Habitats for Farmland Birds under REPS
Catherine Keena, Countryside Management Specialist, Teagasc
Catherine Casey and Alex Copland, BirdWatch Ireland
Wildlife habitats are important because of the flora and fauna that live in them. Flora includes flowering plants, ferns, conifers, bryophytes (mosses and liverworts), fungi, lichen and algae. Fauna includes mammals, birds, reptiles, amphibians, fish and invertebrates (worms, insects and crustaceans).
Of all flora and fauna, birds are probably the most popular. They are also good indicators of the state of the environment. Several countries have adopted national bird monitoring schemes (Hustings, 1992) and use breeding bird populations as indicators of sustainability (Gregory et al., 2001; Peakall, 2000; Van Strien et al., 2001). Birds are easy to identify, their classification and ecology are generally well established. They are high in the food chain and thus may be particularly suitable as monitors of any signal that accumulates throughout the chain (Jarvis, 1993).
Traditional farming was friendly to farmland birds. Intensification and specialisation resulted in the loss of some wildlife habitats and their associated species. In recent years, awareness of environmental issues has increased. Agri-environmental schemes promote measures to protect and enhance habitats on farms. Sometimes, small adjustments to farming practices can benefit birds. Other wildlife usually benefits too. Awareness is the key issue.
Farmland birds are associated with different habitats; hedgerows; field margins; peatlands; wet grasslands; arable and intensive grasslands; farmyards and forestry. Examples of birds in each habitat are described. Protection measures and suggestions for enhancement are discussed.
The song thrush is smaller than its close relative the mistle thrush. Upperparts are brown, and underparts are creamy white with black spots. Although evidence from Ireland is patchy, in Britain song thrushes have declined by more than 70 per cent on farmland in the last 25 years.
Song thrushes are found where there are trees and bushes near to grassland, leaf litter or moist ground. They nest in trees, shrubs and hedges. Adults feed on a wide range of invertebrates and fruit, while chicks are fed primarily on insect larvae.
Protection and Management
All hedgerows must be retained in REPS. A five year management plan for boundaries is prepared. The scheme has created awareness, discussion and some confusion about hedgerow management. Confusion has arisen because the purpose of hedgerow management is not clearly understood. Also Irish hedgerows come in various forms, each which requires totally different management.
Variety and diversity in hedgerows are essential for wildlife. A variety of species gives continuity of food supply. A large hedgerow, in both height and width provides more food and concealment. Hedgerows, thick at the base including trees and tall shrubs are used as nest sites, song posts, feeding sites, cover from predators, roosting sites and corridors for movement. Dead wood and rotting timber full of fungi and insects, provide food and nest holes.
A hedgerow is a line of shrubs and trees. They are designed by nature to grow to maturity at heights of 3 metres for blackthorn and spindle; 6 metres for whitethorn and hazel; 15 metres for holly and rowan; and 30 metres for ash and beech. Left alone, shrubs become mature trees, grow old and die.
Types of Irish Hedgerows
1. Hedgerow thick at the base
This hedgerow has not grown up into trees because it has been trimmed. It requires regular trimming to maintain it. While light annual trimming can benefit the hedgerow, it is not good for wildlife, as flowers or fruit are not produced. The best compromise is usually to trim every five years. It is recommended to trim to a triangular shape, leaving the peak as high as possible. Allow mature trees and saplings to grow at irregular intervals. Many hedgerows in this category in Ireland need to be allowed to grow taller.
Clean cuts are essential for good re-growth. If a flail is used on stems over approximately two centimetres or if there is a poor edge on the flail, the result is shattered and frayed branches. This leads to disease and decay of the branches and ultimately a useless hedgerow.
- Do not cut hedgerows from late February to the end of August to avoid destroying nesting birds. Late winter is best, if practical. It avoids destroying the supply of fruit, seeds and berries in autumn.
- Cut hedgerows on a five year rotation around the farm.
- Cut the sides of the hedgerow, gently sloping from a wide base.
- Sharpen equipment as necessary - at least once per week if working full time.
- Leave saplings to grow into hedgerow trees every 20 to 30 metres, located irregularly for a natural look.
2. Relict hedgerow
This hedgerow has become a line of mature trees and shrubs. They are stemmy and top-heavy. While it has lost the advantage of the thick base, it is still extremely valuable to wildlife. It is also visually very attractive in the landscape. Relict hedgerows should not be cut. The disadvantage is that the trees will die eventually. Fencing off stock from both sides prevents deterioration by stock tramping through the gaps. A valuable strip of natural vegetation develops. On farms with a lot of relict hedgerows, consider planting new hedgerows elsewhere as replacements for the future.
3. Escaped hedgerow
This has grown into tall stemmy shrubs, but not yet into mature top-heavy trees. Cutting a stemmy hedgerow at around one metre is not advisable, as it will produce bushy growth at this height, leaving a gappy base. Escaped hedgerows can be rejuvenated by laying or coppicing.
- Cut stems near ground level almost but not quite through to the bark, laying them over and securing them. This results in an instant stock-proof barrier. New growth comes from the cut stumps. This eventually takes from the laid stems, which also keep growing for many years.
- Cut all growth close to ground level. New growth comes from the cut stumps. Protect re-growth from stock by fencing. Re-plant gaps.
When laying or coppicing, hedgerows must be in good condition and not diseased. Beech will not coppice. Coppicing should be done in late winter or very early spring before buds break.
In the short term, laying, and particularly coppicing, dramatically alter the visual appearance, wildlife and shelter value of the hedgerow. All benefit in the long term. For these reasons and from a practical work point of view, such work should only be carried out in small lengths and in rotation around the farm.
It will take time to improve our hedgerows. In the meantime, harm must not be done by inappropriate management.
Understanding the factors that govern the distribution of animals between habitats is important for conservation (Bernstein, 1991). The relationship between bird abundance and hedgerow characteristics is under investigation as part of a Walsh Fellowship PhD. Results thus far suggest that hedgerow area and the presence of trees influence bird species richness and diversity (Feehan and Flynn, in press). Further research into individual species habitat requirements is necessary before the true impact of REPS can be assessed and recommendations on its modification can be made.
Smaller than sparrows, linnets are often seen in small flocks in winter, flying with fast bounding action and keeping close together. In spring they form pairs. The male has a distinctive rosy patch on the forehead and breast, and both sexes have pale grey heads and rich brown backs.
The linnet depends on a variety of small seeds, such as dandlion, chickweed, sorrel and thistles. They nest in hedges or patches of gorse, not more than two metres off the ground. In winter, some birds migrate to warmer countries farther south. Some remain in Ireland, where they feed in flocks on stubbles and root crops. Encourage linnets by maintaining hedgerows; leaving areas of gorse, blackthorn and bramble for nesting sites and managing field margins to provide annual weed seeds.
Protection and Management
Awareness of the existence of field margins in all grassland and tillage fields is needed. Every permanent field boundary has a field margin, whether a hedgerow, watercourse, stone wall, bank, wooden or wire fence. They offer great potential to improve biodiversity on farms. They can be inexpensive species-rich areas provided harmful practices are avoided, such as the use (often unintentional) of pesticides, fertiliser or slurry. Weed-killers remove the more sensitive natural wildflowers such as cowslips. Then more aggressive species such as cleavers, thistles and nettles colonise. Fertiliser also encourages aggressive species to thrive at the expense of the wildflowers.
Management of Field Margins
- Allow at least 1.5 metres of a field margin
- Avoid pesticides or spray drift
- Avoid fertiliser or slurry
- Allow natural colonisation or seed tussocky grasses such as cock's-foot and yorkshire fog. They smother weeds such as cleavers and barren brome and provide shelter for natural predators like spiders and beetles
- If necessary, use selective herbicides to control cleavers, grass weeds and crop disease. Apply in November and December
Research funded by Teagasc in association with University College Dublin is continuing on methods of improving field margins through a Welsh Fellowship.
Found in areas of moorland or bog with heather cover, the red grouse is rich brown in colour with white stripes on the underwing and a dark rounded tail. The male has a red wattle over the eye. The breeding season is from the beginning of April to the end of June. The nest is built in deep heather. Red grouse normally stay in the same place all year round. Adults feed mostly on heather, bilberry and cotton grass shoots, flowers, seeds and berries. Young are fed on insects for the first few weeks, and then change to the adult diet. Red grouse can be encouraged by the creation of a mosaic of age structures within the heather - tall heather is required for nesting, and young shoots are needed for feeding. Overgrazing and afforestation will both be detrimental to red grouse.
Management to benefit red grouse will also benefit a range of other threatened species. These include hen harriers, who hunt over moorland; golden plover who nest on blanket bog; whinchat, and stonechat.
Protection and Management
Peatlands include raised bog, blanket bog or moors, cut-over bog and fens. Bogs support unique flora and invertebrates. The main issue under REPS is the recognition of these as habitats. Many are target areas such as Special Areas of Conservation or proposed Natural Heritage Areas. Others are not designated target areas.
Under REPS, they are protected from their main threats of land improvement, afforestation and commercial turf cutting. Burning of growing vegetation between March 1st and August 31st is not allowed. This is when breeding birds are present and invertebrates are most affected.
Livestock are essential to the management of upland blanket bogs. Grazing at sustainable levels maintains a varied community of heather, sedges, grasses, ferns, mosses and dwarf shrubs such as bilberry. It also provides the vegetation structure required by invertebrates and small mammals. These in turn provide food for the birds.
Overgrazing reduces the plant diversity. Heathers and other dwarf shrubs are replaced by a restricted range of grasses. Severe overgrazing leads to bare ground and soil erosion. This usually occurs on commonages. Commonage Framework plans are being drawn up by the Department of Agriculture, Food and Rural Development, in agreement with the Department of Arts, Heritage, Gaeltacht and the Islands. These will include a grazing regime, which may include a destocking percentage for the commonage. The grazing regime shall also set out procedures to avoid localised under and over grazing on any part of the commonage.
Measure 2 in REPS (Grassland Management Plan) promotes sustainable grassland management on all grazing areas. This protects habitats, minimises poaching, overgrazing and soil erosion in non- target areas.
Of all the breeding waders, lapwing is the least dependant on wet grassland conditions, breeding on a range of agricultural habitats. They will often nest in arable areas, moving the young to nearby grassland after hatching. Adults can move considerable distances (over 1 km) to find suitable feeding areas. Newly hatched broods can also be moved some distance to the nearest suitable feeding area. Earthworms form an important part of the adults diet. They require a close-cropped sward (less than15 cm) for nesting, as they will only nest where they have good all-round visibility to give them good time to respond to the approach of predators. A low sward is also important for feeding, as both adults and young feed visually, picking invertebrates from the soil surface. If lapwing are present in an area, they will benefit most from light grazing during the breeding season and relatively intense grazing thereafter.
Snipe probe the soil for invertebrates, using the long, sensitive bill. They therefore need soft, damp soil for feeding. They also need tall (over 25 cm) vegetation to conceal the nest. Breeding snipe will benefit more from an absence of grazing in the breeding season and light grazing thereafter. The young are fed by the adults for the first few days, and adults with young will move only very short distances, they are therefore very dependant on ideal field conditions for feeding near to the nest site.
Protection and Management
Wet grasslands include turloughs, river floodplains, lakes fringed with natural vegetation and wet grass fields. These may not all be included in the list of habitats to be retained under Measure 4. The important issue for the REPS planner is to discuss the presence of wetland bird species with farmers. If present, the conditions that prevail suit the birds and should not be altered.
Wet grasslands provide breeding or wintering habitat for waders and wildfowl. Breeding waders found in Ireland include lapwing, snipe, redshank, curlew. They are ground-nesting and raise one brood per year, though most will lay a replacement clutch if the first is lost and conditions remain suitable. Large concentrations of wintering wildfowl can in turn attract predatory birds such as peregrines, merlins, hen harriers and kestrels. Other species also depend on wet grassland to some extent. Skylarks and meadow pipit use the habitat for breeding, while wintering flocks of starlings, thrushes and gulls can feed in large numbers on the invertebrates found in wet grasslands.
Grasslands that retain a high water table in spring and early summer are rich in plants and insects. As the ground is soft, breeding waders can probe for invertebrates such as worms and cranefly larvae. Late winter floods on arable or grassland are valuable. By this time of year, food resources in other wetlands are depleted and females need food to prepare for breeding. Some surface water or pools for feeding is especially important for chicks.
Threats to wet grassland habitats include afforestation, drainage, fertiliser and herbicide use, change from hay to silage, change to tillage and abandonment to scrub. The main threat in grassland is from the trampling of nests up to the end of May. Harrowing or rolling can also cause damage. The presence of mature trees or hedges, which can act as look-out posts and nest sites for predators such as grey crows is not good.
Arable and Intensive Grassland
Skylarks occur widely on farmland throughout the country. They are generally found in open habitats, avoiding trees, tall hedges and bushes. They nest on the ground in pastures and meadows, between 20 and 50 cm tall. If the sward is too tall, the birds will not nest.
The yellowhammer was once a common farmland bird, but its numbers declined in recent years. It is most obvious in spring and summer, when the male has a bright yellow head and breast, and perches on the tops of bushes to defend its territory. The colours of the female are duller. Yellowhammers breed from April to July, with two or three broods per season. In summer, yellowhammers are found in open farmland. The nest is built close to the ground, in thick hedges or shrubs, or on banks. They eat insects and seeds, as well as some fruit in the summer. The chicks are fed mostly on insects. In winter, they form flocks and feed in areas of mixed farmland, particularly stubble fields, where they eat grain and also weed seeds.
Protection and Management
Arable and intensive grassland are not recognised as REPS habitats, but are important for birds. In the past most farms had cereals and potatoes. Specialisation has led to their disappearance in many areas, and the wildlife associated with them.
To encourage birds such as the yellowhammer back to grassland areas of the country, small areas of cereals may be needed, possibly with extra financial incentive. These could even be sacrificed or cut as feed rather than combined.
The switch from spring to winter cereals removes winter stubble fields which provide feeding area and some cover. Cereal stubbles, which contain annual broad-leaved plants, provide food for seed-eating birds such as yellowhammers and linnets. Spraying or ploughing in autumn for spring-sown cereals is equally detrimental. To encourage flocks of wintering skylarks, finches and buntings, as well as game birds, leave stubbles as long as possible, preferably to spring before cultivation. Awareness will allow the farmer to make an informed decision. Skylarks nest in spring cereals. Winter crops are too dense.
Arable and intensive grassland provides feeding for wintering wildfowl such as swans and geese. Bangers disturb them. Wire fences interfere with their flight.
The barn owl is now, sadly, a rare sight in many parts of Ireland. It is generally seen at dusk or while hunting at night. It is honey-coloured above and very white below. In flight, the large wings might make the bird seem quite big, but when settled it is about the size of a wood pigeon. It never hoots, but has a characteristic long, eerie shriek.
Issues for barn owls are nest sites and feeding or hunting areas. If owls are present, conditions in that area are suitable. Other areas may only lack nest sites. To attract owls, put up nest boxes. These are most likely to be successful if the surrounding habitat is suitable for feeding. Barn owls hunt up to 1 or 2 km from the nest, so local conditions impact. Barn owl habitat requirements are not well understood in Ireland. Where they feed on brown rats and house mice, there is evidence that they feed in farmyards and grain stores (this makes them especially vulnerable to poisons). The wood mouse is another important prey species, and it is likely that grassy hedgerows and woodland edges are important.
Nest boxes can be made of wood or converted from old plastic barrels (BirdWatch Ireland has leaflets with instructions and the dimensions for these). They should be sited 4 metres or more high, where they won't be disturbed. They can be fixed in position using ropes or pallet straps. Locked lofts, sheds or tall trees (including prominent trees in hedgerows) are ideal. Woodland edge is better than the middle of a wood. Avoid the sunless northern side of trees or buildings, as these sites can become damp. Full summer sun can cause barrel-type nest boxes to over heat. The east or west side are most suitable, with the entrance faced away from the prevailing wind. In sheds, make sure that cats can't get to the barrel or nest box. The building must be quiet and accessible to the birds all year round.
Check the box annually to see if barn owls are breeding. Late August is best. Visit late in the evening. Never look inside a box without wearing face protection. All breeding wild birds are protected in Ireland, and eggs or young must not be removed from the nest. Pellets are often the best evidence that barn owls are using a nest box. They are 2-4 cm long and up to 1.5 cm wide. They are made up of the fur, feathers and bones of prey and are shiny, greenish-black when fresh. They fade to a dull grey after a few days.
Poisons: Barn owls can be killed by eating small mammals which have eaten poisoned baits. If barn owls are using an area, second generation rodenticides such as Difenacoum, Bromadialone and Brodifacoum should be avoided. Only Warfarin-based rodent poisons are considered safe for use where barn owls hunt.
Swallow and House Martin
Buildings may often hold wildlife that cannot find suitable conditions elsewhere on the farm. While some, like barn owls, will also use hollow trees, others such as swifts, swallows and martins nest almost exclusively on buildings. Important features for birds and bats include eaves, access holes and roof space. House martins nest under eaves. Swallows nest on beams or other surfaces within buildings. Swifts nest inside the enclosed roof space, provided there are gaps under the eaves, through which they can enter.
Swallows are widespread in Ireland, and well known to most people. However, there are some indications that they may be declining in Britain and Ireland. While visiting Ireland in summer, swallows prefer farmland with grazed pastures, meadows and crop, especially where there are suitable nesting areas nearby. Both adults and chicks depend entirely on winged insects for food, such as flies, mayflies and bugs. Their dependence on a mosaic of habitats means that swallows have possibly suffered as a result of the loss of mixed farming with grass and crop rotations in recent decades.
Protection and Management
Under REPS, old buildings inhabited by protected species such as barn owls or bats, are habitats. Disused quarries and such workings, which may have become habitats are also recognised. The important issue for REPS planners is to consider the farmyard as a habitat and discuss this with farmers.
Often minor changes in management can benefit wildlife. The value of buildings and walls depends on design, building materials, age and location. Generally, older buildings situated near less intensively managed land, have a greater wildlife value.
REPS 2000 aims to integrate forestry and REPS. The planner shall identify areas of the farm appropriate for afforestation on environmental, agricultural, forestry and socio-economic grounds. Any afforestation of land shall be designed to provide additional benefits, to offer greater habitat area overall and to enhance biodiversity (Anon., 2000). The following considerations are important from the environmental point of view. Wildlife habitats listed under Measure 4 can not be afforested.
Analysis by Walsh et al. (2001) suggests that commercial afforestation is likely to have an overall positive impact on the population or conservation status of Ireland's avifauna. However, this must be qualified by noting that the more common species are likely to benefit to the greatest degree since many of the most abundant Irish birds can nest successfully in woodlands. Some scarcer species can also benefit from afforestation, for example raptors owls and nightjars (Morris et al., 1994) In contrast, waders and other ground-nesting species of open habitats are particularly vulnerable to negative impacts of afforestation in particular locations (Nature Conservancy Council, 1996).
Walsh et al. (2001) give guidelines for optimising afforestation impacts on Irish birds. Sensitive placement of new forests, taking account of altitude, birds habitats and species distribution are essential to minimising potential negative impacts on Irish birds. Positive impacts are most likely to accrue from discontinuous (non-blanket) afforestation of high quality, low altitude land previously used for livestock grazing, particularly if a high proportion of broadleaved species is included. Mosaics of different tree species and (in particular) tree age classes within a given forest (at medium to large scales), are also likely to produce strong positive impacts on avian diversity (O'Halloran et al., 1998, Walsh et al., 2000). Connectivity with hedgerows would enhance the habitat.
The new Forest Service guidelines on biodiversity (Anon., 2000) specify up to 15 per cent of the area to be left unplanted, as open spaces and retained habitats. Broadleaved species are included. Existing hedgerows are retained. Target areas are not grant-aided for forestry.
As advisers to the farmer, our only aim is to give the best advice possible. We are good at seeing issues from his perspective, seeing the benefits of drainage or land reclamation. It is important for us to consider the bigger picture. If we can increase birds and other wildlife alongside commercial farming, all will benefit. It will be easy to justify agri-environmental schemes. We must try to understand the issues and give farmers the best long-term advice, in the interests of farming and wildlife.
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