Barrow's goldeneye

Barrow's goldeneye
Male
Immature, female
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Superorder: Galloanserae
Order: Anseriformes
Family: Anatidae
Subfamily: Merginae
Genus: Bucephala
Species: B. islandica
Binomial name
Bucephala islandica
(Gmelin, 1789)

Barrow's goldeneye (Bucephala islandica) is a medium-sized sea duck of the genus Bucephala, the goldeneyes. This bird was named after Sir John Barrow. The genus name is derived from Ancient Greek boukephalos, "bullheaded", from bous, "bull " and kephale, "head", a reference to the bulbous head shape of the bufflehead. The species name islandica means Iceland.[2]

Description

Adults are similar in appearance to the common goldeneye. On average, adult males are 48.8 centimeters (19.2 inches) long and weigh 1.0 kilograms (2.13 lb); females are typically 43.2 centimeters (17.0 inches) long and weigh 0.6 kilograms (1.31 pounds).[3] Adult males have a dark head with a purplish gloss and a white crescent at the front of the face. Adult females have a mostly yellow bill. The male Barrow's goldeneye differs from the male common goldeneye in the fact that the common goldeneye has a round white patches on the face, less black on the back of the bird, and a larger bill. For the females, the common goldeneye has a less rounded head, and a bill in which only the tip is yellow.[4]

Vocalizations

The Barrow's goldeneye is a relatively quiet bird that generally only makes vocalizations during the breeding season and courtship. These can include low volume squeaks, grunts and croaks. During flights, the fast movement of the bird's wings creates a low whistling sound.[5]

Range and habitat

Their breeding habitat consists of wooded lakes and ponds primarily in northwestern North America, but also in scattered locations in eastern Canada and Iceland. Females return to the same breeding sites year after year and also tend to use the same nesting sites. The males stay with their mate through the winter and defend their territory during the breeding season, then leave for the molting site. Mating pairs often stay intact even though the male and female are apart for long periods of time over the summer during molting times. The pair then reunites at wintering areas.[6]

In Icelandic the bird is known as húsönd (house-duck); it is a common species of the Lake Mývatn in the north of the country.

Behavior

They are migratory and most winter in protected coastal waters or open inland waters. Barrow's goldeneye, along with many other species of sea ducks, rely on urbanized, coastal estuaries as important places on their migration patterns. These estuaries provide excellent wintering and stopping places during the ducks' migration.[7] It is an extremely rare vagrant to western Europe and to southern North America.[8]

These diving birds forage underwater. They eat aquatic insects, crustaceans and pond vegetation. The main staples of the bird's diet are Gammarus oceanicus and Calliopus laeviusculus, which are both marine crustaceans. A large part of their diet consists of mussels and gastropods.[9]

The Barrow's goldeneye is considered an arboreal bird species because much of its nesting is done in cavities found in mature trees. The birds will also nest in burrows or protected sites on the ground.[10] Barrow's goldeneyes tend not to share habitat with the much more numerous common goldeneye. Barrow's goldeneye tend to be territorial towards other birds venturing into their domain. This is especially true among the drakes. Confrontations may occur in the form of fighting. Drakes often do a form of territorial display along the boundaries of their territory. This is both true on land and in the water. These territorial displays average about 6 minutes in length and often trigger other males to perform their own show.[11]

Reproduction

Egg, Collection Museum Wiesbaden

Very little is known about the breeding sites and patterns of the Barrow's goldeneye. After the breeding season, the birds migrate to specific molting sites to undergo molting, the loss and regeneration of feathers which causes them to be flightless for anywhere from 20–40 days. These molting sites are often wetlands that are more drought resistant and plentiful in food, along with being less influenced by humans and predators.[12]

1989 Exxon Valdez oil spill

The Barrow's goldeneye was greatly affected by the Exxon Valdez oil spill in 1989. The spill greatly impacted the bird's wintering areas, and numbers of the birds in these areas decreased after the spill. The birds' exposure to the oil spill mainly occurred in the shallow water mussel beds along the coast.[13]

Gallery

References

  1. ↑ BirdLife International (2012). "Bucephala islandica". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
  2. ↑ Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp. 38, 79. ISBN 978-1-4081-2501-4.
  3. ↑ Ducks Unlimited. (n.d.) Barrow’s goldeneye. https://www.ducks.org/hunting/waterfowl-id/barrows-[] goldeneye#ad-image-0
  4. ↑ The Cornell Lab of Ornithology. (n.d.) Barrow’s goldeneye. All About Birds. http://www.allaboutbirds.org/guide/Barrows_Goldeneye/id
  5. ↑ Mayntz, M. (n.d.). Barrow’s goldeneye. About.com Birding/Wild Birds. http://birding.about.com/od/Waterfowl/fl/Barrows-Goldeneye.htm
  6. ↑ Savard, J-P. L. (1985). Evidence of long-term pair bonds in barrow’s goldeneye (bucephala islandica). The Auk, 102(2), 389-391
  7. ↑ De La Cruz, S. (2014) Resource selection and space use by sea ducks during the non-breeding season: Implications for habitat conservation planning in urbanized estuaries. Biological Conservation. 169. 68-78
  8. ↑ Littlejohn, Chase (1916). "Some unusual records for San Mateo County, California. Abstract in: Minutes of Cooper Club Meetings" (PDF). Condor. 18 (1): 38–40. doi:10.2307/1362896.
  9. ↑ Bourget, D. (2007). Distribution, diet and dive behavior of barrow's and common goldeneyes during spring and autumn in the st. lawrence estuary. Waterbirds: The International Journal of Waterbird Biology, 30(2), 230-240.
  10. ↑ Boreal Songbird Initiative (2007). Selected birds of the boreal forests of north america barrow’s goldeneye. http://www.borealbirds.org/birdguide/bd0409_species.shtml
  11. ↑ Savard, J-P. L. (1984). Territorial behaviour of common goldeneye, barrow’s goldeneye and bufflehead in areas of sympatry. Ornis Scandinavia, 15(4), 211-216.
  12. ↑ Hogan, D. (2011). Discovery of important post breeding sites for barrow’s goldeneye in the boreal transition zone o alberta. Waterbirds, 34(3), 261-268
  13. ↑ Peterson, C. H. (2003). Long-term ecosystem response to exxon valdez oil spill. Science, 302(5653), 2082-2086

External links

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