Monday, 4 January 2021

Red-breasted merganser

 


The red-breasted merganser (Mergus serrator) is one of only two species of sawbill duck (the other being the goosander) that breeds in the British Isles. The red-breasted merganser has a long history of residence in Scotland and Ireland. However, since about 1950 they have spread into England, breeding as far south as Derbyshire and also into Wales.

Red-breasted mergansers grow to around 23 inches (58 cm) in length. Adult males have dark green heads and reddish-brown breasts and necks. The head has a double crest. Females are brown on the head and neck, the colouring merging into the breast. Their white wing patches are most noticeable in flight.

Flight is fast and direct, with the neck and body outstretched to produce a long, narrow shape.

The term ‘sawbill’ refers to the finely serrated cutting edges on the bills that enable red-breasted mergansers to grasp slippery fish. When fishing, they often swim with the head under water before diving to catch their prey.

Red-breasted mergansers have suffered persecution in the past due to their liking for young trout and salmon. However, they also eat species including eels, perch and pike which prey on the eggs and young of salmon and trout.

The nest is a shallow depression in the ground, lined with grass, leaves and down, that is sited near a river or lake and often in thick vegetation which makes it difficult for a predator to find. From late April to early July the female lays and incubates 8 to 10 eggs that take a month to hatch. When she leaves the nest to feed, she camouflages the eggs with down. When hatched, the ducklings are attended to by the female on her own. They can fly around two months after they hatch. Only one brood is reared each year.


© John Welford

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