During 2014, two Hen Harrier chicks (named ‘Sky’ and ‘Hope’) were fitted with satellite tracking devices, in an attempt to monitor their progress.
In September, they went missing from their last known location in Lancashire, UK, and have been presumed dead.
Hen Harriers are critically endangered in the UK and Europe, but despite legal protection their numbers are not increasing. There have been suggestions that illegal persecution from the grouse shooting community is contributing to their decline.
Now a new attempt is being made to bring together the conservationists and shooting concerns to resolve their differences.
Professor Stephen Redpath, Chair in Conservation Science at the University of Aberdeen, has agreed to take time out from his latest research in the Amazon, to discuss the project with Decoded Science.
Conflict on the Moors
Although unpopular with some, grouse shooting is a legitimate undertaking, generating significant revenues. Upland heather moors are managed to maximize the number of grouse they can support, through the controlling of vegetation, parasites and predators.
It is the last of these points where Hen Harriers come in. Although they can live in various habitats, their preferred nest-sites are on the same moors as used by grouse (and more importantly managed for shooting).
As Professor Redpath points out “Managed grouse moors would be wonderful habitat for harriers, were most of them not killed. They tend to breed better there (when not killed!) and are more successful at catching food there“.
The reason for this is simple, The high concentrations of grouse chicks on the moors during the breeding season, and the shortage of competing predators (both factors due to the active management for shooting), provide an ‘all you can eat buffet’ for harriers. This has led to accusations that gamekeepers are persecuting and killing hen harriers. The shooting community counter this by pointing to the commercial damage that can be caused by the loss of grouse chicks to predators. They also suggest that other causes (such as disease, accident and other predators) may be responsible for harrier deaths. As each side introduces evidence to support their case, their opponents produce more evidence to refute it.
Applying Science to the Debate
In an attempt to resolve this conflict, the project team has brought together the various stakeholders representing conservation and shooting interests. With the aim of finding agreement on a moorland management approach that could benefit both Hen Harriers and Red Grouse, they are calculating the breeding potential for red grouse on shooting estates, and making projections about the impact of harriers on grouse numbers. The stakeholders agreed on the calculations to be used, and contributed the raw data. Using different projections for the density of harriers breeding on moors, the team were able to estimate the expected losses for grouse numbers. The results showed that:
- If harriers were breeding at a rate of one nest in every 80 sq km (around 30 square miles), this would reduce the grouse numbers by up to 2.5% per year.
- If the harrier numbers increased to one nest per 10 sq km (4 sq miles), the reduction in grouse numbers would rise to nearly 20% per year.
Opportunities for Harrier Management
Hen Harriers are fully protected under UK and European law, but the protection is obviously not working, as numbers are not increasing. Therefore this project is encouraging the stakeholders to consider alternative management methods.
One idea is what is known as a ‘quota system’, allowing a certain number of harrier nests to remain undisturbed upon the grouse moors, but removing excess eggs or chicks to be hand-reared, before releasing them back into the wild. This would allow harrier numbers to grow, while minimizing their impact upon grouse numbers.
The question remains as to who should fund and operate such a scheme, and Professor Redpath admitted that it was “up for debate. If pushed I would favor the main stakeholder groups contributing, but others have different views.” An alternative method would be what is known as ‘diversionary feeding.’ Feeding stations would be set up next to harrier nests, and regularly stocked with carrion for the birds to feed upon, reducing their need to hunt live prey.
Harriers vs. Grouse: A Sustainable Future?
It is probably too late for Sky and Hope, but trial schemes are already operating in Scotland, to manage grouse moorland for both hen harriers and commercial grouse shooting. Legal protection on its own is not working, but there is so far no evidence that a quota system or diversionary feeding would be more successful.
This point was accepted by Professor Redpath, who explained “That is why we need to trial it for 5 years to see if it works.” Nevertheless, the initial results of this study suggest that hen harriers could co-exist with grouse on shooting estates, but only if breeding numbers are managed.
A population density of one or two harrier nests per 80 sq km, could result in a sustainable reduction of less than 5% in grouse numbers each year. There are 2,800 square kilometers (just under 1,100 square miles) of managed grouse moors in England. If agreement could be reached, they could support between 35 and 70 breeding pairs of these rare birds – a significant improvement on the current situation.
In terms of the next stage Professor Redpath advised Decoded Science: “There are ongoing, lively debates. Defra (The Department for Environment, Food and Rural Affairs) have been developing a management plan with stakeholders. Whether that gets agreement we have to wait and see. (The) fundamental debate is between those who favor enforcement to achieve their ends and those who favor a search for shared solutions.“
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