During a visit to Willard Beach in South Portland recently, I was delighted to see several common eider ducks and double-crested cormorants as they dove for food among the small boats tethered in the cove. A special treat, however, was the sight of a black-crowned night heron flying overhead.

Herons are an interesting and diverse family of birds. Although the great blue heron is probably best known and most often seen, the smaller herons have a certain mystique about them- especially this little night heron.

As its name suggests, this bird is nocturnal, concentrating most of its feeding and other activities during darkness or in the dim hours just before dawn and after sunset. This enables the bird to avoid competition with other members of its family that share its habitat and are active during the day.

During the breeding season this heron is more likely to take a chance against its daytime competitors, due to the increased feeding demand with raising a family. It has often been photographed poised just above the surface of a pond. Streamlined and elegant, it is one of nature’s perfect sculptures as it stands momentarily frozen, ready to aim its beak with deadly precision at its intended target.

For the most part, though, this heron is a creature of the night, and is often seen at dusk as it flies to its nighttime feeding area. The “Birds of North America” species account describes it succinctly: “For naturalists who enjoy the shore and marsh, this heron’s distinctive call is a quintessential sound of dusk and night.”

This heron’s call is nothing if not distinctive, but it’s not a sound you’d associate with a secretive creature of the night, let alone a bird. It is not at all like the eerie wails of the loon, or the haunting notes of an owl; nor does it in the least bit resemble the sweet whistled notes of a whipporwill.

Instead, it sounds like a barking dog. A barking pug dog, to be more exact.

The first time I head this sound, I was convinced someone had either lost or abandoned their dogs in a nearby marsh. When I went to investigate, the birds took flight, calling as they went. Mystery solved.

Other than its nocturnal habits and odd-sounding call, the black-crowned night heron is pretty ordinary. It doesn’t require any one type of habitat, nor does it have a specialized diet. It is, according to the BNA, a “cosmopolitan species, breeding on every continent except Australia and Antarctica.” It occupies many different freshwater and marine habitats, and feeds upon a variety of items, although fish figure largely in its diet.

Black-crowned night herons are thought to be monogamous; however, instead of nesting singly, they nest in colonies with other night herons and with day (diurnal) herons. They raise only one brood in each breeding season.

These little herons may not be as flashy or impressive as their larger relative, the great blue heron, but they do have a lovely elegance about them. Their style of flight is also very distinctive; their wingbeats are heavy but quick, and their wings don’t seem to straighten out after a downstroke but retain a slight bow to them.

So if you see a slightly larger than gull-sized bird flying with bowed wings at dusk, chances are it’s a black-crowned night heron.

And if it sounds like a little pug dog barking, that’s a dead giveaway.

BDN bird columnist Chris Corio can be reached at bdnsports@bangordailynews.net