to hear the Sanderlings calling. I'm a little embarrassed to share that I learned something about Sanderlings tonight that I hadn't realized before, even though I've been watching and listening to them for over 20 years!
But while I was trying to photographs these birds, my camera landed on one bird that was making the series of notes. This bird was different than all of the rest in that it had its back feathers raised and it was chasing other birds that were nearby (see left-hand bird below).
It would alternate calling/chasing and feeding, but it kept its back feathers raised the whole time, so it was easy to pick out among all of the other birds.
Here's another view of the elevated feathers (left-hand bird again):
The series of notes was not just a "keep-in-touch" call by several individuals, but it was an aggressive territorial call by one particular Sanderling. My experience of watching and listening to the flock completely changed after realizing this. Next time I'll bring a recorder so I can share this sound with you.
There are a couple of other interesting things about this sound and behavior:
- Here's the voice description in Bent (1927): "The note of the Sanderling is a soft ket, ket, ket uttered singly or in series somewhat querulous in tone. It is at times used in taking wing, also with variations in the conversational twittering of a feeding flock." Although this is a brief statement, the word "querulous" may be important as it leads you to think the author had the impression that the birds were "unhappy" about something (e.g., in tonight's case, that another bird was intruding on its feeding territory).
- The Sounds section from the Birds of North America was also intriguing. "Relatively quiet outside of male Display Flights and adult distraction displays in the high Arctic, so sounds are largely unstudied. With only a few published sonograms and no tape-recorded contextual analysis of vocalizations..." It's somewhat surprising for such a common bird, but it appears as though no one has taken the time to fully document and describe these territorial calls made during the non-breeding season.
- The Sibley Guide to Birds has one line that says, "Threat a high, thin, relatively slow twee, twee, twee..." I don't know if this refers to the territorial calls?
Here's one more picture of the Sanderling that humbled me. And now I'll never forget what a territorial Sanderling sounds like!