The Hen Harrier

  The burning of much of the oldest heather in 1960 had already reduced the choice of good nesting sites and there was evidence that several nests were poorly concealed. This might not have been a serious disadvantage had it not coincided with increased human disturbance. In such a small area of open country any human activity, including harrier watching, could possibly unsettle the birds in the early part of the season. Geroudet considered that Hen Harriers in France became accustomed to farm workers in the vicinity of nests, and it is probable that they similarly accepted the shepherd and his dogs on their regular rounds.

  The ploughing and planting of about 500 hectares (about a third of the area) in 1966–67, with later work on fencing, undoubtedly caused additional disturbance and temporarily reduced the amount of suitable ground for nests.

  Persistent attacks by harriers on the Golden Eagles, which were over the nesting area almost daily from 1965 onwards, suggest that they may have had an unsettling effect; and the presumed killing of a female harrier by an eagle, in May 1968, may have prevented nesting on the moorland that year.

  The cessation of moorland nesting may have been largely due to the fact that much nesting cover in adjoining forests reached its most suitable stage between 1965 and 1970.

  CHAPTER TWELVE

  Forest Nesting: 1965–75

  In the first half of the 1960s, Langley and Madelaine Roberts regularly scoured the most promising forest areas for nesting harriers and other birds, while I spent more time on the moorland. Later, as moorland nesting faded away, I also spent much time in the forests, alone or in company with other enthusiasts, especially Louis Urquhart, my son Jeffrey, Dr John Selwyn, Dr Ken Brewster and Michael Williams. Much helpful information was given by foresters and rangers and in later years, ornithologists, such as Dick Roxburgh, Richard Mearns and Mick Marquiss, who were primarily concerned with other predators, helped me by reporting all sightings of harriers. Many others contributed useful observations.

  During the 1950s and early 1960s, most of Areas C, D and E was planted with conifers, mainly sitka spruce and lodgepole pine, with a fair amount of larch and smaller quantities of other species. In these years, road-making was an important part of forestry activity, involving fairly continuous lorry traffic. Although Hen Harriers were occasionally seen in the forests from 1958, the only proved nesting before 1965 was in 1962, on unplantable ground, as described in the moorland section (Chapter 11). The area was probably less suitable for nesting in the early period, partly because of disturbance by ploughing, planting and road-making but, more importantly, because in the very young forests there is much less concealment for nests.* Although the optimum period for forest nesting was undoubtedly when the trees were 6–12 years old, there was much variation in the height of trees of any age-group and it was found, in Area E particularly, that harriers could still find sites in 14–15 year old forest, where most of the trees were 3–6 metres tall, but the canopy was by no means closed up. No nests were found in forest rides although many of these appeared to have suitable sites in deep heather and grass.

  After the moorland experience many new lessons had to be learned about harriers in a forest environment. The advantage of often being able to use a car as a hide in locating pairs or nesting areas was offset by the much greater difficulty in pinpointing sites. Many times a food pass might be seen but trees made it impossible to follow precisely where a bird had gone to ground. Initial observing, as on moorland, had to be done from a commanding viewpoint to avoid losing sight of the birds in dead ground, and this often involved watching from at least a kilometre away. When a hen went down to a nest site, great attention had to be paid to ‘marker’ features such as dead trees and rides which might help to identify the spot later. In June and July, flies and midges were often almost unendurable in the heart of the young forest. The final search for a nest which entailed negotiating furrows, folds and waist high heather, with constant warfare against sharp sitka needles, was no doubt made sufferable only by some elemental hunting urge. In blocks of uniform forest it is easy to become disoriented and many a search foundered at the first attempt when, at close quarters, marker trees could not be re-discovered and every part of the forest seemed alike.

  At first, after the spaciousness and varied colours of the moorland, so sensitive to seasonal change, I had no liking for the forest with its oppressive, repetitive landscape. In time, as I came to know it in all its moods, it sometimes cast a quiet and mysterious spell. I often had the feeling that the trees concealed secrets. It was good country for observing without being observed, and there was never a day in search of harriers which did not bring a harvest of incidental sightings—a roe doe with speckled calf, a monstrous red stag in a ride, or a fox, like a flash of gold and silver against the dark underbrush of the forest edge.

  Bird song on May or June mornings was a revelation of high breeding populations of Robins, Wrens, Willow and Grasshopper Warblers, Redpolls and Song Thrushes. In one harrier territory, a Song Thrush included a deceptive mimicry of the harrier’s food call in its song phrases. Often the soothing sound of Blackcock in display carried from a distant lek, and Cuckoos called almost as ceaselessly as on the moorland.

  In the young plantations, Short-eared Owls were again the harriers’ neighbours. Barn Owls, more creamy-white than cock harriers, left their nesting places in former shepherds’ houses or rock cavities to hunt conspicuously, by day, among the dark trees. Until their weaker, fluttering flight and rounded wings were observed they could be momentarily confused with a cock harrier in the distance. Kestrels were never far away and a few Merlins nested in the deep heather on unplanted rocky slopes, while Buzzard, Peregrine and Golden Eagle sometimes passed overhead. The Black-headed Gulls, which continually journeyed between lochside nesting colonies and distant fields, were the jokers in the pack, looking enough like slim cock harriers when far away, to raise many a false hope.

  If all this suggests that the forest was an idyllic haven for wildlife, the impression needs qualifying. Jet aircraft often roared just above the trees and sometimes a helicopter spraying fertiliser droned and spluttered for days on end. The forest, of course, existed for timber production. Rangers were under orders to shoot many of the red deer which, it was feared, increasingly damaged trees by stripping bark. Roe deer were fairly heavily culled and foxes were snared or shot. Among birds, only crows were generally destroyed, but pheasant and grouse shooting was let, and there was always a possibility of illegal destruction of predators on this account. Most importantly, the majority of the bird species which flourished while the trees were small were doomed to disappear within 10–20 years as the forest closed up and grew taller. Others would replace them, but there would eventually be less variety of species. As new plantations appeared, the Short-eared Owls and harriers might find alternative breeding sites in them for a few years, but I was already concerned that the loss of so much open moorland below the 300 metre level was reducing the numbers and variety of hill birds, and might seriously limit food and hunting grounds for harriers and other predators, particularly eagles and Buzzards. Ravens, much dependent on sheep carrion, decreased sharply as the forests spread.

  When, at the beginning of May 1965, two cock harriers were seen displaying over seven year old trees near the western end of Area C, and one nest was found shortly afterwards, there seemed no reason why nesting should not soon spread over a large extent of similar-aged forest. This first nest among the trees was a failure, the hen sitting on a clutch of only two eggs till long past the time they were due to hatch. The second and more handsome cock, looking almost as white as a gull against the dark conifers, was often seen over a long valley, apparently well stocked with good nesting sites, until he disappeared at the beginning of June. In 1966, three young were fledged from a nest about 800 metres from the 1965 site. This nest was notable for the discovery of a Crossbill’s head among prey remains—it was identifiable as an adult female of the Continental race, a flock of which had been seen in the vicinit
y shortly before. However, it was soon apparent that the forest-nesting harriers hunted much more over neighbouring moorland (especially the old nesting area, Area A) than in the forest itself. No nests were found in 1967, only a cock being seen at the 1966 nest site, though the number of harriers in the forest continued to increase slightly (see Fig. 10). Poor conditions for hunting in a very cold, wet May, possibly inhibited breeding. Increased nesting in 1968, with three broods in Area C, resulted in the highest annual total of ten fledged young. Two of these, from different nests, were later recovered: one found ‘decapitated’, suggesting the possibility of a fox kill, on moorland 35 kilometres SW, on 21 April 1969; and the other reported ‘found’ only 14 kilometres away in the same direction, probably on farmland, near a small winter roost, on 10 October 1971. Seven, or over 21%, of the first 33 young ringed and fledged were therefore recovered, a remarkably high proportion even for a predator which is killed by man. At least it can be said that all but one had survived long enough to breed. At one of the 1968 nests I found definite evidence of a chick being eaten by its siblings in the nest, though it had probably died first, during the wet weather in July and the consequent poor hunting conditions for its parents. The latest brood, fledged at the end of July, continued to use the nest as a base during the first three weeks of August. By then, the cock had disappeared and the young were flying to the incoming hen to catch prey which she dropped from a height, although they sometimes missed their catches. They had regular feeding places in a big ride near the nest and left many tell-tale remains there. This habit was often seen near other forest nests in later years.

  Young Merlin

  There were now signs of a regular but unequal spacing between nests, of two to three kilometres. In this respect 1969 was a repeat of the previous season. Two nests had small broods and one, at the site first occupied in 1968, was abandoned at a very early stage. This may well have been due to disturbance by forestry work in the vicinity. The behaviour of the cock at this site followed the pattern observed at other sites where early failure or disappearance of a hen occurred. On 31 May he was making conspicuous flights, with some bouts of ‘sky dancing’, over about two square kilometres of forest in the nest area. Soon afterwards he had disappeared.

  Nesting in Area C reached its peak in 1970. Five nests were built, young were reared in four, but broods were again small. At one successful nest a young hen, in her first or second summer, bore a ring. A second pair were nest-building only 800 metres from this nest on 17 May, but in June their nest was found abandoned and contained only fragments of egg shell. The possibility that contamination by toxic chemicals was reducing hatching existed at this nest, and at another where only one chick survived from a clutch of three or more eggs, but unfortunately no eggs were analysed.

  The most surprising nest was in 18 year old forest, where none had been known before. Although most of the surrounding trees looked far too tall and dense for nesting harriers, the birds were able to find a small open patch where the trees remained stunted and bushy from early deer browsing. Such sites are extremely difficult to locate, and the nest would certainly not have been known if a forester had not found it. All the other nests were in the usual areas, where most of the trees were now 10–12 years old. Langley Roberts’ observation of a hen displaying over the site unoccupied since 1962 suggested that this was still attractive for nesting.

  In 1971, only single ringtails were seen at the two more recently occupied sites, and nothing was seen at either in later years. Nor was there any sign of nesting, after 1971, at the oldest site occupied since 1965. Here, in 1971, an old, very pale-eyed hen broke her eggs. She was probably the bird which had had only one chick in 1970. Only the central site continued to be tenanted by a pair in most years, but after a brood had probably been taken by a fox, in 1974, there was no sign of nesting in the following year. At this site, with a remarkable run of closely-sited nests, the same timid, pale-breasted hen was recognised for three years, and when other younger hens succeeded her, they also built within a few metres of previous nests. The cock was not always the same, so it must be presumed that some sites have a special attraction, perhaps increased by the evidence of former nests.

  Very likely, as much of the forest in Area C approached 15 years, harriers were faced with a shortage of suitable nesting places, but the history of Area E casts doubt on this as a full explanation for the decline. Area E was planted in 1959–61. Harriers may have nested there from 1966 but no proof of nesting was obtained before 1971, although much time was devoted to watching the area each season. In 1971 and the following years, single successful nests were recorded, until, in 1971, after two pairs had been seen in April, there were three successful nests apparently attended by a polygynous cock. The locations of all the nests in Area E were concentrated in an area of about two square kilometres of forest, planted in 1961 (see Chapter 14).

  A rather similar history of summer sightings of pairs, or adult males alone, occurred in the forest Area D, from 1966 onwards. Here no nests were ever found—if one excludes nest-building by a cock, in the absence of a mate, on 19 May 1974. The absence of nests could not be explained by the lack of nest sites, as the terrain, and the average age of the trees, was similar in both the other areas. There was no apparent reason why disturbance should have been greater in Area D than elsewhere. The most likely reason for the absence of nesting in Area D can be found in a comparison of the hunting grounds accessible to the three areas. In this respect, Area D differed from the others in having much less open moorland, below 225 metres, within normal hunting range. The implications of this difference are considered in the discussion of hunting ranges and prey, in Chapter 16.

  To some extent comparison can be made between Area D and other more distant forests, such as Areas H and J, where summer sightings were quite frequent in the later years but nesting was rarely proved, in spite of many hours of observation and close liaison with forest rangers who regularly worked the ground. In April 1972, we witnessed intense skydancing by a cock over a 300 metre slope of forest in Area H, possibly stimulated by the presence of another pair not far away. Sometimes, two hens were seen and later, when one was on eggs, the second cock hung over the nest until gently ushered away by the other. This nest, in a remote part of the forest, seemed to us well-placed for success but the chicks were found dead, and a bunch of feathers from the missing hen suggested that she had been killed or involved in a struggle. It was neither the first nor the last time that the mystery of a failed nest could not be solved. Our guess was that word of the nest had reached neighbouring keepers.

  In the last five years, special attention was given to nesting in Area E, where a timid, pale-breasted hen, possibly the same bird which had been in Area C, nested successfully from 1971–74. When the nest was visited she would rise and fly away, circling at a distance of 100 metres or more. We never saw her well enough to note the colour of her eyes. In 1974, the cock was a memorable and beautiful old bird. He was the only male, over the years, to make really low-level attacks on human intruders, sometimes striking with a wing but never with his feet lowered. He also spent much more time than most near and, even, at the nest and was a most assiduous provider of prey. In one period of under four hours he brought prey seven times. When I visited this nest just before the four chicks flew, one of the adults had just brought a fully feathered young Skylark which was still breathing, though probably unconscious from a head wound.

  The harriers in this forest were often visible to passers-by on a public road. Indeed, some food passes took place directly above the road, and the cock regularly crossed it on flights to and from hunting grounds on the adjacent moorland. Not much ‘skydancing’ was seen in spring but, even so, a pair were very conspicuous before the eggs were laid. On 7 April 1975, a day of bitter north-east wind and snow showers, the birds were already together above the previous year’s nest, leaning into the wind on flexed wings, their partly fanned tails as mobile as kites’. A week earlier they had not been
there, and several had still been using the winter roost a few miles away. Then, on the night of the 6 April, the roost was deserted. On the next day this pair were on their breeding territory, the cock even ‘skydancing’ a little, and at dusk they roosted among the trees. I had no proof that they were birds which had been wintering locally, but it seemed very likely, and they may well have arrived on the breeding grounds together.

  In the three seasons, 1973–75, watches in April showed that the first choice of nesting place was abandoned each time. Once, the hen behaved as if she already had eggs, on 19 April, but no broods hatched before early June. Early nests were not abandoned because of any disturbance by us, but the cost of avoiding such disturbance was the lack of proof that eggs were laid. Whether or not eggs were laid, these early desertions were probably directly or indirectly due to very cold spells in May.

  Early in May 1975, a second pair were over the forest, only about a kilometre from the first. The cock of the second pair apparently disappeared soon afterwards and we never, positively, saw more than one cock in this forest throughout the rest of the season. On 29 May, the cock was seen to exchange prey with two hens, one rising for the pass from the known nest; the other receiving the prey on the ground about 800 metres away. Later, I noticed that aerial food passes between the cock and the second hen were always close to the ground, the hen seeming to snatch at the prey. Further watches and, finally, some gruelling searches in hot, fly-infested forest led to the discovery of two more nests. The three nests formed the points of a triangle, about 1,200 × 1,200 × 500 metres. In the absence of colour-marked birds it was impossible to be certain that there was only one cock to the three nests, but in the end there was no reasonable doubt. On 20 June, when we found the third nest, with five fresh eggs, we were surprised on one occasion to see the hen travel about a kilometre from the nest to hunt herself, although at this stage she did not appear to be neglected by the cock, who passed prey to her twice between 10.45 and 17.30. After the young hatched, on 9–10 July, the cock was never seen to bring food to her or her chicks. As described in the next chapter, only one chick survived out of three hatched, and even this might have died if we had not provided extra food for a short period. The earliest nest was the most successful. Five chicks hatched in mid-June and four of them fledged. The second nest produced three young. On 6 July, the cock carried prey towards this nest while the hen was probably feeding the brood with prey which she herself had just brought. The cock hung low over the nest as if about to drop his prey, but flew on with it towards the nest with the largest brood. Owing to an intervening crest of the hill we could not see what ensued but it could hardly be doubted that he took the food there, or passed it to the hen at that nest. We often saw him close enough to judge his plumage colour and he was not the fine old fierce cock of 1974, but a younger bird, probably about three years old.