Pewter clouds hung heavy over the inlet, a cold reflection of the sudden onset of winter weather. On the dark waters, scores of waterfowl were jostling for food and space. There were lots of ducks, gadwalls mostly, but my attention was fixed on a pair of black-and-white diving birds.

One disappeared under the opaque waters, and the other followed suit moments later. I counted off the seconds while I scanned for their return. Ten. Eleven. Twelve. Then the first reappeared a dozen yards from where it had submerged. The second bird waited another four to five seconds before surfacing.

Horned grebes (Podiceps auritus) are regular winter residents of the Chesapeake Bay, and Calfpasture Cove seemed to be a favorite location. I often find them here on regular winter visits to the Eastern Neck National Wildlife Refuge near Rock Hall, MD.

Most birds go through multiple plumages each year, with the flashiest variation on display during breeding season. In winter, most species have more subdued colors and patterns during what’s called their “basic” plumage phase. Horned grebes are no exception.

As the birds surfaced from another dive, I got a good look at their two-toned heads. The top half of the horned grebe’s head is black above its eyes, with a thin black stripe that continues down the nape before broadening into its dark back and wings. Below the eyes, which are red, a white cheek patch blends with the pale neck and undersides.

They look like someone dipped them in paint, all brownish black on the top and uniformly white below.

These grebes aren’t very big — about a foot long with a wingspan of double that length. They were riding low in the water, like other diving waterfowl, which made them seem even smaller next to the big, bulky gadwalls.

Horned grebes have small, pointed black bills with pale tips. The sexes look alike.

Horned grebes fly with their necks fully extended.

Here at the refuge, the grebes were diving for food. They eat fish and lots of other small aquatic animals. In warm weather, they eat insects, but there were no bugs on this chilly morning.

Curiously, horned grebes eat a substantial number of their own feathers, usually plucked from their bellies or flanks. The purpose of this behavior, counterintuitively, is to aid digestion.

The feather wad holds fish scales and bone while the stomach digests the rest of the prey. Some of these hard-to-process parts are slowly dissolved by the bird’s stomach acids, but many are not. They are later expelled as pellets, a function that also helps the bird rid itself of parasites.

Horned grebes even feed their chicks feathers, so the process starts early in life.

The horned grebes here at the refuge had come from western Canada or Alaska. The birds breed on freshwater ponds and marshes across the Arctic. Different subpopulations of the species are found from Norway to Siberia.

Pairs are monogamous and share the responsibility of building the nest and tending to the young. The floating nest is constructed of aquatic vegetation. The chicks can swim after a day but will stay with their parents for weeks, often hitching rides on the back of mom or dad, even underwater.

Horned grebes have a showy breeding plumage. The black head has yellowish feathers behind the eyes that can be raised or lowered at will.  These are the eponymous “horns.” Breeding plumage also includes chestnut neck and side feathers with a speckled black-and-white back and wing coverts.

After the young have hatched, the adults lose all of their flight feathers at once, stranding the birds on the water until the basic molt feathers grow in. Flightless grebes can avoid predators through their excellent swimming skills, aided by their lobed (not webbed) toes.

The handsome breeding plumage is accompanied by extraordinary behavior. The birds have complex courtship rituals. Ornithologists describe four pair-bonding ceremonies — discovery, weed, head-shaking and triumph — as well as separate, well-defined displays related to nest selection and copulation.

These displays include ones in which the pair rises up into a “penguins dance” as it races upright across the water side-by-side, with head plumes flared.

The pair on Calfpasture Cove showed none of these stunning behaviors. These birds were busy with the quotidian activities of escaping the deadly arctic weather and finding their daily meals.

As the birds dived out of sight again, I thought about how so much about this species is hidden from my view. The dark, cold waters of the Chesapeake masked their swimming skills. The season and my location blocked views of their breeding plumage and the elaborate rituals of their mated lives.

The winter guests made one thing clear: a seemingly colorless existence is not always what it seems.