The Hen Harrier

by Donald Watson

  Fig. 14 Aggregates of monthly peak counts of Hen Harriers

  during eight winters at Roost 1

  Departure from the roosts

  Harriers were seen to leave Roost 1 between 53 minutes before, and 47 minutes after, sunrise. The majority left before sunrise. Departures from Roost 2 had later averages, the earliest recorded by Dickson being 20 minutes before sunrise and the latest 45 minutes after sunrise. It was generally difficult, or impossible, to obtain satisfactory counts in the morning at Roost 1; ringtails were particularly difficult to spot as they flew above the brown grass in dim early light, and mist in the valley was sometimes a further handicap. Most of the birds left the roost area quickly, and dispersed in different directions. They rose a few metres into the air above their roosting sites, often shaking their feathers, and either proceeded in direct low-level flight, or circled to a considerable height and drifted away more slowly. Once, a ringtail which had risen from the roost flew for a short distance and dipped to disturb another ringtail, as if chasing it out of bed. When first rising, the birds sometimes seemed, literally, to jump out of cover. Twice, a male and a ringtail kept close together as they flew away and, once, two ringtails behaved similarly. On 24 December 1975, I followed the course of six departing birds as far as possible; they fanned out in every direction except due west and gave the impression that they all had pre-determined routes to their hunting grounds. On another occasion, proof was obtained that one ringtail hunted within one to two kilometres of the roost; it was still hunting in this area an hour and a half after rising. A few birds perched and preened for some minutes—once for as long as an hour—on rocks or hillocks overlooking the roost. At Roost 2, Dickson saw up to six birds perched together on fence posts and rocky outcrops before they left the roost. They generally flew off singly but he once saw three males leave in the same direction and, another time, four males and four ringtails left together.

  Fig. 15 Aggregates of monthly peak counts of Hen Harriers

  during eight winters at Roost 2

  Dispersal from the roosts

  In the absence of colour-marked birds it is impossible to say with certainty how widely the harriers dispersed from the roosts during the day. During November 1971, a bird which appeared to be a first year male, with prominent light patches near the carpal joints of both wings, was thought to be carrying wing-tags. On 12 December 1971, a first year male which had been ringed and wing-tagged by Nick Picozzi in Kincardineshire (240 kilometres NE), in July of the same year, was found dead near Roost 2. There was obviously a possibility that the same bird had moved from one roosting area to the other. There was a sharp decline in the number of hunting birds seen at more than six kilometres from Roost 2, compared with a majority of sightings between eight and twelve kilometres from Roost 1. This difference probably reflected the relative accessibility of good hunting grounds. Many observations were made of harriers, travelling towards Roost 1 in the evening, at places up to sixteen kilometres distant.

  A ringtail with distinctive wing pattern, previously seen at the roost, was recognised by Louis Urquhart at a point more than nine kilometres away. One November evening, I watched a ringtail hunting over a large reed-bed, at twelve kilometres from the roost; flocks of Starlings were gathering at the time and seemed an obvious attraction as prey, but after spending ten minutes coursing over the reeds at high speed the harrier suddenly turned away, at twelve minutes past sunset, and set a deliberate course towards the communal roost. It could have found a very similar roosting site—but liable to disturbance by shooting—in the big reed-bed which it had been hunting, but the pull of the communal roost was evidently irresistible. The Craigheads found that Marsh Hawks dispersed up to at least nine kilometres from a roost; almost certainly harriers from Roost 1 sometimes dispersed to more than sixteen kilometres.

  The atmosphere of a roost (Roost 1)

  For an hour or so towards the end of a short winter’s day, a watcher can break all ties with the world of human affairs and enter another ‘under the heavens that know not what years be’, which is the world of wildlife. I often wondered how far back in the distant past harriers had first discovered and made use of the flow for roosting. There was something about the slow pageant of their gatherings which contributed to a sense of timelessness. Watching the final moments of the harriers’ day seemed to underline how little I knew of their total activity. As I have said, most birds arrived well gorged from a recent meal, but how rarely on daytime excursions in the surrounding countryside had I observed one making a kill! Once we spent a full November day in neighbouring country without so much as seeing a Hen Harrier until, at dusk, twelve flew in to roost. Even on extensive wanderings it was unusual to see more than one or two hunting birds. Although the sight of harriers gathering to roost became a familiar spectacle, I was always aware of the unfathomable gulf which separated their identity as living creatures from ourselves. Often as we turned for home, after a drenching watch, and left the birds to sit it out for another 15 hours or more of darkness in their roofless beds, I thought of the marvellous protection which feathers must provide. Occasionally, some slight observation added an unexpected detail of knowledge, as when, on 26 November 1975, a ringtail showing one or two short dark central feathers in a faded tail revealed the extended period of moult.

  My recollections of incidental activity at the roost are dominated by a sense of seasonal rhythm. On soft September nights, Swallows and Pied Wagtails flickered over the marsh and drab-plumaged Mallard and Teal guzzled under the stream bank. From mid-September, the first menacing roars of rutting stags were heard from the depths of the forest. Sometimes, in October’s Indian summer, the evenings were warm enough to bring up clouds of midges, but roost watching generally ranks as one of the coldest forms of inactivity, not to be recommended to anyone inclined to restlessness or impatience. November dusks were full of the sweet wheezing and chuckling of Fieldfares and the sharp calls of Redwings. Then, too, we listened for the calls of approaching flights of geese, or heard the clear bugling of Whooper Swans as they flew, silhouetted against the sky, towards a distant loch among the hills. Beyond the tall heads of withered grasses, Goldeneye patrolled the open water in bunches of five or six; later in the winter we heard the whistle of their wings long into the dusk as flight followed flight, to roost in company on a loch. Goosanders fished the stream or sped overhead, signalling alarm at sighting us by their guttural barking. Scanning a distant skyline for incoming harriers might result instead in a glimpse of a Golden Eagle planing slowly to a distant roosting place, or even of a Kestrel still hovering above the moor. I have already mentioned the predators most often seen, in addition to the harriers; strangely, although Buzzards had at least two territories quite near, and regularly roosted in the forest, they scarcely ever appeared over the harriers’ roosting ground and we never saw any conflicts between the two species. Once, on a November morning, a Great Grey Shrike obligingly chose the only willow bush in view as a hunting perch.

  For several winters, a Green Woodpecker could almost be relied upon to give a short burst of its laughing cry before it retired for the night in one of the old birch trees in the forest. In the earlier years, otters were seen with some regularity; once we were greeted by one in full view on a mid-stream boulder. At all times we were aware of the small resident birds of the spruce forest—Goldcrests, Coal Tits and Wrens—from their calls and rustlings among the needles, or the whirring of their tiny wings close beside us.

  The virtual silence of mid-winter watches began to be broken, from late February or early March, by the songs of birds which returned to breed in the forest or on the flow itself. The coming of spring was marked, above all, by the arrival of the Curlews which soon began to make song-flights over the harriers’ roosting ground. There was generally little sign that either resented the other’s presence. Among all the sounds which heightened awareness of spring, none were more pleasing to hear than the songs of Blackbirds and Song Thrushes from the forest above. As we
trudged back from our stance, with the last glow in the western sky, Tawny Owls hooted and Woodcock, lisping and croaking, almost clipped the tops of the conifers on their roding flights.

  Reasons for communal roosting in the Hen Harrier

  The habit of roosting communally occurs in a large variety of birds. Some of the most spectacular examples, cited by Wynne-Edwards (1962), are found in such differing groups as Cormorants, ducks (Goldeneye), parakeets, Swifts and Swallows, gulls, waders, birds of prey and passerines. In some birds such as Starlings, gulls and many waders, the habit is one of the most arresting features of their winter behaviour, while in others it can easily be overlooked. The usually solitary-roosting Robin, for instance, has been shown by Swann (1975) to be a communal winter rooster in some districts, while Birkhead (1973) regards the diurnal ‘standing grounds’ of Grey Herons as an example of communal roosting. Although the habit appears to be commonest in species which also feed gregariously, it occurs in a number of birds which are usually solitary feeders. Among these are Wrens, Tree Creepers and Grey Herons, as well as raptors such as the Californian Condor, Turkey Vulture, Rough-legged Buzzard and the harriers.

  Differing theories have been offered to explain the function of communal roosting. Lack (1968) regarded the main purpose as protection from predators. Wynne-Edwards (1962), on the other hand, concluded that ‘the primary function of the habit was to bring members of a population-unit together so that they could hold epideictic demonstrations resulting in adjustments of population density through emigration’. Ward and Zahavi (1973) argued that the roosts provided a centre at which information on the location of food within the area served by the roost might be obtained; for solitary feeders this could apply ‘to the position of good feeding places in relation to the roost, not to the position of the food itself’. Zahavi (1971), however, had differentiated birds, such as Wrens and Tree Creepers, which evidently form temporary crowded roosts for warmth in cold weather. Among harriers, the habit was associated with preparation for migration, by Meinertzhagen (1956) and also by Gurr (1968); but in his study of Australasian Harrier roosts in New Zealand, where this harrier is not migratory, Gurr concluded that communal roosts could facilitate pairing, and might also be a means of providing information for population adjustments, in the manner suggested by Wynne-Edwards.

  How far, then, do my own observations in south-west Scotland support any of the above, or different, explanations? Certainly there was evidence that the close proximity of roosting birds enabled them to respond rapidly and communally to suspected danger. Although, in historically recent times, communal roosting has undoubtedly increased the birds’ vulnerability to man, the habit must be considered in relation to an earlier situation when the chief danger must have come from other mammals. It can hardly be doubted that solitary roosting would increase the danger in this context. The preference for boggy locations (not universal in Hen Harriers) is no doubt a response to the need for safety against predators, but it might be associated with communal or solitary roosting. It may be argued that the perching and soaring in groups, which often took place before roosting, is consistent with Wynne-Edwards’ theory; yet the virtual absence of such behaviour on days when hunting conditions seemed to be worst, must be noted. I find it difficult to understand how even the maximum amount of social flying or perching which was seen, could be regarded in the same light as the elaborate pre-roosting evolutions of birds such as Starlings. Certainly, the open nature of the roosting grounds and, sometimes, the high flights and conspicuous perching of the harriers give good mutual observation, and there are many indications that some birds (females and older birds) have precedence over others (males and younger birds) at the roost. Birds of ‘inferior’ status might then be kept out of the best sites and come under pressure to move elsewhere. It seems very likely that by noting the flight lines of birds arriving with full crops, other harriers, which might include new arrivals in the district, could learn the whereabouts of good hunting areas. Observations of one bird following another, either to or from the roost, also support the idea of the roost as an information centre.

  The communal roosts of finches, Starlings and other passerine birds certainly attract numbers of predators, such as Sparrowhawks and Merlins, and it is difficult to believe that they have a safety advantage. If dangers from modern man are discounted, ground roosting harriers could well be most secure in company, but this may not be the basic reason for roosting together. It seems to me very likely that this behaviour has a primary social function. Roosts may provide staging points in an essentially nomadic winter existence, enabling contact to be made between birds which are experienced and those which are inexperienced in utilising the food resources of a region. Additionally, the roosts appear to give opportunities for males and females to associate in winter and probably to form pairs. There is some evidence that Hen Harriers from widely separated natal regions may interbreed (Chapter 7) and it seems reasonable to suppose that this mingling of populations may arise partly, at least, from association in communal winter roosts. The occurrence of a marked bird from Kincardineshire in one, and very possibly both, roosting areas in south-west Scotland is of interest. Now that an increased number of Orkney Hen Harriers have been colour marked by Nick Picozzi, in 1976, there must be a real chance that some of these birds may be recognised at roosts*, or as breeding birds, as far afield as south-west Scotland, or even much further.

  * See Chapter 7. On 24 October 1976, a ringtail, which must have been wing-tagged on Orkney in 1975, was recognised at Roost 2 by R. C. Dickson.

  CHAPTER NINETEEN

  The Hen Harrier: A Controversial Bird

  Whether or not Hen Harriers continue to inhabit this world is a matter of indifference to the great majority of mankind. When, in 1544, Dr William Turner said that among our countrymen it gets its name from butchering their fowls, it may be supposed that Hen Harriers were commonly disliked by a predominantly rural population. Nobody now knows to what extent they preyed on free ranging poultry, but very little has been heard of this habit in modern times.

  The general reduction in suitable habitats for harriers must prevent any likelihood that they will ever compete with man’s essential food requirements in the future. Yet, in countries such as Britain, where a small but influential section of the population is intensely keen on game shooting, birds of prey are often still treated as vermin, and the Hen Harrier is apt to be placed in the forefront of this category. The precise meaning of the word, ‘vermin’, so beloved of writers and advertisers in shooting periodicals, is hardly ever defined. No doubt it will be argued that it ought to refer only to those animals which have been proscribed by law as pests, but any country dweller knows that within the comparative privacy of some shooting preserves the fate of protected species depends on the opinions of landowners, sportsmen and gamekeepers. I have many good friends who enjoy shooting, and I do not for a moment suggest that the majority kill protected species, but what happens to a Buzzard on a Pheasant shoot, or a Hen Harrier on a grouse moor, is undoubtedly more likely to be decided by personal opinions of the damage or disturbance it might cause to game, than by a consideration of its status under the law. I recall, for instance, speaking to a friendly gamekeeper when Hen Harriers had begun to re-establish themselves in my own district. His reaction was that he would have to see ‘what they did’, with the implication that if he found any evidence of grouse killing he would take what he considered appropriate action.

  Every year I hear that Hen Harriers have been ‘taken care of on grouse moors in south Scotland and I have already described how I found pole traps (illegal since 1904) set on one of these a few years ago. I mention these examples only to corroborate that the decision whether or not to destroy such birds is often made irrespective of the law. I am not, at this point, making any judgement on the effect which Hen Harriers may or may not have on grouse stocks or on the conduct of a grouse shoot. It is, I think, essential to spell out the meaning of the Protection of Birds Acts, in
regard to the Hen Harrier and other First Schedule species,* as it does not always seem to be fully understood - I cannot do better than to refer to the booklet Predatory Birds in Britain prepared by a working party which included leading representatives of the Game Conservancy, the British Field Sports Society and the Gamekeepers’ Association, as well as the National Farmers Union and major fauna preservation and protection bodies. I quote from this: ‘The Protection of Birds Act, 1954, contained no provisions under which First Schedule birds (all rare or relatively rare) might be legally killed as pests, but Section 8 (1) of the Act of 1967 provides for the issuing of licences to kill First Schedule species where necessary “for the purpose of preventing serious damage to crops, vegetables, fruit, growing timber or any other form of property or to fisheries”. It is necessary to emphasise, however, that farmers, game preservers and landowners are not allowed to take direct personal action under this provision. The intention is that those who experience damage to crops, stocks or property by First Schedule birds should report this to the Secretary of State, and that the claim should be investigated before any decision is taken as to whether control measures are necessary. (Game species in the wild are not regarded in law as property).’ It is therefore quite clear that the killing of wild game birds, such as grouse, by a Hen Harrier could provide no legal grounds for its destruction.