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May 2014

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Mayfly habitat, Sheila Sims
Mayfly habitat, Sheila Sims

Mayflies are so called because this is the month when they take to the air to find a mate. There are over 2,000 species and they are found everywhere in the world except the Antarctic, the Arctic and some islands; our watery county provides an ideal habitat. The adult life of these insects is very short, some having less than an hour to mate and lay their eggs and they do not eat during this phase. The males will form a swarm over water and the female will fly in amongst them, to be grabbed by a male with his long front legs, then they mate in mid-air. She drops on to the surface of the water, lays her eggs and then, completely worn out, floats until she dies; the males usually die on nearby land.

This is feasting time for fish which gorge themselves on the helpless flies. The Mayflyies’ eggs fall to the bottom and stick to stones or plants and will take anything from a few days to several weeks, depending on the species and the condition of the water, to hatch into the first stage of their lives, called nymphs. Some burrow, some crawl and others are free swimming; they feed on organic debris but some are also carnivorous and hunt small water creatures. This is how the greater part of the Mayfly’s life is spent, sometimes up to two years will pass before it is ready to emerge from the water as an adult. When the time comes the nymph will rise to the surface, pull itself free from its skin and shelter in bankside vegetation. This first adult stage is  known as a sub-imago, or dun, and after a few minutes to a couple of hours, it will again moult and become the second adult stage. This is called the imago, or spinner, which is the shiny fly we see over the water; the Mayfly is unique among these type of insects in having two adult forms, both winged. They are now ready to start the whole procedure again; they are mainly nocturnal, so we will see them at dawn and dusk.

Chinese Water Deer start to give birth later this month and they will  hide their spotted fawns well away from the sight of potential predators and human eyes. Never the less, there is a high mortality rate, sometimes due to bad weather or disease, and sometimes foxes will find them.

Little Egret, Joan Dixon
Little Egret, Joan Dixon

A Little Egret has visited Briggate Mill Pond, near North Walsham, again this year and these small, white herons now breed in Norfolk; they are regular visitors to Titchwell, Holkham and Cley. Although there is still some disruption after the floods, the hides at Cley are now all open.

A nest has been built by a pair of White Storks at Thrigby Hall Wildlife Gardens, near Great Yarmouth. These are not wild birds but, unlike the other storks in the bird collection there, they have not had their flight feathers removed from one wing, so are able to fly freely. Although storks have bred before in Britain, in zoos, this is the first pair, for 600 years, to nest naturally and the news has had national coverage.  It will be interesting to see whether or not they will migrate to Africa for the winter, like the wild birds that breed in Europe. Meanwhile, the young are eagerly awaited and, of course, they will be delivered in a knotted nappy by another stork. (You know they will)!

Since emerging from hibernation, slow-worms have been busy getting into good bodily condition ready for breeding this month. These animals measure 40 – 45 cm (16 – 18 in) in length and are often mistaken for small snakes but they are, in fact, legless lizards. Unlike snakes they have eyelids, external ears and their tails are blunter. The female is a gold-coppery colour with a dark vertical stripe down her back, while the male will be grey, bronze, brick red or dark brown, sometimes with blue spots. They inhabit woodland, heathland, railway embankments, allotments and gardens where they will be hunting small, soft invertebrates such as spiders, worms and slugs. After the female has mated the young take 4 – 5 months to develop inside her body and are born in late August to early September, when they arrive in egg membranes which rupture almost immediately.

Slow-wormSheila Sims

Slow-worm, Sheila Sims
Slow-worm, Sheila Sims

The young are small, about 70 – 100 mm (2 3/4 – 4 inches) and are pale gold or silvery-grey, with a dark stripe down the back; the males will lose this when they are mature, usually at about three years of age. Twenty six young have been recorded in a single litter but the average is eight and they are independent as soon as they are born. Slow-worms forage in warm, damp places and will often hide under stones and logs, also compost heaps and corrugated metal sheets that retain the heat of the sun. Many animals prey on them including foxes, badgers, cats, hedgehogs, snakes and some birds; the young are particularly at risk. Like other lizards, they have the ability to spontaneously shed their tails when grasped and this will keep moving and act as a distraction to the predator; the tail will regrow but will have a blunter end than before.

Slow-worms hibernate, often underground, from October until March when they will emerge and bask in the sun. Like all reptiles they are cold-blooded and need to acquire their bodily heat from an outside source. They are harmless creatures and good to have in the garden as they will feed on the slugs that destroy our plants. As a child I was an avid collector of all sorts of animals, much to my Mother’s dismay, and slow-worms often featured in my menagerie. They were great escape artists and sometimes made their way into neighbours’ gardens. The panic stricken cry ‘A snake! A snake!’ would tell me that my runaway had been found. I was not a popular child!

As a follow up to last month, if you did happen to see an Osprey flying through Norfolk, it could have been a 29 year old bird called Lady, which has laid her 69th egg at a Perthshire nature reserve; she has reared 50 chicks there over 24 consecutive years.

Events to take part in this month include:-
• Dawn chorus & breakfast.
• Fabulous Wildlife walks – both at Titchwell marsh. 01485-210779.
• Guided walks & Pinewoods discovery – both at Holkham Nature Reserve. 01328-710227 or
• Spring passage birds – Cley Marshes.
• Go Wild! Includes boat trips and (yes, I mean it!) worm charming.01603-625540 or