Common Pochard

The common pochard is a plump, medium-sized diving duck, measuring 42–49 cm (17–19 in) in length, with a wingspan of 72–82 cm (28–32 in). It is stocky and short-tailed, with a sloping forehead and relatively long bill. Its weight (which has been reported only for winter birds) ranges from 467 to 1,240 g (16.5 to 43.7 oz). Males average larger and heavier than females. Like most ducks, it is sexually dimorphic. The male has a chestnut-coloured head and neck, a black breast and tail, and a pale grey body, marked with fine vermiculations. His bill is dark grey, with a wide blue-grey band across the middle. His iris is yellow-orange to red, growing brighter in the breeding season. The legs and feet are grey in both sexes and all ages. The female's iris is brown, sometimes tending towards yellowish-brown. The juvenile's iris is yellow-olive, but attains its adult colour during the first winter.

Voice. The male is generally silent, though he may whistle softly as part of his courtship display. The female growls softly—a sound transcribed as krrr—if she is flushed. The duckling has a short contact call of two to four notes. If distressed, its calls are higher and faster than are those of Anas ducklings of the same size and age.

Similar species. The male common pochard is quite similar to the male canvasback, but the latter has an all-dark bill. …

Their breeding habitat consists of marshes and lakes with a metre or more water depth. Pochards breed in much of temperate and northern Europe and across the Palearctic. They are migratory, and spend winter in the south and west of Europe. In the British Isles, birds breed in eastern England and lowland Scotland, in small numbers in Northern Ireland with numbers increasing gradually, and sporadically in the Republic of Ireland, where it may also be increasing. While uncommon, individuals are also occasionally seen in the south of England, and small populations are sometimes observed on the River Thames. Large numbers stay overwinter in Great Britain, after the birds retreat from Russia and Scandinavia. Common pochards have been seen as vagrants in North America, especially in the United States and Canada. In South America, a record of the species exists from Colombia.

These are gregarious birds; they form large flocks in winter, often mixing with other species of diving duck. They are strong fliers; in direct, flapping flight, they can reach speeds of 22–24 m/s (49–54 mph).

Food and feeding. Common pochards feed on plant material (including seeds), small fish, molluscs, and other aquatic invertebrates. They feed primarily by diving to retrieve items from under the water's surface; however, they will also upend and dabble at items on the water's surface. They do most of their feeding at night. They regularly forage in close association with Bewick's and whooper swans, two species that trample underwater sediment to excavate food. Studies have shown that this behaviour greatly increases the food intake rate of the pochards, as they glean food items that drift away from where the swans are trampling. This rate can be double what it would be if the birds were feeding on their own.

Breeding. The female builds a platform nest of plant material, with a shallow cup lined with down feathers near its centre. This is placed either on the ground within 10 m (33 ft) of the water's edge or in the water with the platform rising above the water's surface. It is always located in dense cover. The female lays one egg daily until her clutch—typically 8–10 eggs—is complete. Only then does she begin incubation. …