Conservation management of moorland: a case study of the effectiveness of a combined suite of management prescriptions which aim to enhance breeding bird populations
Author(s): Calladine, J., Critchley, C.N.R., Baker, D., Towers, J. & Thiel, A.
Published: January 2014
Journal: Bird Study Volume: 61 ( part 1 )
Digital Identifier No. (DOI): 10.1080/00063657.2013.876615
British moorland can support important populations of breeding waders, gamebirds and birds of prey, underlining its conservation value. Moorland and associated habitats are a result of management, in particular for sheep grazing and sport shooting of Red Grouse. Moorland conservation may additionally be shaped by financial payments made through agri-environment or similar schemes, using management prescriptions to maintain, restore or enhance particular components. While a suite of such prescriptions have been taken up quite widely, an ongoing decline of moorland birds is amongst the more marked results of the 2007-11 Bird Atlas.
BTO researchers, with collaborators from ADAS UK and the former Scottish Coal, have just reported on a ten-year monitoring programme set up to examine the effectiveness of moorland management in south-west Scotland. Management prescriptions advocated widely as best practice for moorland birds began at the site within the Muirkirk and North Lowther Uplands SPA (Special Protection Area) in 2002. These included including muirburn and cutting, grazing, legal predator control and the restoration of hydrological features.
Annual surveys of vegetation and birds were carried out to assess responses to these prescriptions. For birds, comparisons were made against trends for moorland habitats derived from the Breeding Bird Survey (BBS), which accounted for factors such as weather that have a marked effect on moorland bird populations. The expectation that the breeding bird community would increase in response to the management prescriptions adopted was not fulfilled. Only two species increased relative to the general trend for moorland and one of them was Carrion Crow, a species that was being actively removed as part of predation control measures. Most species showed no change or actually declined. Although the responses by vegetation to changes in grazing were quite small, moorland habitat condition did appear to have stabilized and further degradation halted. More relevant, however, was that declines in populations were common across species with different habitat associations, and so a causal relationship with the management changes appeared unlikely. Similarly an effect of disturbance was unlikely, but it remained plausible that the failure to effectively control predators could have contributed to the failure to achieve the principal objective of increasing breeding bird populations.
Although based on monitoring the effects of management prescriptions rather than a controlled experimental design, this work highlights the difficulties in establishing effective management regimes for the benefit of moorland birds. It also underlines a need to develop an improved understanding of the factors that shape moorland bird communities more widely. Raising the question as to whether moorland bird conservation can be effective where they remain vulnerable to predation, it will contribute towards the wider debate on the future of British uplands.
Testing the effectiveness of mitigation for coal extraction activities on moorland
Mitigation of environmental damage is often a condition for the approval of proposed developments. This can take the form of rehabilitation, enhancement, or creation of habitat in or near to the area being developed. Such actions may be legally binding and cost the UK taxpayer millions of pounds. However, the efficacy of these measures is rarely assessed.
From 2002-11 the BTO took part in a study to examine the effectiveness of a suite of management prescriptions designed to increase the numbers of breeding birds in a discrete area of moorland, in order to mitigate the effects of habitat loss to surface coal extraction at an adjacent moorland site.
Several types of management were undertaken to improve the value of the area for moorland birds. These included changes in grazing management, drain blocking and other interventions to improve habitat condition for moorland-breeding birds, and the legal control of generalist predators such as foxes and crows. Data from the BTO/RSPB/JNCC Breeding Bird Survey collected in comparable moorland areas enabled BTO researchers to compare bird population trends on the mitigation area relative to trends on reference sites elsewhere.
Management had little impact on bird populations
Habitat surveys revealed that the condition of the moorland habitat was maintained or improved during the course of the study. Even so, most bird populations either declined or failed to respond positively to this carefully devised regime of management. Evidence from the study suggested that ineffective predator control was an important causal factor. This was probably due, in large part, to reduced levels of control on land adjacent to the study site from 2004 onwards.
The importance of predation
Predation is a natural process and is integral to ecosystem functioning although, in some contexts, increasing generalist predator populations may threaten species of conservation concern. The conservation of some moorland bird populations may therefore be enhanced by the control of those predators. A better understanding of how and where predation affects bird populations could help to improve the efficacy of conservation measures. This study represents a rare example of industry-sponsored monitoring to inform conservation management, and should be replicated elsewhere to help our understanding of how to mitigate any negative environmental impacts of development most effectively.
Assessment of outcomes is vital
To ensure the delivery of proposed conservation objectives, the outcomes of management prescriptions must be examined critically. This enables policy-makers, practitioners and regulators to learn from failures, as well as from successes. In the long term, studies such as this one, which also relied upon the availability of long-term BTO monitoring data, will help to make conservation management more robust.
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