Double-crested cormorants perch on a resting and nesting platform at Will County’s Lake Renwick Preserve on Renwick Road, east of U.S. Route 30, in Plainfield, where they can be viewed along with great blue herons, great egrets, black crowned night herons and many other species of birds. Free guided viewings for all ages will be conducted from 8 a.m. to noon Saturdays June 21 and 28 and Aug. 4 and 11. Registration is not required.

Double-crested cormorants are named for two small tufts (or crests) of feathers on either side of the adult cormorant’s head, usually seen most vividly during mating season.

These goose-sized, turquoise-eyed beauties are something to behold. The Cornell Lab of Ornithology calls these gangly, snaky necked birds a “prehistoric looking” mix between a goose and loon, having matte black feathers and yellow-orange facial skin.

While they may been seen roosting in tree tops, these aquatic avians are water-loving creatures and expert divers. The cormorants’ webbed feet and sleek bodies make them natural swimmers and skilled opportunists when it comes to fishing.

Unlike ducks, cormorants’ feathers are not very waterproof. While having water resistant feathers protects a bird’s body from getting soaked, this oily coating isn’t great for diving. Cormorants’ feathers instead get waterlogged, allowing the bird to sink and dive more efficiently. Their solid bodies and dense bones also contribute to their excellent diving skills.

Their waterlogged feathers often make it look as if they are struggling in water. They often have just their faces and necks above the water’s surface and, after a dip, perch in trees or sit on rocks with their wings open to dry their feathers in the sun.

Double-crested cormorants can dive to depths of 25 feet, but some other cormorant species can reportedly dive to an astounding depth of 150 feet, which makes them some of the deepest diving birds.

When exiting the water, they tip-toe, moving both legs together in a hopping fashion, launching themselves forward and pumping their wings to gain momentum.

Having good wings for swimming, however, comes at a price when flying. Because they have short wings which are perfect to use as rudders, cormorants have the highest energy cost of any flying bird.

A cormorant’s diet includes a variety of fish and some crustaceans and, while its diving talents play a major role in assuring a steady stream of snacks, there’s more to their technique. Not only can the cormorant use its webbed feet to forcefully propel itself, but the tip of its bill forms a hook which is helpful for snagging lunch.

How is a cormorant like an owl? After eating, it regurgitates pellets containing fish bones and animal parts that can’t be digested.

If all of this isn’t enough to set the cormorant apart from many of its feathery counterparts, certain cormorant species in Asia reportedly have been trained to catch fish for people. For every seven fish caught, the cormorant gets to eat one.

In the United States, the double-crested cormorant population was in severe decline in the mid-1900s due to the use of pesticides. When these damaging pesticides were banned in the 1970s, fish-eating birds like the double-crested cormorant made a comeback.