Conservation diary: Swan song

mike newby

Mike Newby is Estate Warden at The Dartington Hall Trust. He oversees Dartington’s numerous conservation programmes, often working closely with our volunteers to help nature flourish across the estate.

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The most commonly sighted white swan in the British Isles, and around the Dartington estate, is the mute swan.

Mute swans do not migrate and are a permanent resident all year round, unlike the Bewick and Whooper swans who are winter visitors to these shores.

Mute swan
Mute swan

The male swan is called a cob and a female is called a pen and group of swans is called a herd. Swans are highly intelligent and sharp vision and impeccable hearing.

A mute swan has 23 vertebrae more than any other bird. There three signs to determine the difference between a pen from a cob: pens tends to be larger in stature, the knob on the base of the upper bill is bigger than the female and the male has a thicker neck.

The average life span of a swan would be around 12 years. There are many hazards for a swan to contend with throughout their lives such as foxes, mink, dogs, vandals, bridges, overhead cables, lead poisoning, fishing tackle injuries etc. However, in a protected environment like a nature reserve a swan can reach a ripe old age of 30.

In the months of July or August swans tend to moult each year. During this period they are unable to fly for roughly six weeks from the time they lose their flight feathers and until they grow new ones. They have approximately around 25,000 feathers.

Swans are able to take off from the land but requires at least 30 yards to become airborne and another 30 yards to reach a safe height to miss obstacles like buildings or power lines.

It is a misconception that swans will bite you as they have no teeth but will hiss and peck at you which will cause you some discomfort to the skin.

Swans that live on fresh water will typically feed on pond weed, stonewort and some grasses along with tadpoles and insects. The diet of swan who resides on salt water is slightly different and includes salt marsh grass, rushes, sea arrow grass as well as insects and molluscs.

If you are going to feed swans do not feed them bread – especially mouldy bread as it is poisonous to them and are unable to break it down. Wild birds tend to have enough food in their natural environment but you could feed them spinach, lettuce and grain such as corn or wheat.

The food should be thrown onto the water so it can be digested with the water. It is advised not to feed the swans on land as it brings them into harm’s way from dogs etc.

Swans are not greedy animals and will only eat what they need. Often you will see a swan fold one its legs back onto its back, which is similar to a person crossing their legs. The large surface area of the foot is used to regulate the body temperature like an elephant’s ear which absorbs heat from the sun when required.

Swans build their nests beside watercourses or on islands. The nest usually takes 2-3 weeks to complete. Then the egg laying begins with an egg being laid approximately every day. Once all the eggs have been laid which can take up to around 3 weeks. The female will then sit on the eggs and hatching will occur over this 6 week period. Usually swans hatch up to 10 eggs at a time with the expectancy of losing some of them.

Sometimes a swan may sit on her eggs longer than the 6 week incubation period due to the female still hearing movement within inside the eggs. Also it could be possible that she may have lost her initial clutch to a predator and has laid a fresh batch of eggs.

If the female is predated or disappears, the male will proceed with the nesting process and is able to rear the cygnets alone. The same applies to the male being predated and the female is capable of rearing the cygnets herself.

An obvious sign of a fox attack on a swan is clear, as it tends to remove the whole of neck leaving the body behind. Young and new born cygnets are vulnerable to predation. Mainly new born cygnets are taken by; magpies, crows, herons, pike and perch. Mink and foxes are also known predators of cygnets and swans.

The adult swans are not frightened of leaving the nest in search for food. This is because they tend to feast before nesting commences as they know food will become harder to find once they are on the nest. During this period it is normal for them to lose weight.

Mating Swans
Mating Swans

Swans will breed throughout their lives which slowly decreases the older they become. Cygnets remain with their parents for about 6 months. When the cygnets are mature enough to fend for themselves. The parents cut their ties from them and chase them, on occasion quite forcefully.

A juvenile swan usually lives as part of a herd until it is about 4 years old and deemed to be an adult. Then it seeks out a mate, most often than not from the flock it is living in and heads off with mate to locate their own mating territory. A territorial battle will commence if another mating pair are close by and the loser will have to move to another suitable area to mate. The defender of the territory will try and drown its challenger.

Swans have a unique mating ritual by elegantly touching one and others bills very delicately. They also cuddle close to form a heart shape with both their breasts pressed firmly together.

Mike

 


 

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