Red-breasted Merganser (Kluane National Park and Reserve of Canada | Parc national et réserve de parc national du Canada Kluane)

Red-breasted Merganser

Mergus serrator

Physical description ³

Red-breasted mergansers are large diving ducks with long, thin bills lined with serrated edges to help in capturing fish prey. Males are larger than females. Lengths range from 51 to 64 cm and weights from 800 to 1350 g. In their breeding plumage, males are more colorful, with dark greenish heads, a white collar, brown-speckled breasts, steel-gray flanks, and greenish-black backs that are bordered by a white patch. Both females and males have a double crest of plumes at the back of their heads. Females are grayish brown, with a small, white wing bar, a whitish breast with gray speckles, and the feathers on the head are reddish brown. The bill and legs are reddish-orange and the bill has a black tip. Females stays the same throughout the year and immature birds resemble females. Males in the non-breeding season resemble females but have wider, white wing bars.

Associations ⁴

Red-breasted mergansers are important predators of small fish in their wetland habitats. Several bird species take advantage of the fact that red-breasted mergansers will herd fish prey to the water's surface when they are foraging. Snowy egrets, Bonaparte's, and ring-billed gulls will wait at the surface to grab fish scared by merganser foraging. Red-breasted mergansers are also attracted to areas where gulls are feeding on schooling fish.

Food habits ⁵

Red-breasted mergansers eat mainly small Actinopterygii (10 to 15 cm long) and Crustacea. Their diet is usually made up of more than 75% small fish, with less than 25% made up of crustaceans and other aquatic animals, including insects, worms, and amphibians. They seem to prefer foraging in shallow water, but they will hunt wherever prey is abundant. Red-breasted mergansers forage in several different ways. They float at the surface, looking underwater as they go, they dive in deep or shallow water to search for prey, or they dive in formation with other red-breasted mergansers to herd schooling prey. Preferred fish prey include Fundulus, Gasterosteidae, Salmo salar, Cottus, Clupea pallasi and their eggs, Oncorhynchus, Menidia menidia, and Alosa aestevalis.

Conservation status ⁶

Red-breasted mergansers have a wide distribution and large populations, they are not considered currently threatened. However, some populations may be threatened by wetland destruction and contamination by pesticides and lead. They are also captured in fishing nets fairly frequently.

IUCN Red List of Threatened Species: least concern

Sources and Credits

(c) Robert Keereweer, some rights reserved (CC BY-NC), http://www.flickr.com/photos/7261670@N03/2398614793
(c) BiteYourBum.Com Photography, some rights reserved (CC BY-NC-ND), https://www.flickr.com/photos/biteyourbum/8300260390/
(c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/25065644
(c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/31405870
Adapted by L.G. Johanson from a work by (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/25065648
Adapted by L.G. Johanson from a work by (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/31405873

More Info

Range Map

iNaturalist.ca Map

Animal	Bird
Bird	Ducks Geese & Swans (Anatidae)
Color	brown, green, grey, red

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