It is not uncommon for a few shorebirds to linger over the summer
(especially larger ones like BBPL). Most shorebirds should reach sexual
maturity within 1 year, but some individuals won't. I used to work on
Cape Cod, and we had several individuals of Black-bellied Plover,
Greater Yellowlegs, Hudsonian Godwits, and a handful of Dowitchers and
peeps which could always be seen, every day of the summer. I.e. not
breeding. The BBPLs that stayed were inevitably still in basic plumage,
or only partly in alternate plumage.

I think you are correct in your assessment of the nomenclature for a
group of Knots; see if you can get 'tangle' accepted by the ABA?

Mike Smith
University of Washington
whimbrel at u.washington.edu