Is the bird in the photo a dunlin? No, the bill is too short, but you're looking at the same family.
Is it a sandpiper? No.
Again the bill is too short and it doesn't curve. Yes, it sure does look like a semipalmated sandpiper with its short bill, spotted neck and large spots on its wings. It's hard to tell from this photo, but our bird in discussion is larger (about 8 inches) like the dunlin. However, the wing coverts are lighter in color than those of the sandpipers. This isn't the easiest bird to identify, is it? Wait. Is our bird sick? Its feathers look odd. No, it's not sick, but it is molting. Maybe that's like a teenager losing his or her baby fat. The difference is that the bird molts every year. A better analogy would be of humans buying new clothes to look better.
When you are walking a beach by the ocean, look for the sanderling chasing the water moving up the beach and then receding back. They are hunting for mollusks and small crustaceans. You might see the holes left after their feeding. Even though they favor the beaches by the oceans all over the world, they sometimes visit inland lake beaches and mud flats.
Can you think of a bird that will pretend to have a broken wing to distract you away from its nest of young? The sanderling has a distraction display, too.
Breeding occurs in northern Canada. Usually, the males are quite scattered, but then, they might also group near each other. The size of their territories depends on the prey. They are definitely discouraged in having a big area, if more enemies are found where they stayed the previous winter.
Let's discuss their family life. Mostly they are monogamous (mating one female at a time), but that's not a steadfast rule. Sometimes they practice sequential polyandry, which is practiced mostly by shorebirds. However, less than 1 percent of all birds do this. Polyandry means that one female will mate with at least two males, maybe even more. The female is often larger and with more colors than the male. Also, the male raises the young while the female tries to attract more mates. The sanderling practices sequential polyandry. The female lays a clutch of eggs, the male incubates them, and the female lays another clutch which she incubates. This practice provides the female a better chance of producing young with better survival rates.
The next time you're traveling to the tundra, look for the nests in dry sedges. The nests are lined with grass, leaves, and lichen. It's the female's job to find a location for her scrape. What's a scrape? It is such a shallow dip in the sand, that they have to build a rim around it to keep the eggs from rolling out.
Back to the sanderling. With bill open, it can probe up to 10 mm deep for its food. I looked up the conversion: 1 millimeter equals 0.03937007874 inches. Let's round that up to .04 inches. Thus, 10 millimeters equals .4 inches. As it moves up the shore, it might join other birds. In the spring, its diet changes to spiders and veggies.
This bird is in the Calidris family with sandpipers and dunlins. This was a rare sighting for our area. Somebody spotted one up north, on the shores of Lake Ontario. In the winter, this bird heads south for the West Indies and coasts of South America. Sounds good to me.