Lead poisonings most unheard of victim - the mute swan.

-
Mute swan.


Mute swan.
On campus there are a few mute swans that can be seen on the lake. The scientific name for the mute swan is Cygnus olor and they are in the bird family ducks, geese and swans. As all UK birds they are protected under The Wildlife and Countryside Act of 1981 but this hasn't protected them completely and thus them having an amber UK conservation status. They are very large white waterbirds and are easily recognisable by their long S-shaped neck and orange bill. Protection of the species has increased recently meaning their numbers have begun to increase again. Lead poisoning on lowland rivers was one of the largest threats to swans but in recent years this has been overcome by a ban on lead fishing weights. There are around 6,400 breeding pairs in the UK and 74,000 UK wintering individual birds. Swans are large birds weighing up to 12 kg and having a wing span of over 2 meters.

The main diet of a mute swan includes aquatic vegetation which they can easily pick up from river beds due to their long necks. They are also known to eat small fish, worms and even frogs. They don't always need to be in aquatic environments to survive and they are more than happy to feed in grassy fields and can survive in afield of short-cropped grass. It is a common belief that feeding swans and ducks bread is good for them but on a large scale it can cause them dietary problems so should be avoided.
A courting display with two mute swans. http://www.bbc.com/earth/story/20141204-the-truth-about-swans

Cygnets and their mother. First-cygnet_1395980c.jpg
Male swans are called cobs and females are called pens. Swans aim to mate for life in most circumstances unless one of the pair die. During courting, mute swans have been seen to make a heart shape out of their necks.Nests are made during the breeding period and look like a massive mound of material. Constructed at the waters edge, their nests are made of lots of different vegetation and dried grasses, sticks and also rushes. The cob and the pen work as a team to construct the nests as the cob will provide the supplies to create the nest whilst the pen builds it. Pens can lay up to 7 eggs anytime between the end of April and the start of May. Once the eggs have been laid, both the cob and the pen incubate the eggs until they hatch after about 35 days. Cygnets, baby swans, are known to ride on their parents backs as a form of transport and don't leave their parents until they are over 4 months old. Cygnets present differently to adult mute swans as they are grey-brown with a white belly. Young birds don't tend to breed for the first 2 years of their lives.

Swans have many predators including foxes which take roosting birds that are in easy to reach places. However, predators are not the main threat to swans. Pollution of freshwater areas is the biggest threat swans face. In order to break down food, swans require grit in their stomach. Whilst taking in this grit the swan may inadvertently take in some lead fishing equipment that anglers used as weights before they were banned called shots. Once the shot is in the gizzard of the swan it is slowly absorbed into their bodies and can lead to lead poisoning. Swans can also get caught in fishing tackle or swallow the hooks meant to catch fish. Fishers need to make sure they are not using lead products, which they shouldn't be as it is not illegal, and make sure they don't leave any of their equipment behind as swans are the ones paying the price.

















Comments

Post a Comment

Popular posts from this blog

Monogamy, polyandry, polygyny and polygynandry; are dunnocks the most promiscuous bird?

-
Image
A dunnock having its health observed during a bird ringing session. These beautifully understated birds weigh roughly the same as a 'AA' battery (24 g) and are the same length as two and a half golf tees (14 cm). The dunnock, Prunella modularis are in the bird family accentors and have an amber UK conservation status even though they are protected under The Wildlife and Countryside Act. They are very quiet and unobtrusive birds and are usually seen along flower bed edges or near to bushes. They move in a shuffling gait and come across quite nervy until two rival males meet and then they become very animated and aggressive. Their colouring is quite simple as they are just brown and grey. A dunnock on the look out.  Dunnock-min.jpg Dunnocks have gone through many adaptions in order to use different breeding strategies. Females mate with more than one male in order to make sure her genes are passed onto the next generation and in hope that they will both help rear her c...
Read more

Growing populations mean issues for ducks.

-
Image
A female mallard. There are many species of ducks that inhabit the UK including mallards, mandarins and long-tailed ducks. The scientific name for the mallard is Anas platrhynchos and they are in the ducks, geese and swans bird family. Their UK conservation status is amber meaning they are under concern but they are protected under The Wildlife and Countryside Act 1981. The males of the species look different to the females of the species meaning they are sexually dimorphic. Male mallards are more colourful than females and have distinctive green heads and yellow beaks. Females are all brown compared to males who have white bodies. They are usually around 60 cm in length and have a wingspan of 81-98 cm. There are between 61,000-146,000 breeding pairs in the UK. A male mallard being followed by a female. There is a close link between food and number of mallards. If there is a lot of food resources in a pond then there will be a lot of mallards but this can lead to overpopulati...
Read more