Environment A to Z of Canal Wildlife
A to Z of Canal Wildlife: J - L

Jumpers - Animal and Vegetable

Frogs are excellent jumpers and can leap over ten times their body length when they have to. They jump to escape their predators, but although they have large eyes on top of their bodies giving them good all round vision, they are quite slow movers, and despite their jumping ability, are an easy target for their numerous predators which include snakes, hedgehogs, herons, rats and pike.There are only three kinds of frogs in Britain, namely, Marsh, Edible and Common, the first two are rare but as its name suggests the third is common, indeed it can be found all over Brifrogtain. The Common Frog is a native, and is the one featured here, the other two are both introductions.The Common Frog, Rana Temporaria, is an amphibian, able to live on land and in fresh water, and can be found almost everywhere in damp grass and undergrowth near still water, ponds, ditches and canals.

The frog has soft, smooth, moist skin and varies greatly in colour. It may be green, grey, yellow, brown, even orange and is speckled or marbled with black, brown or red. It is also capable of slowly changing its base colour to match its surroundings. Thus camouflaged, it sits motionless amongst vegetation waiting for its insect prey.When an insect comes close the frog flicks out its long sticky tongue and catches it. Frogs also eat slugs, snails, (shell and all), and earthworms. It holds the worm in its mouth using its minute teeth and as it swallows it scrapes the mud from the worm's body with its fingers.In mid-October frogs begin their winter hibernation. They crawl into holes in the mud at the bottom of the pond or canal. They have lungs which they use on land, but during hibernation their sole means of respiration is to absorb oxygen through their skin. Immature frogs may hibernate away from water in a damp hole.

In February the frogs emerge from their winter hibernation, and congregate in fresh water preparing to breed. Quite how they find water is a mystery but it is thought they detect the smell of growing algae. During March and April they search for a mate. The 3-inch (7 cm) long male swells his throat and croaks, and the slightly larger female responds with a grunt. He then grabs her, as a partner, with sucker pads on his feet and attaches himself on her back. While the male lies upon her back she swims amongst the weeds and lays her eggs, often 2-3000 of them, and the male fertilises them. The eggs sink to the bottom, but they soon float to the surface as their protective jelly-like coating swells to form the well-known frog spawn. After spawning the adult frogs disperse into the surrounding countryside.

At the end of May, the tadpoles hatch. At first they breath through outer gills, slowly their legs grow, and their tails are lost. Gradually, they develop lungs with which to breathe. During their time as tadpoles many fall prey to other water creatures such as fish, newts, insects and birds, who all take their share, only a small percentage of the original 2000 survive. By mid-July the tadpoles have become transformed into tiny frogs just a half inch (I cm.) long and they then leave the water. It takes them 3 years to grow into mature adults.

Jumping Jack

Jumping Jack, Himalayan Balsam, Impatiens glandulifera, has the spectacular ability of being able to cast its seeds many yards, 10 or more!. This imposing hardy annual in full flower is an arresting sight, the pouched flowers coming in shades from the palest pink to deepest purple.When the seed pods are ripe the slightest breeze on a warm day will cause the pods to explode, scattering the seeds far and wide. On a still day the breeze may be just the passing of a canal towpath walker. Himalayan Balsam, also known as policeman's helmet, stinky pops, bee-bums and poor man's orchid, is the most recently arrived of a family of four to be found in Britain but is easily the most widespread and found along the banks of rivers and canals. It was introduced from the Himalayas into gardens in 1839 and has become widely naturalised. This strong-growing plant has long, large, dark green, lanceolate leaves, thrives in damp places and may well reach 10 feet (3 metres) in height, but is commonly around 5 to 6 feet tall. Its aggressive colonising ability and rampaging spread is due to its explosively fired seeds and the fact that they then float off along the canal to colonise another patch. In some parts of the country its spread is causing real problems, so much so that organised balsam bashes are held to try to control it. Children have learnt to exploit the potential popping of the seed pods. The secret of spectacular explosions is to pick a pod that is dry and just on the point of popping and hold it in the palm of your hand and wait, the warmth soon having the desired effect!.

Kingcups

Kingcup

The Kingcup or Marsh Marigold, Caltha palustris, is a common sight along the banks of canals. Indeed it can be found growing throughout the country in any damp place. It has thick creeping roots and glossy dark green, heart shaped leaves. When it flowers, usually from March to May, but sometimes much later, it is a most conspicuous plant. The large, 1-to 2-inch. (25 to 50 mm) diameter, rich golden, almost burnished buttercup-like flowers rise on 8-to 24-inch (20 to 60 cm.) long stems, and can be seen from afar. The beautiful cup-shaped flower has no petals, but has five large sepals.

The centre of the flower contains a number of carpels which are surrounded by many stamens, after fertilisation these develop into as many follicles containing numerous seeds. After flowering, the leaves continue to grow, sometimes getting disproportionately large for such a small plant. This plant has several natural varieties, differing in flower size and leaf stem colour and type, although all are poisonous they are amongst the most attractive of all canalside plants.

Kingfishers

Although the Kingfisher is surely one of the most conspicuous of British birds, it is surprising to discover just how few people claim to have seen one. They are common and widespread anywhere there is clean fresh water. Slow flowing rivers, and streams are favourite haunts, but large ponds, gravel pits and canals also provide hunting grounds in which to catch their prey, mainly fish. Although the kingfisher, Alcedo atthis, resplendent in its colourful plumage, an iridescent greenish blue above, with under parts of rich deep orange, should be easy to spot, it is nevertheless quite a shy bird and an extremely fast flier. Even anglers, sat for hours beside their bobbing floats, faKingfisheril to catch a glimpse of them as they flash past in a fraction of a second. However, if you know where to look and what to listen for they can easily be seen. The secret is to listen carefully.

The kingfisher is prone to giving an audible warning on its approach, a shrill short ‘chee’, announcing its arrow straight flight just feet above the water. So look low and marvel at just how fast it is flying without seeming to flap its wings. As the bird has short stubby wings it has to flap them so vigorously that they become almost invisible. The short strong wings allow the bird to dive for its food, normally small fish, sticklebacks, minnows and fry of larger fish, but tadpoles and insects are also taken. The bird sits patiently on a favoured branch overhanging the water,---- waiting. Suddenly it dives into the water to grab a passing fish with its huge dagger-like bill. On returning to the perch, the bird kills or stuns the fish by banging its head on the branch before juggling it in its beak and swallowing it head first. If a waterside perch is not available, then the bird will hover above the water in search of fish.Kingfishers nest between April and August, they excavate a 2-to 3-feet (60-90 cm) long burrow in steep sandy or clayey banks of a slow-moving stream or river.

Because they are man made, canal banks are generally unsuitable as nesting sites so they rarely nest there but just use the waterway in their wide-ranging hunt for food. The two birds need several days to excavate the gently rising burrow and, if the ground is hard, may take several weeks. They dig with their beaks and scrape out the excavated soil with their short legs. The female lays between 5 to 7, glossy white eggs approx. 0.75inches (20mm) long, in a nest chamber at the end of the burrow. Both parent birds incubate the eggs, which take 18 to 21 days to hatch so the young are usually different sizes. They are fed on a diet of fish and leave the burrow after 3 to 4 weeks. Kingfishers raise two or three broods each year. In times of plenty, the female may well start to sit on another brood in a nearby burrow, before the last one has flown. Hard winters, when the water is frozen for long periods, take a heavy toll of these birds, but remember, Kingfishers are still common, so listen and look low and, we promise, you will see this most beautiful bird as it flashes past on its journey from one favoured perch to another

Larvae and Lilies

Both of our common, and well known, water lilies can be found growing along canals in the shallower still water of the undisturbed margins.

They are easily identified when in flower. Nymphaea alba has white flowers in July and August and has larger leaves than Nuphar lutea which has yellow flowers from June to August. They both have large underground stems or rhizomes which anchor them in the mud at the bottom. Their heart-shaped leaves and their flowers grow up from the bottom, the stems are spongy and full of air spaces which give them buoyancy so they float at or near the surface.

Although the leaves are large, and can be numerous, blanketing a large area, they do not shut out enough light to harm other aquatic life. The white water lily has the larger and more attractive flowers and at night the petals collapse and the flower may sink below the surface to re-emerge the next day. The smaller flowered yellow water lily is sometimes known as brandy-bottle because it is said to smell like stale brandy and also the seed head, which forms above water after the petals fall, is flagon shaped.

The half-light below the leaves of the water lily is a favoured summer haunt for much aquatic life including some of the nymphs and Larvae of some common insects. Larva, is the term applied to the stage in an insect's life from emergence from the eggs to when it transforms into a pupa. (The caterpillar of the Cabbage White butterfly is probably the most familiar larva). Different larvae can be found at all levels of the canal, under stones, in the mud, amongst vegetation, in the shallows and at depth, and in stagnant and clear water. There are far, far too many to mention in detail here but commonly found in canals are the larvae of the diving beetle Dytiscus species, the caddis-fly Phryganea species and the common gnat Culex pipens. They all form an important link in the food chain, eating other wildlife and, indeed, being tasty morsels themselves.