Programme Five: Stones

The fundamental philosophy of wildlife gardening is that it provides a shared resource, where the owner can grow food and create an attractive and satisfying garden where native plants and animals can also thrive. Many animals that do take up  residence often help to keep garden pests under control and their daily activities provide a year-round source of interest for the garden's owners.

Most gardeners like to enclose their personal patch of paradise with walls or fences and also create paved areas where they can sit and enjoy the fruits of their labour on sunny days. Even these patches of hard landscape soon acquire a native animal fauna all of their own. Butterflies and spiders like to sunbathe on sun-drenched stones, ants will build their nests under paving, while lichen-covered rocks with their mossy crevices add character to a garden and provide a home to vast numbers of minute animals, beyond the range of the human eye, at the bottom of the food chain. 

What could be more satisfying, on a sunny summer afternoon, than sitting in a deck  chair, listening to thrushes crack open snails on the garden path or hearing them deliver their exultant song from the rooftops? That's the feel-good reward for the wildlife gardener.

Wolf spiders

Male wolf spiders conduct their perilous courtship on sun-warmed stone surfaces. The smaller males have two black palps on their head which they use like semaphore flags, waving them at the larger and very aggressive females to indicate their amorous intentions. When she's pacified, which often entails long periods of intense palp-waving, cautious approaches and sudden retreats, they mate and in due course ....

........ the female reappears with her egg sac attached to her abdomen. She spends the long summer days sunbathing on rocks or garden paths until ....

.......... her brood hatches, and then she carries her spiderlings around on her abdomen until they are large enough to fend for themselves.

Wolf spiders don't build webs. Instead they stalk and chase their prey, impaling it with their fearsome jaws.

Zebra spider

Black-and-white striped Zebra spiders are tiny but have a deadly hunting technique. They like to sunbathe on warm surfaces, like house walls and window ledges, waiting until small flies land within range. Then they leap on their prey, but not before securing their themselves to their perch with a silken safety thread.

The secret of a zebra spider's hunting success lies in its eyes. Two of these are enormous in relation to the size of the spider and they give it excellent vision and the ability to judge distances accurately. 

Slow-worm

Slow-worms, which are legless lizards, are the reptiles that are most likely to turn up in a wildlife garden. They like to shelter under sun-warmed surfaces, so sometimes occupy spaces under rockery stones, emerging to hunt small soil animals and slugs.

If you have slow-worms in the garden, take great care if you pick them up - which is very tempting, because the feeling of a slow-worm sliding between your fingers is a delightful sensation. Never pick one up by the tail because their defence when they're gripped in this way is to shed their tail, which continues to wriggle while its owner slithers away to safety. It will regrow its tail but the new one will be short and stumpy, spoiling the beautifully tapered body shape of the intact animal.

Song thrush

The song of a song thrush, often delivered from a tree top or house roof, is a glorious sound at the end of a long summer day. But these are more than just songsters - they are incredibly efficient hunters of garden snails and the evidence of their activity is there to see on rocks or on the garden path, in the form of broken snail shells. 

Song thrushes grip snail shells by their lip and whack them against an anvil stone - listen and you'll sometimes hear the fatal blow, when the shell cracks and the mollusc's fate is sealed.

Song thrushes will readily nest in gardens and by early summer their fledglings leave the nest. Within a month they too will be terrorising the garden snail population

Ivy

You can enhance the wildlife value of a garden wall by clothing it in ivy. This is one of the most useful native plants for wildlife in the garden because its whole life cycle is out of step with most other plants.

In spring it produces its black fruits, just when migratory birds need them most, while it  autumn it produces its flowers, rich in pollen and nectar, but when all the other flowers are dying ...

.

Many butterflies and other insects use ivy flowers as their 'last chance saloon', topping up their energy supplies with nectar before winter arrives.

Ivy's evergreen leaves produce a secure, waterproof hibernation site for a host of insects, like brimstone butterflies for example, and in spring they provide cover for early nesters like blackbirds.

Holly Blue Butterfly

Holly blue butterflies, with their exquisite silky undersides and vibrant blue wings, readily breed in gardens, even in the suburbs of large cities. To host a colony you need two plants in the garden - holly and ivy. Holly blues produce two generations each year. The spring generation lays its eggs on holly flower buds in early May and the late summer generation lays eggs on ivy flower buds.

Ants

Ants like to excavate their nests under sun-warmed stones - often under garden path flagstones. Although small, they are immensely strong and will drag back prey -  like this spider that's several times the weight of the ant - to their nest.

When ants' nests are disturbed their first instinct is to 'save the children', grabbing their white larvae and pupae in their jaws and carrying them away to safety. 

If you have a black ant colony in your garden you might sometimes find them clustered around greenfly on plants. These ants satisfy their craving for sugar by 'farming' aphids - stroking them with their antennae to persuade their 'herd' to provide honeydew, in exchange for protection.


The most spectacular event in the black ant's calendar is the nuptial flight when, on warm, humid days in summer, swarms of winged males take flight in pursuit of winged queens. The column of ants rises like smoke, then the mated queen returns to earth to shed her wings and start a new nest, leaving the males to the mercy of twittering flocks of swifts and swallows that arrive from far and wide to feast on them

Programme four: Trees and Shrubs

The widest range of species is often found where two habitats meet - where woodland grades into grassland for example, where tall trees give way to shrubs and then wild flower meadow. 

The varied heights of trees and shrubs, with its variety of feeding opportunities, make this a varied and particularly attractive habitat for many birds, like tits and warblers, and for butterflies like the speckled wood, which will breed in gardens.

It's easy to recreate something similar, with its constantly shifting mosaic of dappled sunlight and shade, simply by creating storied layers of vegetation in the garden.

Many birds like to nest in mature trees but even young trees are good places to mount nest boxes. If you plant native tree and shrub species that have a rich and diverse insect fauna, like birch, mountain ash (rowan) or hazel, blue tits and robins will visit them to collect caterpillars for nestlings. 

Blossom trees like cherries, plums, pears and apples provide nectar and pollen for bees in spring and rotting fruit for autumn bird visitors and even for butterflies - peacock and red admiral butterflies love to drink the juice of over-ripe plums.In mature gardens old trees and even tree stumps are also a very valuable wildlife resource in their own right, sometimes attracting more exotic birds like great spotted woodpeckers and treecreepers that search for insects on dead branches and bark crevices

Looper caterpillars

Looper caterpillars move forward by drawing their tail end forward, so that they throw their body into a loop, then gripping with their tail and stretching out their head-end. They are the larvae of moths known as geometrids, so-called because they seem to be measuring their movements with geometrical precision (which also accounts for their other name: inchworms.

Most trees and shrubs will have larvae of one of the many species of geometrids feeding on their foliage. They are a major component in the diet of blue tits and great tits during the breeding season; a pair of great tits need to find up to 700  per day to feed their brood by the time they are about to fledge.

Many geometrid larvae are amazingly well camouflaged, resembling dead twigs or matching the colour of leaves. When danger threatens they often 'freeze', remaining perfectly still and relying on their cryptic colouration to escape detection.

Spot the caterpillar (above): almost a perfect match!

Not all geometrids rely on camouflage. The larva of the magpie moth is brightly coloured. Birds that try to eat it find it distasteful and the warning colouration acts as reminder that they shouldn't make the same mistake twice.

White-lipped Snails

These striped snails will often climb into bushes either to graze on the algae that grows on the stems or to spend the driest months of the year in a state of dormancy called aestivation. Then they seal their shell opening with a layer of dried mucus and glue themselves to the stems.

White-lipped snails come in a variety of different shell colour banding patterns. Some, found most often on sand dunes, have no shell bands at all. The frequency of the different types varies from place to place and is thought be be related to camouflage (they are favourite food of thrushes), although exposure to sunshine may play a part to - snails with broad dark bands tend to heat up faster, plain pale shells are less likely to overheat.

Plant Galls

Bedeguar gall (aka moss gall) on wild roses

Wild roses in hedgerows often carry these mossy crimson growths, known as bedeguar or Robin's pincushion galls. They are caused by a tiny wasp that lays its eggs in leaf buds, inducing them to produce a mass of tissue where its grubs can grow and feed on special nutritive tissue that the plant produces.

This is the minute wasp that causes the growth, Diplolepis rosae. A large bedeguar gall will contain over thirty developing larvae but many never reach maturity because....

..... they are parasitised by this minute but deadly ichneumon wasp.

As the poet Jonathan Swift quipped:

"So nat'ralists observe, a flea

Hath smaller fleas that on him prey;

And these have smaller fleas to bite 'em

And so proceeds Ad infinitum."

More Galls

The strange growths on plants known as galls are induced by a variety of different organisms including fungi, flies and microscopic mites but the most elaborate are caused by gall wasps. The pink flying saucer-shaped galls and those that look like golden embroidered silk buttons on the oak leaf below are caused by two closely related species of gall wasp. The pink spherical gall is caused by a third species.

Some galls can be very destructive. This is the knopper gall, caused by a gall wasp that lays its eggs in very young acorns and causes them to develop into a gall that looks like green popcorn. Knopper gall wasps spend half of their life cycle on native oak trees and half on the introduced Turkey oak, which is cultivated in parks, botanic gardens and arboreta, so you tend to find knopper galls most frequently where the native and introduced oaks grow in close proximity.

This is the marble gall, accidentally introduced in the early 19th. century when the called, which are rich in tannin, were imported for the leather tanning industry. Here the wasp lays its eggs in a leaf bud, which develops into a woody sphere with the developing wasp inside. The exit hole, where the wasp has hatched, is clearly visible here. Blue tits learn to peck into these galls to eat the grubs in winter, when other food is hard to come by.

Several trees, such as sycamore, maple and alder (above) carry large numbers of small red pimple-like growths on their leaf surface in late summer.

These are pocket-like ingrowths caused by minute mites that feed and breed inside. Here you can see them emerging from the mouth of the pocket on the underside of the leaf, and .....

.... here you can see them highly magnified, under a microscope.

Native Trees for a Wildlife Garden

Native trees are a rich resource for insects, which use them as a food source, and for birds that feed on the insects. Large forest trees, like ash, oak or lime grow too large for all but the grandest gardens by there are several smaller natives that fit comfortably into a plot of any size and can even be grown in large containers.

Silver Birch

Attractive white bark, small leaves that turn lemon yellow in autumn and a graceful pendulous habit all year round make this a particular attractive species. It supports more species of insect than any other native tree apart from oak, so is a favourite feeding site for hungry blue tits and great tits in spring and summer. Over 80 species of moth caterpillar alone feed on its foliage. 

In spring the tree produces these long, slender catkins from the tips of its twigs and..... 

.................in autumn silver birch trees carry catkins of small seeds that are a good source of food for ....

..... siskins ......

...... and redpolls. Once the supply of birch seeds runs out they'll turn their attention to your bird table if you supply niger seed.

Rowan, also known as Mountain Ash

Rowan, also known as mountain ash, is an excellent native tree for wildlife gardens because it does not grow very large or cast too much shade and it also flowers when just a few years old. It's an all year-round wildlife resource.

Rowan blossom, which has a distinctive scent, appears in early summer and provides a rich nectar and pollen source for many insects, including wild bees.

Many hoverflies, like this Leucozona lucorum, live on a diet of pollen, so the dense masses of rowan flowers is a valuable resource for them.  

Rowan produce heavy crops of berries which ripen in early autumn. Blackbirds are particularly fond of them. 

The Value of Old Trees

As trees mature their smooth bark develops deep fissures that are home to spiders and a host of small insects that attract the attention of hungry nuthatches and tree creepers in winter.

Garden trees continue to be a wildlife habitat even after they are dead, so leave old tree stumps in the ground where they can slowly decay. Allowing ivy to grow over them can also enhance their wildlife value.

Many beetles lay their eggs in dead branches and tree stumps and the larvae slowly tunnel their way through the decaying wood. Its nutritional value is low but these specialist feeders are adapted to slow development, often feeding for two or three years before they pupate and then hatch as adults. This plump beetle larva would be a fine meal for a great spotted woodpecker.

Great spotted woodpeckers often visit bird tables in winter - and while they are in the garden they'll sometimes take the opportunity to explore old tree stumps for beetle larvae.

Perhaps the ultimate reward for a gardener who leaves old tree stumps to rot in the garden is discovering that the endangered stag beetle has chosen to lay its eggs in it. The larvae of these spectacular beetles take four years to develop, feeding on the rotting wood. The People' Trust for Endangered Species has useful advice for gardeners who want to help conserve stag beetles - scroll down to the bottom of the page to find links to their web site.