Mark writes: I don’t normally publish anonymous guest blogs but in this case, knowing the circumstances, I can see why the person wishes to remain anonymous. And the text stands on its own. See also this recent blog on the same subject, from a different perspective, by our friends at Raptor Persecution UK.
The New Killing Fields – Why encouraging crop-nesting hen harriers defies logic
This year, Natural England will commence its project to create a population of arable-nesting hen harriers in southern England. The aim here is to encourage hen harriers to nest in cereal crops, as hen and Montagu’s harriers do in parts of Spain and France. Because UK hen harriers prefer to nest in the heather dominated uplands, and young birds fledged from such habitats will look to nest on heather moorlands, not arable, Natural England has reportedly decided to source its birds from arable areas in Spain or France. Being derived from an arable-nesting population, these translocated birds should thus nest in cereals in the England translocation area, rather than wandering off in search of heather moorland.
A big problem with this approach is that hen harriers nesting in cereal fields tend to fail without active human intervention. Farm operations destroy nests. Increasing the range of a species of conservation concern is a sound conservation strategy; deliberately inducing a species vulnerable to agricultural operations to nest in arable fields isn’t sound – it’s reckless.
In fact, the conservationists working to protect arable-nesting hen and Montagu’s harriers in Spain and France say their efforts have created a ‘conservation trap’. They have succeeded, through costly interventions, to protect some hen and Montagu’s harrier nests in arable from farm operations. But as the hen harrier population has increased in these arable landscapes, the costs of protecting them has mushroomed. Today, these arable nesting populations are only viable because field workers monitor the population, locate nests, then intervene when farmers undertake operations.
The dubious ecological- and cost-effectiveness of this situation is analogous to the Wessex and Breckland arable nesting stone curlew population. This population has increased but so too has the cost of ensuring their safety and providing safe nesting plots in arable fields. In fact, Natural England has progressively cut funding for stone curlew conservation due to spiralling costs as the arable nesting population has increased. All this in the very same place they now plan to create an arable-nesting hen harrier population.
And hen harriers are likely to be even more costly: at least stone curlews can be induced to nest within relatively safe bare tilled plots in arable fields. Hen harriers of course nest within the cereal crops themselves, not on safe plots. If the translocated project is to succeed, Natural England will need to intervene to ensure cereal nesters remain safe from crop treatments and harvesting operations. There’s probably no such thing as a safe, self-sustaining hen harrier population within arable – if after, say, ten years, Natural England switched off funding for nest protection, nests in arable will be destroyed, and the southern England hen harrier population will probably decline.
It seems very likely that Natural England funding to safeguard arable-nesting hen harriers will not be sustained for the long-term: as the stone curlew population in the same area has increased, Natural England has slashed funding.
It’s difficult to think of another arable-associated species that is more vulnerable in intensive arable plains than the hen (and Montagu’s) harrier, yet Natural England is intent on creating just such an intervention-dependent population. This defies logic.
Refs:
D. Torres-Orozco et al., (2016) From a conservation trap to a conservation solution: lessons from an intensively managed Montagu’s harrier population https://pubag.nal.usda.gov/catalog/5879327
Cardador, L., et al., (2015) Conservation Traps and Long-Term Species Persistence in Human-Dominated Systems https://onlinelibrary.wiley.com/doi/full/10.1111/conl.12160
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