Mute Swan
Cygnus olor
Summary 3
The mute swan (Cygnus olor) is a species of swan and a member of the waterfowl family Anatidae. It is native to much of Eurosiberia, and (as a rare winter visitor) the far north of Africa. It is an introduced species in North America – home to the largest populations outside of its native range – with additional smaller introductions in Australasia and southern Africa. The name 'mute' derives from it being less vocal than other swan species. Measuring 125 to 170 cm (49 to 67 in) in length, this large swan is wholly white in plumage with an orange beak bordered with black. It is recognisable by its pronounced knob atop the beak, which is larger in males.
Description 4
Adults of this large swan typically range from 140 to 160 cm (55 to 63 in) long, although can range in extreme cases from 125 to 170 cm (49 to 67 in), with a 200 to 240 cm (79 to 94 in) wingspan. Males are larger than females and have a larger knob on their bill. On average, this is the second largest waterfowl species after the trumpeter swan, although male mute swans can easily match or even exceed a male trumpeter in mass. Among standard measurements of the mute swan, the wing chord measures 53–62.3 cm (20.9–24.5 in), the tarsus is 10–11.8 cm (3.9–4.6 in) and the bill is 6.9–9 cm (2.7–3.5 in).
The mute swan is one of the heaviest flying birds. In several studies from Great Britain, males (known as cobs) were found to average from about 10.6 to 11.87 kg (23.4 to 26.2 lb), with a weight range of 9.2–14.3 kg (20–32 lb) while the slightly smaller females (known as pens) averaged about 8.5 to 9.67 kg (18.7 to 21.3 lb), with a weight range of 7.6–10.6 kg (17–23 lb). While the top normal weight for a big cob is roughly 15 kg (33 lb), one unusually big Polish cob weighed almost 23 kg (51 lb) and this counts as the largest weight ever verified for a flying bird, although it has been questioned whether this heavyweight could still take flight.
Young birds, called cygnets, are not the bright white of mature adults, and their bill is dull greyish-black, not orange, for the first year. The down may range from pure white to grey to buff, with grey/buff the most common. The white cygnets have a leucistic gene. Cygnets grow quickly, reaching a size close to their adult size in approximately three months after hatching. Cygnets typically retain their grey feathers until they are at least one year old, with the down on their wings having been replaced by flight feathers earlier that year.
All mute swans are white at maturity, though the feathers (particularly on the head and neck) are often stained orange-brown by iron and tannins in the water.
The morphimmutabilis (immūtābilis is Latin for "immutable, unchangeable, unalterable"), also known as "Polish swan", has pinkish (not dark grey) legs and dull white cygnets; as with white domestic geese, it is only found in populations with a history of domestication. Polish swans carry a copy of a gene responsible for leucism.
North America 4
The mute swan was introduced to North America in the late 19th century. Recently, it has been widely viewed as an invasive species because of its rapidly increasing numbers and its adverse effects on other waterfowl and native ecosystems. For example, a study of population sizes in the lower Great Lakes from 1971 to 2000 found that mute swan numbers were increasing at an average rate of at least 10% per year, doubling the population every seven to eight years. Several studies have concluded that mute swans severely reduce densities of submerged vegetation where they occur.
In 2003, the U.S. Fish and Wildlife Service proposed to "minimize environmental damages attributed to Mute Swans" by reducing their numbers in the Atlantic Flyway to pre-1986 levels, a 67% reduction at the time. According to a report published in the Federal Register of 2003 the proposal was supported by all thirteen state wildlife agencies which submitted comments, as well as by 43 bird conservation, wildlife conservation and wildlife management organisations. Ten animal rights organisations and the vast majority of comments from individuals were opposed. At this time mute swans were protected under the Migratory Bird Treaty Act due to a court order, but in 2005 the United States Department of the Interior officially declared them a non-native, unprotected species. Mute swans are protected in some areas of the U.S. by local laws, as for example in Connecticut.
The status of the mute swan as an introduced species in North America is disputed by the interest group "Save the Mute Swans". They assert that mute swans are native in the region and therefore deserving of protection. They claim that mute swans had origins from Russia and cite historical sightings and fossil records. These claims have been rejected as specious by the U.S. Department of the Interior.
Sources and Credits
- (c) Bengt Nyman, some rights reserved (CC BY), https://www.flickr.com/photos/bnsd/34003204480/
- (c) Bill MacIndewar, some rights reserved (CC BY-NC), uploaded by Bill MacIndewar
- (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Cygnus_olor
- (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Mute_swan
