INTRODUCTION:

The Mute Swan (Cygnus olor) is not altogether silent. It is called this because it does not emit sounds in flight, all other swans communicate in the air. On the water the Mute Swan is far from mute.

Due to the color of its plumage, it has also been called White Swan. It is not the only white swan, in the northern hemisphere there are four other swans with white plumage. If we were to include the Coscoroba, with most of its feathers white, then there are six white swans in total. But it is true that in the pond or the fountain, the Mute Swan is usually the only white swan we see.

In the United Kingdom, they are known to have bred in semi domesticated colonies since the 1700's. Not much later they were introduced to France and other countries in Europe where they established to more or less extend. Such an attractive waterfowl was the favorite of the royal ponds; until wars broke out and the swans disappeared from the gardens, and everywhere. Since them the Mute Swan has been reintroduced in many places and now once again it is a common sight in the ponds and lakes of Europe.

DISTRIBUTION:

The popularity of these swans has been such that it is hard to tell apart the wild populations from the reintroduced or escaped ones. Considered at least partially wild are the ones that breed in the northeast of Europe, the British Islands, southern Sweden, Denmark, The Netherlands, northern France, northern Germany, Poland, and countries south of the Baltic and Black Seas. In Asia, the same intermixing occurs, and although with much reservation, those that nest on the Caspian Sea and at irregular intervals throughout southern Siberia to the Baikal Lake and on Mongolia are considered natural or wild.

During winter part of the northern population moves south; many are sedentary and stay in the area where they breed, only moving to the coasts. The ones that migrate from Europe get together with some of the populations of the Black and Caspian Seas. In Asia they winter on the coast of the Yellow Sea and the Korea peninsula. Some of the youngsters of the year stay on the wintering zones until the next year when they return with the adults to the breeding regions.

Considered occasional on the rest of most of Europe, the Nile delta, Persian gulf, in Iran, from Afghanistan to India, Korea peninsula and Japan. The Mute Swan has been introduced in North America, Australia, New Zealand, South Africa and Japan.

STATUS:

In North America there are at least two strong populations in the northern United States, occasionally some of these are seen in southern Canada. Both populations have incremented reaching the thousands. The populations in Australia and New Zealand are estimated to be stable, not changing their numbers much. In Japan its numbers (estimated about 150 individuals) remain stable. The natural populations on the north of Europe and Asia are incrementing, estimated at more than half a million overall.

HABITAT:

This swan shows preference for lakes and rivers with shallow zones and banks or shores with tall grass. During winter they are seen on the estuaries and on brackish waters near the sea, on the sea coasts which offer some protection, and on the sea if the coast does not have protection; as when the coast freezes.

REPRODUCTION:

Usually, once the pair bonds it stays together for the rest of their life. Should one of them die, then the other is most likely to find a new mate. “Divorces” do occur when they are not successful at breeding, about 3% of the pairs separate. Some males are documented to have bred with two females at the same time; polygamy.

Normally they nests once a year. In captivity some pairs have nested twice in the same year and in the wild at least one case has been reported. Breeding season starts in spring; in March or April. The pair selects a site on the shores of a pond or lake or on the banks of a river. This territory is defended by the male against all trespassers, including last year youngsters. According to Sanders (1947) “[The Mute Swan] Can kill a dog and will attack a man or boat-load of people.” First the male pursues and bites the intruder until this one gets the message and leaves the area; otherwise the male swan will get on top of the intruder and drown him. The size of the territory varies according to the location. It is very usual for a pair to use the same nesting site for several years.

The nest is made on land next to water or on floating islands. Building materials include grass and twigs, arranged in the nest by the female. The structure could be six feet wide. In the depression at the center feathers and down are added.

The clutch could be from one to twelve eggs, the usual is from four to six. The eggs are greenish blue in color. One clutch can have eggs of different sizes. In a study the difference from the largest to the smallest was 32%; where the first egg was the smallest and the last the second smallest.

Incubation lasts from 35 to 38 days, some cases up to 41 days. The female usually takes care of the incubation, although some males have been seen replacing her. The cygnets are taken care by both parents. When they are small rather than swim they climb on the parents back, which is a common behavior among some of the swans and other aquatic birds. The youngsters stay with the parents for four to five months; in many cases until the beginning of the next breeding season.

In some places the females breed at the age of two years, usually paired to older males. Normally males do not start breeding until they are three years old. As expected, some individuals do not nest until they are older. On the average this swan starts breeding from four years (in England) to five years (in Ireland) of age.

LIFE SPAN:

In nature few live past 14 years, although some have surpassed 23 years of age.

FOOD:

For most of the year, the basic food of this swan is made up of aquatic plants from the bottom of ponds, lakes and rivers. While keeping at least part of the body above the surface it uses its long neck, to bite the leaves and stems of underwater vegetation. This diet is complemented with insects and frogs it catches. In some places, in winter and spring, usually starting in December, it visits the crop fields where it feeds on seeds.

DESCRIPTION:

This is the second biggest swan; the Trumpeter Swan is somewhat bigger. Both sexes are alike. Males are slightly bigger, reaching a wing span of seven feet. The black thickening on top of the beak usually grows bigger on the males, but this is not a reliable indication to tell the sexes apart.

Some figures for wild and semi domesticated (captive or farm Mute Swans could exceed some of these figures):
Adult males:
   average length of 1.53 meters (about 5 feet);
   weight: 8.4 to 15.0 Kg. (18.5 to 33 lbs), average: 10.5 to 11 Kg. (23 to 25 lbs);
   bill from 76 to 88 mm;
   wing from 589 to 623 mm.
Adult females:
   average length of 1.27 meters (about 4 feet);
   weight: 6.6 to 12.0 Kg. (14.5 to 26 lbs), average 8.4 to 9.5 Kg. (18.5 to 21 lbs);
   bill from 69 to 50 mm;
   wing from 533 to 596 mm.
Cygnets:
   average weight day after hatching is 215 grams (180 to 248 grams).
Eggs:
   average size is 114 by 73 mm (97 to 124 by from 69 to 80 mm)
   average volume of 321.1 cubic centimeters (187 to 469 cubic cm)
   average weight of 340 grams (258 to 500+ grams).

IDENTIFICATION:

It can be identified by its orange to red beak; all other northern white swans have yellow and/or black beaks. It is also the only white swan with a black thickening on top of the beak.

SOUNDS:

As per Sandars (1947): “Soft low notes when pairing. Pen, angry hissing when disturbed. Cob, defiant grunt when guarding nest.” Just like cygnet is the name given to the swan chick, pen is the name given to the female swans and cob is how the male swans are called.

MOLT:

As other swans, the Mute Swan molts once a year. During this time, from four to six weeks, it cannot fly, all flight feathers are molted together. Male and female adults that did not breed, and juveniles, start molting from early June to early August. For the Mute Swan these are the most food abundant months. The breeding females start to molt later, from mid June to mid August. There is the theory that this delay is related to their loss of weight during incubation (about 2.8 Kg.), needing a month after the cygnets hatch to recover. Another theory is based on the care of the cygnets. The breeding males are the last to molt, starting from mid July to mid September. When these males start molting the cygnets are almost their size. In this case there is more agreement that this delay is for the benefit of the youngsters.

THREATS:

Among the mortality causes of the Mute Swan are: oil contamination, lead poisoning, struck by cars, parasites, fishing nylons and hooks, dogs, foxes and illegal hunters. In males, territory defense is responsible for many losses. Still, under normal circumstances, the one cause that takes more lives than all the others put together is hitting permanent objects during flight (towers, electric wires, bridges, etc.).

OTHER NAMES:

The Mute Swan (Cygnus olor) is also known as “White Swan”. In Spanish is called “Cisne Vulgar”, “Cisne Común”, “Cisne Mudo” and “Cisne Blanco”; in German: “Höckerschwan”; in French: “Cygne muet” and “Cygne tuberculé”.