Wildlife of the Week!

© Five Star Whale Watching/ Jasspreet Sahib.

Today we fly to the rocky shores to spot a familiar bird species; the double-crested cormorant! This bird may appear similar to some other species on this coast, such as the Brandt’s or pelagic cormorant. Cormorants are an interesting seabird, in that they don’t have the same water-proofing abilities as some other water birds do. To find out more about this cormorant, read on below!

The double-crested cormorant is a robust, heavy, goose-sized bird and a skilled diver. Its body is usually dark, brown to black as an adult, with noticeable bright yellow/ orange skin at the base of the bill or on the bill. The bill color is an excellent way to decipher this species from other similar cormorants. Note that during breeding season, adult double-crested cormorants develop white or black tufts around their heads. Juveniles may also have a lighter appearance on their breast than fully grown adults.

The bird has a long, loon-like body shape (it is not highly related to loons, however) as well as a thin, pointed bill. The uppermost portion of the bill appears to taper downwards, and the entire bill is large, at a length about equal to that of the head. The bird holds an impressive maximum wingspan of about 50 inches. 

The double-crested cormorant is a widespread species throughout North America, its range reaching even as far south as the Bahamas. Interestingly enough, it is actually the most common type of cormorant in the continent. They are found both along the West and East coasts of North America, as well as at inland and freshwater sites. Northern individuals in Alaska are larger than most in North America, and those in the Bahamas are smaller than the latter above. Their habitats include freshwater sources like lakes, ponds, rivers/creeks, mangroves and coastlines. They are more often spotted in freshwater sites over the other two above-mentioned cormorant species. 

Cormorants, as diving birds, are successful predators in their habitats. They consume prey such as fish, aquatic invertebrates, amphibians and even plant matter. Their body sits low in the water and their swimming motion appears “duck-like” (though they are also not highly related to ducks). They may feed in groups, swimming under the water using their powerful webbed feet or even wings. They often stay in the upper to mid depth ranges to feed rather than seeking out the bottom.

Unfortunately, to sacrifice their excellent diving ability, cormorants have had to sacrifice oil to waterproof feathers. Without this oil, they are great divers but can become soaked after foraging. This is why it is necessary for cormorants to “dry-out” with their wings outstretched on land. 

The parenting of cormorants is cooperative, with both the male and female birds working to raise the young. Breeding occurs at about 3 years of age, and is initiated by courtship displays by the male, one part of a display includes him bringing forward bits of underwater weeds to the female. Nests are enacted by the work of both partners (building by female, gathering by male). They have a versatility for nesting sites which can include the ground, in trees, on cliffs or islands; these are often created in colonies with others of the species or other waterbirds. Complete independence of the young is expected around 9-10 weeks old. 

Double-crested cormorants have faced fluctuating population trends. A significant drop was measured in the 1960’s, being linked to the presence of DDT (insecticide)  in the environment, which caused significant harm to many bird species. Since the ban of these chemicals, the double-crested population has increased in number, with a continually expanding range. In some areas, however, they are purposefully eliminated by wildlife authorities due to the belief that they will impose on the success of other native bird species. 

So, next time you spot a bird with the features above, it is possible you are looking at a double-crested cormorant! You may see this cormorant dining, resting or drying with other cormorant species or other waterfowl. Read below to try some trivia about this species!

  1. True or False? A cormorant may regurgitate indigestible animal parts, just like an owl. (ANS: True).
  2. Cormorants spend a _____ (low, high, average) amount of energy flying. (ANS: High, the highest of all the birds).
  3. What is the double-crested cormorant’s maximum length measurement? (ANS: 27 inches).

BONUS CHALLENGE: 

Young double-crested cormorants are usually equipped to fly at what age range?

5-6 weeks.

Article Authored By: Alexa D., B.Sc./ Five Star Whale Watching. 


To learn more about this bird, visit our References below!

Audubon Guide to North American Birds.

The Cornell Lab.

eBird.

Forest Preserve District of Will County.

USGS.