THE SONG THRUSH

THE SONG THRUSH

The number of song thrushes has plummeted in the past 30 years. Some reasons for the decline include loss of hedgerows, increased use of chemicals in the countryside and intensive farming methods.

This article contains three sections. The first contains facts about the life and times of the song thrush, the second discusses song thrushes in the garden and ways to attract them and the third suggest sources of further reading.

1 Facts about the song thrush

Telling the difference between the song thrush and the mistle thrush

The song thrush is a warmer brown colour than the larger mistle thrush and has a distinctive song, as it tends to repeat each note or phrase several times.

Distribution

Song thrushes are distributed across most of Europe. The UK population is mostly resident, although some birds do move southwards into France and Spain in the winter, although this seems to be weather related. The northern European population migrates in the autumn and again in the spring and some over winter in the UK.

Song Thrush

Habitat

Song thrushes exist almost anywhere with trees or bushes and open grassland. They need soft ground that will support invertebrate food, especially earthworms and snails. They have adapted well to environment created by people and make use of small woodland, parkland, railway embankments, roadsides, cemeteries, gardens and even cities. Song thrushes are normally shy birds in woodlands; however, in towns some can become quite tame.

Food

Song thrushes eat a wide variety of invertebrate and plant food. The earthworm is a key food, whenever available. When the ground becomes hard, such as in late summer, then snails become particularly important. The birds beat the snail against a hard surface, such as a stone, until the shell breaks. The snail is then wiped across the ground to remove the slime. Slugs are also eaten. Other food includes caterpillars, and fruit and berries, when available.

Territory and social behaviour

Song thrushes tend to be solitary birds. Small winter groupings occur at good sites, and those individuals that migrate do form large but only loosely co-ordinated flocks.

They establish a breeding territory in the late winter or early spring, for pairing and nesting but only a part of the food for the young is obtained from within it. Territory sizes vary from 0.6 - 6 hectares. (Think of 1 hectare being 100m by 100m) These territories break down in late summer although many males remain in the previous years territories. Winter territories will be abandoned during periods of severe weather.

Nesting

Song thrushes have 2-3 broods from March through to August. The nest, built by the female, is located low down in any suitable cover, including in trees and shrubs, amongst creepers on walls, on ledges, and on the ground amongst thick vegetation. A neat structure of twigs, grass, moss and cemented together and lined with mud, dung, leaves and rotten wood. It can take up to 3 weeks to complete and can be used for successive broods.

The normal clutch size is 3-5, with one egg laid each day. Incubation only starts when the final egg is laid, and the chicks hatch 13-14 days later. Although only the female broods the chicks, both parents feed them. This is primarily on worms, but slugs, caterpillars and fruit can feature in the diet, especially during dry weather.

Fledging

The chicks are ready to leave the nest after 13-14 days, but can leave earlier if the nest is disturbed. For the next few days they are flightless and remain in cover but as soon as they can fly will follow their parents for food. They continue to be fed by their parents whilst they are learning to feed for themselves. They will be independent around 3 weeks after leaving the nest.

The male often looks after the fledged young whilst the female is preparing the nest for the next brood. There are considerable losses at egg and chick stage, with only a third of nests producing fledged young.

Orphaned birds

Now and again partly developed birds are found outside of the nest. If possible, the chicks should be returned to the nest. Otherwise, the chick’s survival is dependant upon human care. Note – intervene only if the chick is not fully feathered. Hand rearing is time consuming, with a low success rate, and should be attempted as a last resort. In most instances, the orphaned young should be passed on to an expert rehabilitator. Fledged birds are almost certainly not orphans and should be left alone, unless they are in a place of danger. Under these circumstances, moving them a few feet out of harms way makes good sense.

Moult

Adults undergo a complete moult during the summer. All feathers are replaced, a few at a time over a period of a few weeks. The young birds moult their body feathers in the late summer at which point they obtain almost full adult plumage. The wing and tail feathers are kept until the following autumn.

Threats, dangers and survival

Song thrushes are relatively short-lived birds, living on average 3-4 years; although the oldest recorded individual lived to reach 13 years 9 months! Mortality is high and the reasons many and varied. Only 20% of fledglings and 60% of adults survive to breed the following spring.

There are serious concerns over the song thrush population in the UK with anecdotal reports of declines since 1950. The long term population monitoring carried out by the British Trust for Ornithology (BTO) shows a major decline since the mid 1970’s. This has been most pronounced in farmland where a decrease of 66% has been recorded. It appears to be due to the intensive farming methods in practice today. This has led to a loss of hedgerows and wet ditches, removing feeding and nesting sites, whilst increased land drainage, tillage and pesticide usage are all likely to have reduced the numbers of earthworms and invertebrate prey available to song thrushes. In such farming areas, most song thrushes breed in or close to gardens and few fledglings survive their first few weeks after leaving the nest.

It has been suggested that increases in the number of magpies and sparrow hawks may also contribute to the decline. Studies have proven this untrue. The proportion of thrush nests, which are predated, has declined during the past 30 years and studies of 250 farms have shown that the decline of song thrushes is not in proportion to the changes in magpies and hawk populations.

Song Thrush singing its distinctive song.

It tends to repeat each note or phrase several times.

The song thrush and the law

Song thrushes and their nests are fully protected by the law. It is illegal to kill, injure or take any wild bird; or intentionally take, damage or destroy their eggs, young or nest of a song thrush. Therefore, it is essential to ensure nests are not destroyed if hedge trimming or tree felling is carried out in the breeding season.

2. Song Thrushes in gardens

What do song thrushes need to survive?

The bulk of their diet is made up of earthworms and snails, particularly when other sources, such as insect larvae and berry crops are not available. Therefore, damp ground is required.

They require safe nesting places in woodland, with thick under storey of shrubs or brambles; or sites with tall thick hedgerows and dense garden shrubs. They start nesting early so any hedge trimming or pruning should be completed by February.

Hedgerow fruit, which usually will grow on, second year growth

How can I encourage song thrushes?

Look after hedgerows and shrubs

Try to keep thick vegetation near to tall trees. Do not prune during the breeding season from March to August. Try to grow berry bearing shrubs and trees such as barberry, cotoneaster, cherry, crab apple, elder, firethorn, hawthorn, holly, rowan and spindle. Trim hedges and berry bearing shrubs on once every 2 to 3 years and if possible avoiding trimming all hedges in the same year.

Manage lawns and other grassy areas

Grassy areas are excellent feeding places for song thrushes, blackbirds, robins and starlings. Choose a vigorous seed mix that requires little attention, welcome some weeds – clover releases nitrogen and yarrow keeps the lawn green in summer. Do not cut the lawn below 2.5cm or 1 inch to reduce water loss. Leave the grass mowing on the lawn to feed it. Only remove it in the early spring and autumn when it will take too long to decay. Allow some areas to grow longer and to flower to attract insects and flowers.

Controlling pests

Use of pesticides to kill slugs and snails reduces the food supplies for song thrushes and can contain dangerous chemicals that are harmful to wildlife and pets. Other non chemical methods to harmlessly attract slugs are using a steep sided container sunk into the ground and filled with a sweet liquid such as beer or using a hollowed out half orange placed face down.

The ideal home!

Damp ground and edges of ponds are mini- wetland habitats that will be rich in insects and other wildlife. Undisturbed piles of leaves left to rot will contain many earthworms, slugs and snails. Untreated wood or logs, in a shady spot, will attract woodlice and some beetles. Finally, build a compost heap to recycle the nutrients in the garden and to provide a frost-free area where birds can find insects and weeds.

Risks and opportunities

People have control over:

• Paving i.e. no grass
• Predators i.e. Cats

3. FURTHER READING

The Song Thrush by Eric Simms. Shire 1988

British Thrushes by Eric Simms. Collins 1978

Also a number of helpful leaflets are available from the RSPB.

These include:

Help us save the song thrush – parks and gardens Farming for birds – song thrush RSPB information – song thrush RSPB information – Cats and garden birds Make birds and the environment count – joining information RSPB free guide to birds in your garden For further information or copies of the free RSPB leaflets lease contact the RSPB South East Regional office:

RSPB South East Regional office 2nd Floor 42 Frederick Place Brighton East Sussex BN1 4EA

Phone number: 01273 775333

4. LINKS TO FURTHER INFORMATION ON THRUSHES

Song Thrush

song thrush

Mistle Thrush

Mistle thrush

RSPB Training events

For a leaflet giving details of RSPB training days for a variety of habitats in 2008 click here: rspb training 2008.pdf

Click here to go to the RSPBs website