Upload

Loading icon Loading...

This video is unavailable.

Double crested cormorant

Sign in to YouTube

Sign in with your Google Account (YouTube, Google+, Gmail, Orkut, Picasa, or Chrome) to like Alan Heath's video.

Sign in to YouTube

Sign in with your Google Account (YouTube, Google+, Gmail, Orkut, Picasa, or Chrome) to dislike Alan Heath's video.

Sign in to YouTube

Sign in with your Google Account (YouTube, Google+, Gmail, Orkut, Picasa, or Chrome) to add Alan Heath's video to your playlist.

Published on Mar 17, 2012

https://www.facebook.com/pages/Alan-H...

http://www.ceepackaging.com
twitter : @ceepackaging
https://www.facebook.com/pages/CEE-Pa...

The Double-crested Cormorant is a large waterbird with a stocky body, long neck, medium-sized tail, webbed feet and a medium sized hooked bill. It has a body length of between 70--90 cm, with a wingspan of between 114--123 cm Double-crested Cormorants weigh between 1.2--2.5 kg

This species has dark-colored plumage with bare super-loral skin and gular skin that is yellow or orange. An adult in breeding plumage will be mostly black with the back and coverts being a dark grayish towards the center. Nuptial crests, for which the species is named, are either white, black or a mix of the two. These are located just above the eyes with the bare skin on the face of a breeding adult being orange. A non-breeding adult will lack the crests and have more yellowish skin around the face. The bill of the adult is dark-coloured. The Double-crested Cormorant is very similar in appearance to the larger Great Cormorant, which has a more restricted distribution in North America, mainly on the Canadian maritime provinces; it can, however, be separated by having more yellow on the throat and the bill.

The plumage of juvenile Double-crested Cormorants is more dark grey or brownish. The underparts of a juvenile are lighter than the back with a pale throat and breast that darkens towards the belly. As a bird ages, its plumage will grow darker. The bill of a juvenile will be mostly orange or yellowish.

A very common and widespread species, it winters anywhere that is ice-free along both coasts, as far north as southern Alaska (on the west coast) and southern New England (on the east coast). It can be found as far south as Mexico and the Bahamas. It migrates from the coldest parts of its breeding range, such as eastern Canada, and has occurred in Europe as a very rare vagrant, for example in Great Britain, Ireland, and the Azores.

The Double-crested Cormorant swims low in the water, often with just its neck and head visible, and dives from the surface. It uses its feet for propulsion and is able to dive to a depth of 7.5 m for 30--70 seconds. After diving, it spends long periods standing with its wings outstretched to allow them to dry, since they are not fully waterproofed. This species flies low over the water, with its bill tilted slightly upward, sometimes leaving the colony in long, single-file lines.

Food can be found in the sea, freshwater lakes, and rivers. Like all cormorants, the double-crested dives to find its prey. It mainly eats fish, but will sometimes also eat amphibians and crustaceans. Fish are caught by diving under water. Smaller fish may be eaten while the bird is still beneath the surface but bigger prey is often brought to the surface before it is eaten. Cormorants regurgitate pellets containing undigested parts of their meals such as bones. These pellets can be dissected by biologists in order to discover what they ate.

Breeding occurs in coastal areas as well as near inland rivers and lakes. They build stick nests in trees, on cliff edges, or on the ground on suitable islands. They are gregarious birds usually found in colonies, often with other aquatic birds, and have a deep, guttural grunt call.

The Double-crested Cormorant's numbers decreased in the 1960s due to the effects of DDT. Colonies have also been persecuted from time to time in areas where they are thought to compete with human fishing.

Recently the population of Double-crested Cormorants has increased. Some studies have concluded that the recovery was allowed by the decrease of contaminants, particularly the discontinued use of DDT. The population may have also increased because of aquaculture ponds in its southern wintering grounds. The ponds favour good over-winter survival and growth.

Loading icon Loading...

Loading icon Loading...

Loading icon Loading...

The interactive transcript could not be loaded.

Loading icon Loading...

Loading icon Loading...

Ratings have been disabled for this video.
Rating is available when the video has been rented.
This feature is not available right now. Please try again later.

Loading icon Loading...

Loading...
Working...
to add this to Watch Later

Add to