In response to Bert Guttman's question:

One-legged feeding by Dunlins is something we often see here, and is also
practiced by Western and Least sandpipers and I believe by other shorebirds.
I agree that it's a method of thermoregulation (heat retention), but it may
also be just restful feeding.

Another interesting behaviour noticed at Witty's Lagoon (near Victoria) on
Sunday was perhaps stimulated by a Merlin that was periodically rocketing in
on about 300 mixed shorebirds. The tide was rising, thus reducing the amount
of open mud and edge. In fact, the only remaining mud was close to the
Salicornia ond other salt-tolerant plants lining the edges. These plants
limit the peripheral vision of the shorebirds -- not a good thing when a
fast, low flying raptor is in the area. Thus, many of the birds crowded onto
a partly submerged log in the open water....perhaps 100 Short-billed
Dowitchers, Black-bellied Plovers, Dunlins, Western and Least sandpipers. As
more Dunlins arrived, there was no room at the "inn", so some of the arrivals
settled gently onto the backs of the dowitchers. The larger birds actually
tolerated the Dunlins for a few seconds before shaking them off or flying up,
only to lose their spot on the log, often to the more maneuverable Dunlin
interloper.

Behaviours are what make this hobby so fascinating...behaviours of birds and
of birders!

Bryan Gates, Victoria
bgates at assessment.env.gov.bc.ca