Interesting. If I’m not mistaken, these birds are American avocet ( Recurvirostra americana). According to this page:
a black-and-white body and a rusty head and neck. During the winter the head and neck turn a grayish white
However, the illustration they show definitely has dark brown feathers.
This page:
https://ebird.org/species/ameavo
Look for bold black-and-white wings and long blue-gray legs
On some of the photos they have, the dark feathers on the wings really are black; on others, grey; on some others, definitely brown.