CHARADRIIFORMES: Scolopacidae
Calidris himantopus
The association of the Stilt Sandpiper with Curlew Sandpipers was not a peaceful one for the Stilt Sandpiper.
It was often "chased" a little distance by Curlew Sandpipers when it fed too close to them.
The bird in the air is the Stilt Sandpiper reacting to a rear end attack.