I showed two pictures to AI and found out:

Based on the size, shape, and markings of the bird in the picture, it is most likely a Spotted Sandpiper.

Here are some of the key features that helped me identify the bird as a Spotted Sandpiper:

• Size and shape: The bird is relatively small, with a slender body and long legs.
• Bill: The bill is straight and pointed, with a dark tip.
• Head and neck: The head is round, with a dark stripe down the center. The neck is white, with dark spots on the sides.
• Breast and belly: The breast is white, with dark spots. The belly is white.
• Back and wings: The back and wings are brown, with darker streaks.
• Tail: The tail is short and dark.

The bird in the second picture also exhibits the characteristic “teetering” behavior that is often seen in Spotted Sandpipers.

As you can see the bird was at quite a distance — and I was using most if not all of my 125x optical zoom to take these pictures.

I think it is just as likely to be a mis-identified juvenile herring gull, but with the distance it’s hard to know.