The 50 feet between me and the river is a tangle of trees and underbrush. The naked branches of winter offer a clear view of the red oak as it leans precariously over the water. A single bird perches on a bare limb, gazing into the frigid black current below. Her blocky, crested head and heavy bill seem too big for the blue-gray body, short tail and stubby legs.

The sentry drops off her perch. A few wing beats take her a short distance upstream to where she hovers momentarily over the water. The dagger bill drops and the big head seems to pull the rest of her body like a stone into the shallows. Almost immediately, she scrambles out of the water, bill empty. She missed the fish that was her intended prey. In defeat, the bird returns to its solitary outpost.

Belted kingfishers (Ceryle alcyon) can be found near water all across the United States. Ponds, lakes, rivers and streams provide suitable habitat so long as a perch is nearby. These birds are short-distance migrants, heading as far north as Canada during the summer or down into Mexico in the winter. For most kingfishers, though, their entire range is within the lower 48 states. Many, like the one here fishing the Nanticoke River, are year-round residents.

There are three kingfishers in North America, but the belted kingfisher is the only one routinely seen north of the Rio Grande Valley. A bit bigger than a robin, it is blue-gray above with a wide, white collar. The belt is a broad chest band of the bird's dominant blue. Otherwise, the bird is white underneath. The big blocky head has a shaggy crest. Its fearsome bill is slate gray with a bit of white at its base. The bird's legs are surprisingly short.

In most avian species, the male is more colorful than the female, but not so with the belted kingfisher. The bird I am watching is female. She has a second belt below the first that is a rusty red. The color extends into an irregular rusty patch under the wings. Males lack this splash of rusty red.

In yet another avian oddity, belted kingfishers make their nest underground. Using their formidable bills and short feet, the parents jointly excavate a tunnel into a riverbank. At 2 inches, the burrow is just wide enough to allow the birds access. The cavity can extend 3-10 feet. At the end of the slightly inclined tunnel, the birds make a modestly enlarged chamber.

Eggs are laid and incubated without the benefit of any nesting materials. Both parents-which are monogamous and mate for life- sit on the eggs and share early feeding duties for the single brood they raise annually.

They teach the young how to feed by dropping freshly caught and killed fish into the water. The young birds have to dive in to get their meals. Within a short time, they are catching live fish. The parents continue to supplement the growing chicks' diet until the youngsters become proficient in fishing.

Belted kingfishers are not exclusively fish eaters. They will take frogs, salamanders and even eat some insects.

But the bird is aptly named. The prototypical picture of a belted kingfisher is one of a solitary bird, on a low perch, overlooking water, keeping a sharp eye out for its next meal.

Kingfishers give a harsh, rattling call when defending their territory. A low perch with a clear view of the waters below is a prize worth defending. Once these birds find a favorite spot, they return to it faithfully.

When a kingfisher spots a fish in the water, it drops from its perch ready to attack. It may hover briefly over its prey before plunging headfirst into the water, grabbing fish in its bill. The bird immediately returns to its perch where it kills and devours its food. During breeding season, it will take bits of fresh fish back to the nest to feed its young.

The female that I am watching seems unperturbed by the lack of success on her recent dive. It is the dead of winter; she has no young to feed and no tunnels to dig. She simply sits alone, watching the river slide by, looking intently below the river's surface for her next meal.

Like this riparian sentinel, for the moment I have faithfully discharged my obligations. Now is the time to be alone. As time slides by, I try to peer below the surface of my life, searching for the sustenance I need. Everything I need is here, although no perch will guarantee success with each dive. But still I return, rebalance and keep watch.