Wildlife in Buildings
Your Guide to the Conservation of Wildlife in Buildings
Dartmoor's wildlife is a source of pleasure to local people and visitors alike. Those species which are easiest to observe are the mammals, birds and insects that share our homes with us. This is information on how to ensure the continued wellbeing of these creatures, many of which are rare or declining.
This Guide includes the following sections:
- Wildlife in Your Gardens
- Bats
- Swallows, House martins and Swifts
- Barn owls
- Bees and Wasps
- Further Information and Advice
The Wildlife in Buildings Guide is also available in PDF format:
- Wildlife in Buildings PDF
(621Kb) (PDF Help)
Gardens are becoming increasingly important as havens for wildlife, especially in urban areas. Foxes, bats, hedgehogs, birds, butterflies, dragonflies, bees and many other creatures can be seen and enjoyed.
Trees and tall bushy hedges next to bat roosts are important, because they enable the bats to emerge under their protective canopy earlier and benefit from the abundance of midges and other insects most active at dusk.
Choosing plants that are native to Britain benefits all sorts of insects, including bumblebees and butterflies. Flower-rich, lightly mown meadows are much more insect friendly than tightly mown lawns.
Plants without double flowers are better for bees that need pollen to feed to their larvae. This is because in plants with double flowers, pollen bearing anthers have been replaced by extra petals. Remember that bees will pollinate your crops, while wasps will feed on many unwelcome caterpillars!
The trimming of bushes and hedges can be left until winter, after flowers and fruit have been used by insects, birds and small animals.Garden ponds can provide a home or a drinking source for insects, frogs, newts, bird and mammals. And finally, the less pesticides and herbicides are used the better for wildlife!
Of the 16 species of bats in Britain, 14 have been found in Dartmoor National Park and some, such as the greater horseshoe bat, are present in internationally significant numbers. Bats are in serious decline due to the loss of roosting and feeding sites. They are commonly found in houses, especially if situated near to a watercourse or woodland and a large number of roosts have been found in houses in the National Park.
 | During spring, maternity colonies are formed in some houses and single young are born in June and July. As not all females reproduce every year, it is essential to avoid disturbing them in the breeding season. Bats are not confined to maternity roosts, but can use other buildings and houses at different times of the year. They live for up to 25 years and return to the same roosts each year, making them particularly vulnerable to any site losses. |
Most bats enter roosts through small gaps, often only 2.5 cm (1 inch) wide and tuck into crevices in different parts of the roof, such as under barge and soffit boards, in the eaves, between roof tiles and felt, in the roof apex and in cavity walls etc. As a result, bats are often not seen in the loft and instead, their droppings provide the best evidence of occupation. Unlike mouse droppings, which are hard when old, bat droppings crumble into powder – the remains of insects they have fed on. Bats don’t cause damage to buildings as rodents do and they don’t present any health risk.
As bats are very small and elusive, most people live happily alongside them without even realising it!
The legal position
All 16 species of bats in Britain are protected by law and it is an offence to:
- kill, injure, capture or disturb bats
- obstruct access to bat roosts
- damage or destroy bat roosts.
Dartmoor National Park Authority has a legal obligation to take account of protected species when determining planning applications. Generally, any development that involves building or timber treatment work within the roof or loft space could affect bats.
A thatched or slated roof in a rural location holds more potential for bats than a standard building in an urban setting, but as a number of factors determine bat use, it is difficult to predict accurately without a survey being undertaken.
What you should do:
- all planning applications are screened by our Ecologists and if bats are considered likely to be present we will request that a specialist survey be carried out before the application can be determined;
- if you are already aware that you have bats, or that they are likely to be present, we would encourage you arrange a bat survey before submitting your application, as this will help avoid any possible delay to determination.
The bat survey should contain information on how bats use the building, along with a ‘mitigation’ plan, and a description of the methods to be used to minimise any impact on bats. In most cases, this can be achieved by timing the work to avoid the main breeding season and making sure that continued access into a roost is provided after the work has been completed.
As the statutory nature conservation organisation, English Nature may review surveys and provide additional recommendations on how the development should be carried out. The National Park Authority works closely with English Nature, using planning conditions to ensure mitigation where appropriate. Solutions can be found in most situations and a balanced approach is sought to make sure that both bats’ and roost owners’ needs are considered.
If you require more information on bats or need a list of consultants who undertake bat surveys, please contact the National Park Authority Ecology section or English Nature.
Swallows, house martins and swifts
Swallows, house martins and swifts are familiar and much liked birds of rural and urban areas alike. Unfortunately, recent surveys have shown steep declines in all three species, particularly swifts, for which a leaflet Concern for Swifts is available from the RSPB.
Whilst swallows build open nests on beams and ledges inside buildings such as stables, sheds and barns, house martins attach their cup-shaped nests to the outside of buildings under the eaves. Swifts nest just inside the roof, entering through holes under the eaves, between roof tiles or under soffit boards. All three species arrive from their African wintering grounds in April/May. After the breeding season swifts are first to leave in late July and early August, followed by house martins and swallows in September and October.
House martin | Problems with house martin droppings fouling the outside of a building can be easily solved by fixing a horizontal board underneath the nests to catch the droppings. Ideally this should be installed before the birds arrive, about 1/2 metre below the nest, and it can be cleaned off annually after the birds have departed. |
Swallows can be encouraged by providing a flat nesting platform or a ledge inside a building with easy access such as an open window or door. Alternatively, an opening 5 cm x 7 cm (2 ins x 3 ins) wide could be made under the eaves of buildings such as garages or barns. Placing a plastic sheet underneath the nest helps to contain droppings, if these are a problem.
Nest boxes for swifts can be placed under the eaves or in the loft space, with just the entrance hole
visible, by removing a brick or a section of wood. However, these are only likely to work if positioned high above the ground and where swifts are already present in the area. If you would like to prevent other birds from using the nest box, keep the box blocked until your local swifts return in the spring.
The legal position
- All three species benefit from the legal protection given to all birds in Britain under the Wildlife and Countryside Act 1981. This makes it an offence to:
- intentionally kill, injure or take any wild bird to take, damage or destroy the nest of any wild bird while that nest is in use or is being built
- to take or destroy the egg of a wild bird.
Any work affecting birds should therefore be timed outside their nesting season which spans from April to September. Further advice is available from the RSPB or the Dartmoor National Park Authority ecologists.
Barn owls have declined dramatically over the past 50 years, mainly due to diminishing feeding sites and the loss of traditional nesting sites in farm buildings. On Dartmoor, barn owls are still present in a few fringe areas of the National Park, having disappeared from many places in living memory.
Barn owls prefer to nest in roomy, well-sheltered and relatively undisturbed places such as barns, outbuildings, ruins or holes in trees. Their presence in buildings can be identified from long streaks of dried ‘whitewash’ (droppings) down beams and wall ledges, with coughed up black, shiny pellets underneath. These contain the undigested remains of barn owls’ food and could be confused with pellets of other birds of prey, such as kestrels.
When converting a building, it is relatively easy to provide for barn owls. Small ‘owl lofts’ and ‘owl windows’ can be incorporated into the building design, or a nest box can be provided – either inside a building or attached to an external wall, a tree or a tall pole. Where barn owls are occasionally seen but not known to roost, it may be worth providing a new nesting site. However, this is only likely to work where there is sufficient rough grassland nearby to provide a feeding area rich in voles and other small mammals.
The legal position
Barn owls are specially protected under Schedule 1 of the Wildlife and Countryside Act 1981 and it is an offence to intentionally disturb them while they are in, on, or near a nest containing eggs or young; or to disturb their dependent young.
Before embarking on barn conversion or renovation, look out for signs of barn owls. If you are submitting a planning application and you are aware of barn owls or would like to provide for them in a new building, please let the National Park Authority know at the time of application. Appropriate advice can be given by Dartmoor National Park Authority's ecologists or the Barn Owl Trust.
Many once familiar bees and wasps have declined dramatically over past decades, mainly due to the loss of flower rich meadows, pastures and road verges as well as the widespread use of pesticides on farmland and in gardens. The group known as social bumblebees, which have long tongues and feed on deep flowers, are under particular threat.
| Warm south facing walls have certain similarities to cliffs and root plates, the original nesting habitat of solitary bees and wasps. With the exception of a few species, most bees and wasps don’t excavate their burrows but use existing holes in the old burrows of other insects or within the structure of the walls themselves. Some line these nests with imported material such as mud or chewed plants. So before you apply that insecticide to your wall, observe the nest for a period of time to find out whether the bees are actually doing any damage or whether they are using pre-existing cavities. |  |
If control is necessary, insecticides are unlikely to work in the long-term as favoured sites are likely to be re- colonised from the surrounding area. Where serious damage occurs, the best solution is to replace the damaged section of the wall. The old section can be placed in a sunny location nearby as an additional habitat.
Social wasps build their nests in sheltered places under the eaves or in a loft. Most people are wary of them for fear of being stung but unless the nest is in a frequented area, it is best avoided rather than destroyed. Most nests are only used for one year as spring queens generally avoid using old nest sites. Before destroying their nests, remember that social wasps have all been reared on cut up caterpillars and flies!
Social bumblebees, often seen in gardens, build their nests underground or in piles of old vegetation and unless actually picked up, they don’t attack even near a nest.
For further information and advice contact:
Dartmoor National Park Authority,
Parke, Bovey Tracey,
Newton Abbot, Devon
TQ13 9JQ
Tel: (01626) 832093
Office hours 9am – 5pm
Small grants may be available.
Other sources of information
Devon Bat Group (external site, opens new window)
c/o Chris and Helen Shaw
Higher Kingsmoor
Black Torrington
Beaworthy, Devon
EX21 5JN
Tel: (01409) 231364
Devon Wildlife Trust (external site, opens new window)
Shirehampton House,
35-37 St David's Hill
Exeter, Devon
EX4 4DA
Tel: (01392) 279244
English Nature Species Protection Officer,
Trevint House, Strangways Villas
Truro, Cornwall TR1 2PA
Tel: (01872) 262550
www.english-nature.org.uk/ (external site, opens new window)
The Barn Owl Trust (external site, opens new window)
Waterleat, Ashburton
Devon TQ13 7HU
Tel: (01364) 653026
The Royal Society for Protection of Birds (external site, opens new window)
Keble House, Southernhay Gardens
Exeter EX1 1NT
Tel: (01392) 432691
