Getting close to hen harriers, one of Britain’s most rare and controversial species

Ground-nesters, these birds prefer sweeping valleys of moorland, composed mainly of knee-high heather. Photo credit Sean Gray/www.grayimages.co.uk

A season studying hen harriers in the Isle of Man

Written by Katie Lloyd

I'd been on the island for less than a couple of hours and was already making the well-worn blunder of confusing a distant gull for a male hen harrier. I was comforted to hear that many others make a similar mistake when first getting to grips with the species. Despite seeing the obvious curved silhouette of a gull gliding over the hillside, it just might - you never know - be a male hen harrier hunting the heather moorland. So we check anyway. Apparently, gulls turned out to be hen harriers quite often some years ago. Not now, however - and that's nothing to do with an increase in gulls.

Isle of Man conservationists know too well that hen harrier numbers have declined in the last few years. A study completed in 2007 revealed that 57 breeding pairs were present that year. Since then, residents have noted how their frequent sightings of hen harrier, as they walk the dog or drive to work, have become few and far between. The reason for this drop in numbers is more than a little hazy. Persecution of the species is increasingly well known and portrayed in the media, yet the Isle of Man hen harrier population is allegedly free of persecution. With no grouse shooting on the island, harrier-man conflict is limited: the decline must lie elsewhere. I spent the 2010 breeding season on the island with the aim of helping their main conservation organisation - Manx Birdlife - find out where.

A rare sight
Sitting on a heather tussock in the midday sun, wrapped up in the hat, gloves and fleeces necessary against the Irish Sea wind, I watched a female harrier drift along metres above the rough grassland below her. There is something about the way a harrier hunts. They move gracefully, seamlessly. Floating on, totally unflustered by the weather or the world around them: a sight that few British people will have ever been lucky enough to witness due to their low numbers. It is not just the general public that miss out on this bird. I've met great birders and professional ornithologists who have had very limited observations of the hen harrier, such is their rarity. At the moment - if you have the patience and the willingness to travel - you have the small chance of catching sight of one. It's upsetting to think that in the not-so-far future we might not even have that opportunity at hand. We should be over the moon that we have populations of this bird gracing our country and be doing everything we can to keep hold of it. Firstly we need to know how.

‘Conservation - All meetings and debates?'

This is where conservation research is essential. In most of Britain, conservation of the harrier population comes down to grappling with social, economic and political wills but the likes of the Isle of Man population needs a different type of attention. In Britain, where one could be forgiven for thinking that conservation is all meetings and debates, research is still very much necessary for some of our greatest and rarest species. In this instance the research I was conducting focussed on the success of breeding hen harriers and their nesting habitat; attempting to take into account any land use changes that may have affected their preferential habitat.

The hen harrier
Ground-nesters, these birds prefer sweeping valleys of moorland, composed mainly of knee-high heather. Other specifications come into it as well: many nests are on mossy ground, many near streams and quite often near slopes. Although those three may link together quite nicely another must is the convenience of food and therefore foraging habitat.

Whilst, from reports in the press, you may be lead to believe that all harriers eat is red grouse and pheasants, they actually rarely feast on game birds. Small birds such as meadow pipits make up much of a harrier's diet, alongside small mammals such as voles and rabbits. In fact the population of grouse on the Isle of Man is dismal and the island is devoid of any voles, yet hen harriers have bred here since 1977. This would suggest that the moorland on the island must be bursting with meadow pipits, skylarks and even rabbits. It is these clear sweeps of heather moorland - particularly when mixed with rough grassland - that provide excellent food supplies and it is here that you will have most chance of observing hen harriers hunting.

What to look out for
Whilst females tend to do a decent job of blending in with this habitat, the grey males stand out like a sore thumb. The female, with brown plumage and a buff underside, can be difficult to pick out against grass and moorland but the white band on the tail is something to look out for; a dead giveaway when the sun is shining. A young male - just to make things more confusing - has a similar plumage, with the white-banded tail, and this is where they both get their titles as ringtails. On the other hand, the mature male, thought for many years to be a separate species altogether, is a pale grey with thick black edges to the wing tips - a doddle to pick out, even from some distance, once you've compared with any passing gulls.

This is precisely the reason why the female takes care of all nest-activities. For a male to be seen on the nest is detrimental to the survival of its brood. A slender grey creature in amongst the purple moorland is inviting predators to a free lunch. Whenever the male feels like a bit of home improvement or like helping out with the kids, the female will soon make it clear to him that he needs to get away from the nest - and quick.

Throughout my time with the hen harriers on the Isle of Man it gradually became apparent that a female with chicks is not to be messed with. One or two visits to each nest were made in order to determine clutch sizes and the number of chicks likely to fledge. When the female was present it was soon pretty obvious that she was not happy. Wings arched, eyes burning and talons at the ready, females would readily swoop at the intruder - me. A fantastic spectacle and one that quickens the heart just recalling it. It is suggested that this is not standard behaviour from hen harriers in Britain. Most of those that endure the prospect of persecution tend to slope off from intruders at the nest rather than risk their neck for their young. So in fact, I felt privileged to get so up close and personal with such protective parents. It's just a shame that our other hen harrier populations don't have chance do the same.

Survival in Britain
‘Research is the process of going up alleys to see if they are blind', said Marston Blake - a great American zoologist. Too true. Whilst his blind alleys eventually lead him to help understand yellow fever in North America I was hoping mine would help our knowledge of British hen harriers. So, as well as enjoying every minute of my experience with hen harriers, the research gained a valuable insight into the species. Whilst the study failed to reveal any significant underlying factor for the population decline, it had made the journey down at least one blind alley, eliminated it and simultaneously acquired some valuable data. Data on the breeding success of the population correlated with the preferred nesting habitat; information which can be built upon and furthered in the future. It also pointed out how little we actually know about hen harriers - particularly the Isle of Man population - and how much we assume about them.

New information
For instance, a map highlighting all suitable moorland on the island was said to constitute the island's most optimal hen harrier nesting habitat. Yet, following the recordings of 22 nests, it was noticeable how nearly all of these were present on the periphery of the outlined habitat. Now, why this is we can only guess; closer to a variety of other habitats which may be favourable hunting grounds? Maybe due to the lack of grouse and voles on the island, nearby forests are exploited by harriers for their small bird populations? Or maybe the Isle of Man heather moorland does not contain the accessible abundance of prey that harriers need? Or possibly a combination of the three or possibly nothing to do with them at all. Similarly, why have half of the island's nesting pairs chosen to settle down in gorse when there is deemed to be as much heather moorland as ever? All this is untouched, unknown knowledge, waiting to be discovered so that we can learn how to best help a population that is crucial to the existence of the hen harrier in Britain.

We can't become complacent with a species and its populations and this recent decline has proved that. We need to conserve this population as much as the other populations that suffer from persecution. When we eventually solve the conflicts between the existence of hen harriers on grouse moors and the livelihood of the gamekeepers in the UK, we will need birds from somewhere to inhabit them again.

How Many Hen Harriers in Britain?
When discussing the existing hen harrier population and the hen harrier population as it could - or should be - if persecution was not prevalent, an array of numbers will be banded about. We have 12 breeding pairs in England but we should have 323; we have 489 pairs in Scotland but should have between 1505 and 1790. The British population as a whole has dropped by 20% in 6 years from 806 pairs in 2004 to 646 pairs in 2010. So how do we rectify this? The question is much simpler than the answer and debates between parties have searched for this for years; to little avail. Publications like the Hen Harrier Framework; the recent call from gamekeepers for legalised culling of birds of prey; the attempt to change laws to put the onus on landowners - not the gamekeeper: all of these are evidence to the ongoing controversy that this species causes. And furthermore it points to the perpetual struggle and apparent inability to come to a harmonising solution. With research, with discussion and with positive balance maybe we can get there. Hopefully sooner rather than later.

Back on the Isle of Man, with the data I went for and my return ticket to the UK, I made one last trip to see what had become my favourite hen harrier mum. Despite already fledging three healthy young, true to form she came at me yickering before I was within five-hundred metres of the nest. I managed to snap a photo of her blazing eyes - which is pinned to the wall above my desk now - and watched for a while longer. Watching, wondering and hoping. Surely there's got to be space for this creature in a human world? Surely.