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HALTING DECLINES IN GLOBALLY THREATENED SPECIES:THE CASE OF THE CORNCRAKE
The Corncrake in Decline
In 1830 the naturalist William MacGillivray wrote 'few birds are more common, in so much that there is hardly a patch of yellow iris, or meadowsweet, or nettle or dock, or other tall weed, in which a crake or two might not be found'. Th e decline of the corncrake was first noted in the late 1800's and for over 100 years corncrakes have become rarer and rarer. From being found in every county of Britain and Ireland, their range has steadily contracted back to the north-western fringes, pr i ncipally the Hebrides. Even as early as the 1930s, naturalists were aware of the link between early and fast mowing of hay meadows and the decline in corncrakes. The rate of decline accelerated in the last fifty years and the possibility of extinction bec ame a probability.
Corncrake Research
In spite of the long term nature of the decline, and the striking evidence of the agricultural intensification that has led to its cause, a research programme to find ways to address it was not initiated until the mid 1980s by the RSPB in the Uists. More detailed research was conducted from the early 1990s in the UK (Coll), Ireland, France, Germany and Poland. Together these research findings have allowed a conservation programme to be designed by the RSPB.
Key Research Results
1. The availability of tall vegetation can limit the corncrake population.
Radio-tracking shows that corncrakes need vegetation taller than 20cm that they can easily walk through. Where this vegetation (iris, nettles, cow parsley in spring, hay meadows in summer) decreases due to more sheep and less cattle, corncrakes also decrease.
diagram
The diagram shows the number of singing males from complete censuses in 1978, 1988 and 1993. Counts for 1994 - 1996 covered Scottish Islands that held 94% and 93% of the Great Britain total in 1998 and 1993 respectively, so they have been adjusted by the average of these percentages to allow tar the uncounted areas.
diagram
Changes in the corncrake population of the RSPB nature reserve on Coll following the initiation of a programme of management in 1991 to create new habitat and reduce losses of nests and chicks during hay mowing. The diagram shows the number of singing males in in the reserve (lowest line, filled squares), on the entire island of Coll (open squares) and in the whole of Great Britain (top line, circles). Numbers are plotted on a logarithmic scale so that the population increases or decreases at a fixed percentage rate per year appear as straight lines.
2. Small differences in the timing of mowing of hay and silage can cause large differences in breeding success and population trend. Corncrakes nest on the ground in hay and silage fields with two broods a year. Eggs and small chicks are no match for a tractor and turbo-mower. but by August the rapidly growing chicks are swift runners!
3. Mowing meadows from the centre outwards (corncrake-friendly mowing) causes a large reduction in chick mortality and a large increase in productivity. Cutting to the centre of a field herds the chicks into a decreasing island of tall grass where ultimately they are killed.
4. A female corncrake usually nests and rears her brood within 200m of the singing place of her mate. Females and nests are practically impossible to find but males are very loud, so conservative action during mowing would be effective if applied near to singing places of males.
5. Conservation measures to improve habitats and reduce mowing mortality must be undertaken together.
Research into Action
During the last decade the RSPB has developed an o bjective-led approach to conservation. Priority- species and habitats lbr conservation are first identified and then Action Plans are prepared with clear objectives. such as a specified increase in the numbers or range of a bird species. As a globally thr eatened species in rapid decline, the corncrake is one of the highest priorities for conservation in the UK. To implement the plan to halt the century of decline. and then increase the numbers and range of the corncrake required a multi-pronged approach.
Nature Reserves
Corncrakes are so relatively widespread where they occur that nature reserves can only ever hope to secure appropriate management for a small proportion of their population. However, nature reserves such as the RSPB has on Coll can act as important areas where new conservation techniques can be tried and tested. If successful these techniques can then be demonstrated and explained to other farmers, crofters and farm advisers. Here on Coll the corncrake numbers on the reserve have steadily increased as new techniques to provide and manage habitats have been developed and implemented. The increase from 6 to 30 calling males provides powerful evidence of how the species will respond to habitat management, and the lessons learnt on Coll are spread far and wide. The RSPB now has a series of reserves on Islay, Oronsay, North Uist and Orkney, where corncrake conservation can be demonstrated in a local context and where successfully breeding corncrakes can help repopulate the surrounding area.
Management Schemes
In the late 1980's the RSPB employed fieldworkers on Tiree and the Uists to provide advice to farmers and crofters about corncrakes and to try to persuade them to mow late in a corncrake friendly way. Although the farmers and crofters were sympathetic, they were unwilling to change without a financial incentive. In 1992 the Corncrake Initiative was set up by the RSPB with SNH and the Scottish Crofters Union to provide that financial incentive. Hundreds of farmers and crofters with corncrakes on their land joined the scheme which paid up to £60/ha for cutting hay/silage in August in a corncrake-friendly way. New schemes are being developed that as well as protecting comerakes from direct harm during mowing actually try to positively encourage better habitat by providing corncrake corners where early growing vegetation is present.
Agri-Environment Schemes
The Scottish Office Agriculture, Environment and Fisheries Department has a budget of many millions of pounds to pay to farmers for environmentally sensitive farming practices. The RSPB advises SOAEFD on the most appropriate areas for payments and what the prescriptions should be to claim those payments. The Government is taking the plight of the corncrake very seriously and has set the payment for late cut hay/silage at £180/ha/yr. Since these schemes were set up in the early-mid 1990's, take-up by farmers and crofters has been encouraging. The longer term view of farming in remote areas such as Coll suggests that as production subsidies and prices fall so most farmers will only be able to stay in business if they take due regard of wildlife-friendly farming.
The Results and the Future
Corncrake conservation efforts seriously started in 1992 with the introduction of the Corncrake Initiative and the start of management on the Coll reserve, with the Argyll and the Islands Environmentally Sensitive Area scheme following in 1994. Corncrake numbers hit rock bottom in 1993 with only 446 singing males counted. Then the benefits of the conservation schemes took off. In 1994, for the first time in over 100 years, corncrake numbers actually increased to 463. In 1995, a bigger jump to 542, then to 583 in 1996 and up again in 1997 to 637. The corner seems to have been turned for the corncrake. This species seems to have been brought back from the brink by a concerted conservation effort that depended on the farmers and crofters whose land the corncrakes live on. There are still very few corncrakes and the financial burden of about £350,000 per year has been met largely from the conservation organisations such as the RSPB. All the available data point to changes in agricultural practice as causing the decline in corncrakes. It is now time that the bulk of the costs for corncrake management are met by the Agriculture Departments through Agri-environment measures.
Charlie Self |
