Trip reports
Indoor Meeting: CORN BUNTINGS AND OTHER FARMLAND BIRDS OF EAST SCOTLAND
Tom Marshall (rspb-images.com)
Tuesday, 24 February 2009
Nineteen species are classed as farmland bird indicators, of which seven, such as the Rook,are rated as generalists and twelve, such as the Tree Sparrow, Corn Bunting and Yellowhammer are considered to be specialists.
Taken together, farmland birds have declined by 50% in the past twenty-five years. The generalists are holding their own while the specialists have shown the greatest loss in numbers. Various reasons for the decline have been identified. There is a less winter food available as there is less spring-sown cereal and hence less winter stubble. More autumn-sown cereals means crops are growing over winter, resulting in a habitat poor for foraging. There are fewer mixed farms so diversity of food sources is reduced. Autumn sowing of cereals also means that the density of the plants is too high at nesting time for species such as Skylark and Lapwing.
In Britain the general pattern of farming is intensive cereal cultivation in the east and livestock production in the west. Lack of cattle feeding outside is disadvantageous as ground is disturbed and broken up by their hooves, making soil invertebrates more accessible. More efficient use of pesticides reduces the availability of insects. Improvements in drainage have resulted in loss of the wet areas which passerines and waders need as a source of insects. Removal of rough vegetation means loss of insect-rich habitats and also areas suitable for nesting for species such as Skylark.
When farmers managed their own land they often knew the location of nests and would move them from the path of the plough. Now management, such as silage cutting, is often done by contractors who have to get the job completed as speedily as possible to make it cost-effective. This can have a negative impact on birds nesting in such crops.
But this part of Scotland has more diversity than in the general pattern of Scottish agriculture, with more mixed farming, including cattle rearing and a mixture of spring-sown and autumn-sown cereals. Farming is still fairly intensive but yields a good range of habitats because the ground is poorer than further south and includes more marginal land sometimes not brought into production. In 2007 the distribution was 27% cereals, 23% beef, 15% potatoes and with less than 10% of each of sheep, pigs, poultry, rape and dairy.
The Curlew needs a mixture of rough tussocky vegetation and wet areas where it can probe for insects and worms. In the past fifteen years the population has declined by 87% in the Southern uplands. This is attributed to increased drainage and improved grassland.
The Lapwing requires broken ground [so spring-sown cereals are important], closely-grazed grassland and wet areas for feeding. It may nest in fairly dry fields then lead the chicks to wetter areas. Like the Curlew it moves to the coast in winter. Since 1994 there has been an 18% decline in Britain. But in parts of the north-east of Scotland, where there is a lot of spring-sown barley and moorland farms, the number has been stable since 2003 and even increased in some areas.
The Redshank, which feeds on insects that are below the surface in wet grassland and depends on a varied-structured sward, is a difficult species to manage. Since 1994 there has been a decline of 12% in Britain. There are no figures for Scotland but there probably has been a considerable decline. The Redshanks seen on the coast in winter are mainly immigrants from Iceland and the continent.
The Buzzard, which in the early 1980s was an upland bird, is now widespread over the north-east.
It is the ultimate generalist, eating almost anything, including juvenile Rooks, but greatly helped by the numbers of Pheasants killed on the roads and by the increase in the rabbit population after the
reduction in the their numbers from myxomatosis. Besides, humans no longer kill them routinely.
There is a lot to learn about Barn Owls. Their diet is rodents and their numbers have declined with the reduction in habitats suitable for their prey. Field verges are good rodent habitat and farmers can be paid to maintain them but this may produce less income than using the whole field for crops. Some Barn Owls are killed by cars when hunting along roadside verges.
The Grey Partridge has declined dramatically in Britain. It requires winter stubble. It nests in a ditch or at the bottom of a hedge and during the summer may feed in the narrow strips at the edges of cereal fields. Its needs are fairly well understood as are the changes required to provide for them. It has declined in Upper Deeside where cereals and winter stubble have been replaced by grassland for livestock. Being sedentary they cannot survive in an area unless a winter food source is available. The numbers are also reduced on the RSPB monitored farms since 2003.
In Britain as a whole there has been a greater than 50% decline in Skylark numbers in the last twenty-five years. It nests in spring barley or in grass fields where grass cutting can destroy nests. To maintain the population, Skylarks need to make two nesting attempts annually. In contrast there has not been a significant change in Scotland and the species is widespread in the north-east from the hills down to the coast. The Skylark needs a similar habitat to the Grey Partridge but can survive where the Partridge cannot as, unlike the Partridge, it migrates to the coast for the winter.
Since the early 1990s Tree Sparrow numbers have declined by 90%. But they respond well to management and are now increasing, largely due to conservation efforts such as providing nest boxes, feed and wet areas where they can forage for food for the chicks. In the past twenty-five years there has been a large increase in numbers in Aberdeenshire which is probably the best place in Britain to see them, with winter flocks of up to a hundred. In the Loch of Strathbeg RSPB Reserve area they were seldom seen in the late 1990s. In 2003 nest boxes and food were provided and there are wet areas that provide food for the young, so now there are counts of fifty or so adults, and breeding success is good.
Since 1994 there has been a 15% increase in Yellowhammers in Scotland. They are widespread in Aberdeenshire although here there has been a small decline in the uplands. Like the Grey Partridge it has disappeared from Upper Deeside, and for the same reasons - it cannot survive the winter as it is sedentary and there is a lack of cereal crops that would provide winter feed.
The Reed Bunting, which has similar requirements to the Yellowhammer, has increased in numbers recently after a decline. This is probably due to it nesting in oil seed rape and also in response to agricultural management schemes.
The Corn Bunting has declined greatly in Europe. In Scotland the population has fallen to perhaps about eight hundred singing males. Like other buntings it feeds on grains and weed seeds and needs stubble fields in winter. Hywel has been involved in research into the Corn Bunting and its habitat requirements. Corn Buntings are ground nesters, laying first in grassland in late May and early June and later in cereal crops. The males are polygamous although most are monogamous in Tayside. Hywel has recorded a male with five mates but has been told of an even more enterprising individual that had eight partners. The chicks can leave the nest when they are as young as seven to nine days old when they are still flightless. There has been a contraction in range in lowland Scotland, with the main strongholds now in the western isles and in the east. There are about one hundred singing males in the Western Isles, about fifty in Tayside, about five hundred in north Aberdeenshire and a small population in south Aberdeenshire. In one area of South Aberdeenshire one hundred and thirty singing males were recorded in 1990; the latest count was eleven. The first nests in late May and early June are in dense grassy habitats which protect the nests from the elements and conceal them from predators. Much of this grass is cut as silage, with the first cut in the middle of June. It is cut very short, not only destroying about 80% of the nests but chicks which have left the nest may be killed. Traditionally in the Western Isles the crops were cut when ripe and fed to the animals in winter, but now cereals are cut when unripe, and stored in black bags for winter feed, as farmers like to get crops in early since Greylag Geese devastate crops. The early cutting results in unripe seeds which have a lower nutritional value than ripe seeds. In Aberdeenshire the winter stubble is a good source of food.
In 2001, in the Western Isles, a trial scheme was tested in which feeding platforms were attached to posts and stocked with cereal seeds. These attracted competitors in the form of Sparrows and Starlings as well as the odd Merlin looking for an easy meal. In 2003 over thirty crofters were paid to stack part of the ripe cereal crop in the fields. This resulted in some areas being recolonised and an increase in the population by 2007, but for some unknown reason it fell in 2008. In 2009 there is to be a trial of sowing various mixtures of grasses and leaving them over the winter.
In the work that Hywel has been doing in the east of Scotland, various management options have been investigated. Where these have been implemented the population was stable but in other areas there was a 43% decline. Since 2005 on monitored farms there has been an increase in singing males and, of course, if the right conditions can be arranged for Corn Buntings, these will also be right for other species such as Yellowhammers. Cutting grassland later also protects Meadow Pipit and Skylark nests.
The key to success is the attitude of farmers and crofters who have to be persuaded to participate in various schemes. Both Scottish National Heritage and the Scottish Government realise that the Corn Bunting could face extinction and have provided funds. The proposals to save the Corn Bunting must be integrated into a national Agricultural Scheme in which farmers are paid to maintain the biodiversity of habitats. Various options must be presented to farmers from which they can choose the best suited to individual circumstances.
After the expenditure of much effort and resources, Corn Bunting research has identified the causes of decline. This research must be translated into effective recovery strategies workable by farmers. Farmers needs help by planners in drawing up their schemes which, when put into practice, must be monitored to check that they deliver their objectives. This will be costly as funding must be found to recompense the farmers, the planners and the monitors.
This was a masterly talk, well organised, well illustrated and well delivered. There was an excellent turn-out by an appreciative audience. And if you wish to see a Corn Bunting, Hywel recommends the area round Strathbeg.