Rainbows must be near the top of the list of nature’s spectacular sights; who doesn’t stop and look when one appears. But a rainbow is not really there, it is an optical phenomenon that can only be seen if you are in the right place. Also the sun has to be behind you and there have to be water droplets in the air. Sunlight is made up of many wavelengths of light and these are coloured. When they are all together we see them as white light but when the sunlight passes through a rain drop it bends and splits the light back into the colours red, orange, yellow, green, blue, indigo and violet, reflecting them in the sky to create a rainbow. There is a phrase, a mnemonic, used to remember the order of these colours, ‘Richard of York gave battle in vain’. Sometimes there is a secondary bow which will be fainter with the colours reversed; occasionally we see even more bows. What must prehistoric man have made of rainbows. Certainly there are many legends attached to them. Some ancient people looked upon them as omens of disaster but some thought of them in a more kindly way. Ancient Polynesians thought they were ladders for heroes to climb up to heaven and Greek folklore taught that Iris, the wife of the god Zephyrus, caused rainbows. She was the messenger between the gods and mortals and wore a shimmering, multi-coloured dress which we see as she runs back and forth delivering her messages; the word ‘iridescence’ comes from the description of her dress.
I am sorry to say that I made an angler rather angry last month about lead poisoning in swans. As he quite rightly pointed out lead weights on fishing lines are banned in this country but some countries passed through by migratory birds still allow them and this is where the swans pick them up; I am happy to make this clear. As far as shooting goes, although lead shot is banned over wetlands, I’m afraid that compliance does seem to be rather patchy. A high percentage of Mallards examined at game dealers contained lead and as these birds are shot in wetland habitats it means that the law, which is difficult to enforce, is being flouted. Mallards are dabbling ducks, and will also take in scattered shot when feeding in shallow water. Lead shot is allowed when shooting over farmland and other habitats and many birds feed in these places; the shot is ingested when they mistake it for food or for grit which they need for their digestion.
Mallards are omnivorous and as well as feeding on plants will also take snails, worms, crustaceans and aquatic insects. One that features in their diet is the larvae of the Caddis fly of which there are almost 200 species in Britain. Most have clever aquatic larvae which build themselves mobile homes. They will gather available materials which they bind together with silk produced from glands around their mouths. Some of these protective cases are composed of grains of sand, some are made from pieces of plants and some from bits of snail shells; they are little works of art. The larva eats a variety of foods, both plant and animal and when it has completed this first stage of its life it cements its case to a solid object and, like a butterfly or moth – it is closely related to these – it pupates inside. When the pupa is ready to turn into an adult fly it will float to the surface and a new Caddis fly will emerge. At this stage of their lives they are very vulnerable to predation and many are taken by fish and birds or, if they emerge at night, by bats.
Another animal that would take emerging Caddis flies is the Terrapin. The release of more Teenage Mutant Ninja Turtle films encouraged a resurgence of the 1980’s craze of buying baby terrapins to keep as pets. However, as we have talked about before, they can grow to be the size of dinner plates and then they are not so cute. Consequently more are thought to have been released into British waterways where they survive very well. Our Norfolk Broads provide an ideal habitat for these animals and they have been seen basking on banks on warm, sunny days.
Sue, from North Walsham, sent me some photographs of a ‘mystery plant’ she found at Felbrigg. This turned out to be the wonderfully named Abraham-Isaac-Jacob, so called because as the plant ages the flowers change colour and you can often find three stages (generations) on the same plant. It was originally from Eastern Europe and was imported to Britain as a garden plant and proved to be a successful escapee, hence its presence in Felbrigg woods. Thank you Sue.
Another imported plant that has done very well in Britain is the Buddleia. There are different types from the Americas, Africa and Asia and one we often see in gardens, which has deep yellow ball-shaped flowers, is Buddleia globosa which is endemic to Argentina and Chile; the most familiar one, Buddleia davidii, comes from central China. This is a large shrub with long purple flowers which is also known as the ‘butterfly bush’ because, like its yellow cousin, the rich nectar attracts many of these insects; it is also loved by moths and bees. However, it is considered to be an invasive plant because its wind-blown seeds will germinate on even the poorest soil. It can be seen growing on any waste ground such as redundant factory sites, on roadsides and along railways and will even root in the crumbling mortar of old brick walls. It is a good plant to have in the garden for the benefit of insects but gardeners are often advised to remove the faded flowers from their ‘butterfly bushes’ before the seeds take off to colonise neighbouring land.
If you wish to take part in ‘The Big Butterfly Count’ this year choose a sunny day sometime between the 15th July and the 7th August. It can be anywhere, in your garden, a park, school grounds or somewhere in the countryside; visit www.bigbutterflycount.org for full instructions.
Sadly, two of our cathedral peregrine chicks have been killed by the intruding female; the other two have been taken into care and will be released when they are fit enough. The Hawk and Owl Trust would not usually intervene in what happens in nature but this was considered an unusual case. Adult peregrines will often fight over territory but attacks on juveniles are not common. Bonding behaviour has been observed between the new female and our original male (fickle bird!) so it looks as though they will be the nesting pair on the spire next year. Let’s hope that the divorced female has also found another mate or will she be drawn back to the cathedral nest. We’ll have to see.
Activities to take part in this month include:
- Bumble bee workshop – Sheringham Park.
- Wildlife digital photography – Holt Hall.
Details email@example.com or Tony Leech 01263 712282.
- Bats of Scarning Meadow – Scarning Water Meadows.
- Insects – Cley Marshes
- How to feed a Dinosaur & The Mammoth Adventure – Cley Marshes.
Contact www.norfolkwildlifetrust.org.uk or 01603 625540.
© Sheila Sims 2016. Email: firstname.lastname@example.org