Nothing in wildlife gardening provides faster or more satisfying payback than installing a garden pond, however small. Even a half-barrel of rainwater, planted with a few water plants, will attract animals like water beetles and even damselflies, as well as providing a place where birds can come to drink. Ponds are the most biodiverse of all garden wildlife habitats and frogs and dragonflies will often take up residence within a year.
Numerous insects breed in water and their larval stages provide food for a wide variety of aquatic animals, while their adult stages attract bats at dusk. The boggy edges of ponds provide opportunities to grow some of our most attractive native pond-side plants, such as lady's smock (food plant for orange tip butterfly caterpillars), purple loosestrife, marsh marigold and yellow flag iris. Ponds are the theatres of the garden, where you can watch the noisy courtship of frogs in spring or the underwater ballet performed by newts, listen to the sound of a blackbird splashing as it washes its feathers on a hot summer afternoon or enjoy the magical transformation of a dragonfly emerging from its nymphal case. There's always something going on in or around ponds, all through the year.
If you have children ponds can be dangerous but a bog garden, where the drainage is impeded with a liner under the soil, can be an excellent substitute, creating a habitat for a range of wetland wild flowers that will support a wide range of bees, butterflies and other insects.
Surface dwellers
The surface of the pond is the site of constant activity. Some tiny animals are adapted to walking and feeding on its elastic surface film, whilst others that live in the pond must regularly rise to the surface to breath.
Pond skaters and Whirligigs
Pond skaters are predators that hunt on the pond surface. They detect ripples from unfortunate struggling prey that has become trapped in the surface film and ......
.......scoot across the pond surface with amazing speed, using their middle pair of legs as oars and their hind pair as rudders.
Their front pair of legs clasp their prey. The tips of the legs are covered in tiny waterproof hairs that prevent them from breaking through the surface film.
When they detect the ripples from a struggling victim - in this case a wasp that came to drink in the pond but became trapped - the pond skaters descend on it like a pack of wolves.
Whirligig beetles
These are the tiny black beetles that gyrate in the surface film of a pond, like living funfair bumper cars that never collide. Like pond skaters they navigate by sensing the ripples on the surface, in this case created by fellow whirligigs.
Whirligig beetles have two pairs of eyes - one pair that looks down into the water and another that looks upwards, so they can look skywards and see what's going on underwater at the same time.
You an watch a movie of whirligig beetles gyrating by clicking here. This video comes from the excellent ARKive wildlife web site.
Under the surface film
Backswimmers and Water boatmen
Backswimmers (above) and waterboatmen (top) both hunt on the bottom of the pond but must rise to the surface frequently to collect air at their tail end. Their natural buoyancy means that they readily float to the surface, so they use their long, powerful swimming legs to dive down into the depths of the pond again.
An easy way to distinguish these two species is to look at the way that they swim: backswimmers swim on their backs, underside uppermost; waterboatmen swim back uppermost.
It's unwise to catch and hold a backswimmer in you bare hand - their powerful mouthparts can prick skin!
Down in the depths
Frogs and tadpoles
The purring courtship calls of frogs announce the arrival of spring. Males emerge from hibernation and return to the pond first, holding vocal contests and splashing each other with water when they compete for the returning females.
Even small garden ponds can soon build up a large frog population. They're useful animals to have around because they'll eat slugs and many other garden pests.
A single female frog can lay around 1000 eggs but only a small proportion survive to become adults because there are many other pond animals, including water beetles and dragonfly larvae, that will eat tadpoles.
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Frogs are wary when they first return to the pond but soon become accustomed to the presence of gardeners. As the summer progresses they can even be tamed; if you hold out a small slug on the tip of your finger frogs will sometimes flick their tongue out and take it!
For many people, watching frog spawn hatch into tadpoles and then metamorphose into froglets is one of the abiding memories of childhood. These transparent eggs offer an opportunity to watch one of nature's most amazing processes - the division of a single fertilised cell, growing into a complex embryo and then into a living independent animal.
Only amphibian eggs offer the opportunity to watch this transformation with the naked eye - in birds and reptiles the development of the fertilised egg is hidden by the egg shell and in mammals it all takes place hidden inside the mother's body. Look closely at a newly laid mass of frog spawn and you'll see....
..... a cleft develop in the fertilised egg nucleus (the red object, right foreground above); this is the first stage in the inexorable process that will produce millions of cells that are genetically programmed to organise themselves into a frog.
Dragonflies
For tadpoles, danger lurks on the bottom of the pond in the shape of the formidable larvae of dragonflies.
Adult dragonflies, like this common darter, are incredible agile aerial hunters that, aided by their enormous eyes with almost 360 degree vision, can catch other small insects flying above the pond surface.
Southern hawker dragonflies wander considerable distances from the pond where they hatched and will quickly colonise small suburban garden ponds, laying eggs in wet moss around the pond margin, near the waterline.
The eggs hatch into larvae called nymphs that take two or more years to reach maturity.
Dragonfly nymphs prowl amongst the pond weeds, catching tadpoles with the aid of long, hinged jaws that can extend with lightening speed and impale their prey on needle-shape fangs.
One of the most memorable experiences for a garden pond owner is to watch the emergence of an adult dragonfly from its nymphal case, called an exuvium. The nymph crawls up a pond edge plant stem, usually early in the morning, and then splits along its back, allowing the adult dragonfly to emerge. It can take a couple of hours for the dragonflys wings to extend fully, before it begins hunting above the water surface. The empty exuviae often remain attached to the plant stems.
You can watch a movie of a dragonfly hatching by clicking here. This video comes from the excellent ARKive wildlife web site.
You can watch a movie of a dragonfly hatching by clicking here. This video comes from the excellent ARKive wildlife web site.
Some more pond residents
Scores of different animals live on and around ponds, including many small insects like gnats and mosquitoes that swarm above ponds at dusk and are important food for bats like pipistrelles, that hunt over gardens in summer.
Mosquito larvae like these rise to the surface so that their tail ends can penetrate the surface film and collect air through a breathing tube. They swim with a powerful wriggle, needed to break away again from the surface tension and dive back into the deeper water. These insects are important links in a food chain that feeds predators like dragonflies and bats.
Newts
One of the joys of owning a garden wildlife pond is to sit on the margins on sunny summer evening and watch the mini-dramas that take place below the surface - and none is more captivating than the balletic courtship dance of newts.
Here a male palmate newt pursues a female through a swarm of pink water fleas.
Male newts develop attractive colour patterns during the courtship season and ....
Unlike frogs, female newts lay their eggs one at a time and carefully wrap each one in a water weed leaf.
You can watch a movie of a newt courtship dance by clicking here. This video comes from the excellent ARKive wildlife web site.
