The Hen Harrier

by Donald Watson

  The spring of 1961 promised well, with two pairs on the old moorland, but a double failure ensued. The presumed old pair made one, or probably two, false starts, nest-building being observed on 17 April very close to the 1960 site. They were rarely seen for most of May until on 30 May the new shepherd, Jimmy Stewart, while on his daily round, raised a hen from a single egg in a nest just below the crest of a heathery ridge a mile away. Meanwhile, the second pair had haunted the flat ground below the 1959 site, built a flimsy nest on an exposed patch of bog myrtle and molinia, much too near the public road, and had two eggs sucked by crows. The eggs may have been abandoned before the crows took them. The failures may have been due to human disturbance, as the shepherds were questioned by strangers determined to find nests early in the season. The pair on the flat also seemed to be unsettled by the Buzzards which had occupied the high ground just above.

  The cock of the new pair was apparently a second summer bird, in half grey plumage. From him I saw the full ‘skydancing’ display for the first time. In late May, after his nest had failed, he travelled around an area about one and a half kilometres square, breaking into this extraordinary loose-winged up and down performance over much of the higher ground. Once, he took prey to a dark-coloured hen, perhaps a newcomer, which would not take the pass. By June, however, the displaying male had disappeared and the only successful nest that summer was the late one which the shepherd had discovered. The cock was probably the same as in previous years, the hen more doubtfully so. She laid seven eggs but, the summer being rather wet, two of the five chicks died. By good fortune the site could be observed from an old sheep stell about 250 metres away, where an ancient spreading larch tree provided cover and much needed shelter.

  This was the fourth successive nest which had Short-eared Owls as near neighbours. The owls were much further advanced than the harriers this time, and I found a feathered young owl away from its nest on 24 June, ten days before the first harrier chick hatched. Jimmy Stewart, the new shepherd, had been recruited as a keen harrier protectionist. He took a path every day only yards above the nest, so I received full reports on the progress of the clutch—eggs were laid every second day—and, later, of hatching. In the later stages of incubation the hen sat tight as the shepherd passed a few metres away. It might seem that the hen was disturbed rather much, as ‘Jock the drainer’ also walked past the nest to and from his solitary work and was duly attacked each time by the hen. Jock was a phlegmatic character and I used to be amused at how little notice he took of these assaults. I doubt if he ever actually looked at the nest.

  The sheep stell was like a seat in the stalls for observing the details of food passes. Sometimes they were nearly overhead and I could see that the hen turned almost onto her back and thrust one of her amazingly long legs upward to grasp the prey. It was soon apparent that the cock had a favourite stance on a green knowe below the nest and here, at hatching time, he dumped the plucked and headless carcasses of three young Meadow Pipits, a young Skylark and a young Whinchat. At this stage he would sometimes carry prey almost to the nest, calling a piercing ‘swee-uk’ when the hen refused to rise, and would then return, still carrying the prey, to his stance, where he called again. Jettisoned carcasses were found to have been ‘gutted’ by the cock, perhaps especially for the liver. If the cock was making a food cache he made no future use of it.

  Around the old stell the tall bracken was alive with small birds - Meadow Pipits, Wheatears, Whinchats and Linnets, especially. Many were young of the year, but Linnets were carrying nesting material in July. Certainly the hen of this harrier pair provided much of the food in the later stages, and she often hunted quite near by. The cock was not seen at all on 11 August when the hen and her three, fledged young were over the crest of the hill.

  The 1962 season looked like being a repeat of 1961, with an old pair back, nesting in the same patch of heather by the shepherd’s path, near the hilltop, and a younger pair building on the flat by the road. The first egg was in the older pair’s nest on 1 May, but when five eggs had been laid, on 12 or 13 May, Jimmy Stewart found the nest ‘pulled out’ and empty. He blamed crows but there was no certain way of telling what happened, though Nick Picozzi suggests that a fox or dog may have been responsible.

  A new nest, with a minimum of material, built 400 metres over the ridge, must have been started immediately, and the two eggs laid in it would have completed another clutch of seven, if the first nest had not been lost. I did not find the second nest till 14 June, when it contained two chicks. Their size showed that there could not have been an interval of more than a day between the loss of the five eggs and continuation of laying. Both chicks fledged.

  Back on the flat by the road, the rather dirty grey male was almost certainly the bird which had displayed so much in 1961. His display flights were spectacular again, including a complete ‘roll-over’ at the top of the climb. On 12 May he was tearing up nest material and carrying it to the patch of bog myrtle used in the previous year. The female followed him into the site, taking more material. This nest-building followed slow-motion flying by the pair together, so low that they almost brushed the tops of the bog myrtle clumps. In this ‘pre-nesting’ ritual their tails were spread like fans. For the second year, this too-obvious site was abandoned, but this time the pair tried again, and on 4 July, four chicks had hatched from a clutch of five in rather sparse heather only a little further from the roadside, but in a much less obvious situation. Here, on 8 July, Langley Roberts reported what appeared to be the first definite case of human destruction. He was confident that the chicks, which he found dead, had been killed by gunshot. The female was missing and had possibly been killed, too. We had earlier suspected that the gap in one of the cock’s wings had been made by a shooter.

  When I recall how Louis and I went forthwith to tell our story to the rather imposing local lady, who had the shooting rights, I am amazed that she listened to us with such patience. I had only seen an empty nest and my story was second-hand. The lady was concerned that harriers were taking grouse, and wished that they would retire to the forest to nest, but she was positive that they had not been destroyed by a keeper in her employment. Ironically, it had been a Buzzard which Louis and I had seen take a grouse chick near the harrier’s nest. A visit to the sheep farmer’s house convinced me that, whatever had happened, it would be naive to pursue my enquiries. Perhaps the absence of any nesting harriers on the old moorland in 1963 was the strongest indication that, as a friend put it, ‘measures were taken’ against them in 1962, just when it had begun to seem that they were set to increase.

  A happier postscript to the year was Langley Roberts’ finding of the first successful nest within the forest boundaries, in Area C. The female at this nest bore a ring and might have been from one of the earlier moorland broods. The nesting place, close to a popular path, was unlike all later forest nests in being on unplantable ground. A ringed female from this brood had had the longest recorded life for the region, when it was found dead on moorland only five miles away on 3 July 1968. A keeper later assured me that a pair reared young on a neighbouring moorland in 1962, and it is possible, also, that a second forest nest was undiscovered.

  The 1963 season followed a memorably hard winter and it is possible that this had an adverse effect on breeding. A male and two ringtails were about the moor in May, but did not settle. On 29 May, I spent 13½ hours watching for flight lines of a cock which I thought might have a nest in the three year old forest (Area E) adjoining the moor, but could not trace him to a nest. The only known nest, that season, was a complete surprise, on a high rushy hillside (Area G), 32 kilometres to the north. First news of this came on 18 May, from a shepherd’s message that a bird ‘like a hoolet with white at the root of the tail’ had risen from eggs. He showed me the nest, which had five eggs, and I was surprised to find that here was another first year male breeding. The shepherd later reported a remarkable clutch of nine eggs, which might have been explained by exceptionally good
food supply in a local vole plague (which also attracted a high number of Short-eared Owls). In June, however, the nest was empty, apparently robbed, and there was no evidence of a repeat laying. So not one young harrier was seen that summer.

  A young Golden Eagle had wintered on the moor, for the first time, in 1961–62, roosting below the Lion’s Head, where it was sometimes seen in pursuit of blue hares. Each year thereafter, eagles were seen more often, as a young pair became established at a nesting site a couple of kilometres from the moorland perimeter. In the 1964 breeding season, the sight of a cock harrier repeatedly diving at a hunting eagle became common, and the possibility that nesting harriers might be seriously unsettled by the eagles was raised.

  That year there were three harrier nests on the moorland, including two clutches of six, so there were hopes of a good crop of chicks. Yet only the third and latest nest, not found till the three chicks were well-grown, was successful. At one of the others the hen sat for at least 52 days on eggs which never hatched (analysis of three eggs for toxic chemicals showed small residues; results are given in Table 16). At the other, the death of the two-week-old brood was never satisfactorily explained, although Dr John Selwyn carried out a post-mortem which showed that they had been well fed. Human predation could not be ruled out. The three nests were evenly spaced, exactly two kilometres apart. Only one cock was seen, and it is fairly certain that this was the first polygynous group of nests. Certainly, the hen with the unhatched eggs was neglected and must have been forced to hunt for herself during incubation. She was an old, yellow-eyed bird—possibly the original hen—and her nest was but 50 metres from the 1960 site, in deep heather by the burn. The hen which lost her brood was young, dark-eyed and intensely aggressive. Indeed, nearly all the hens which nested on the old moorland were bold to a degree, and timid hens were only seen at distant sites or, later, at forest nests.

  In 1964, the extremely open situation, in pure molinia, of the nest in which the young died, emphasised the limitations of the moorland as nesting habitat, since the best cover had been burnt. However, the presence of three nests with, so far, no sign of establishment in the neighbouring forests, underlined the birds’ faithfulness to an old nesting area. This was demonstrated again very clearly in the forest habitat, while apparently more suitable sites remained unoccupied.

  The 1965 season saw the beginning of a continuous history of forest nesting in Area C (see Chapter 12). After the shepherd had found a cock harrier dead, in April, only one pair was on the moorland, but this nest, well hidden in deep molinia, reared five healthy chicks. The hen, from behaviour and plumage, was indistinguishable from the bird which lost her brood in 1964, and the nest was less than a kilometre from that site. The surrounding moorland was the best Golden Plover ground in the district; and the nearest of several pairs of Curlews raised a brood within 100 metres of the harrier nest. Neither species featured as prey at any harrier nest in the locality. The pair of eagles had a chick to feed and the cock harrier regularly chivvied the hunting male eagle. Ever since the eagles had arrived, Buzzards were seen more rarely over the moor. When my wife and I visited the nest to ring the harrier chicks, the attacking hen dropped a young Skylark almost on my head, not the first or last such experience at a nest. A female chick from this brood provided proof of later return to the natal area, when she was found dead on the moor, 400 metres away, on 27 May 1968. The bizarre circumstances of this discovery, described in detail in Scottish Birds (Watson, 1969), are given on page 262.

  In July 1965, I searched for Hen Harriers on moorland (Area B) about 50 kilometres distant and found a pair, but not the nest which they undoubtedly had. The reported words of the head keeper, that a brood of these ‘worst vermin’ had unfortunately escaped him, confirmed that harrier nests would be at risk on this well-stocked grouse moor. The policy was confirmed when we found two pole traps, each with the remains of Kestrels beneath them, set in full view of a road. On an evening of drenching rain the local police helped us gather up the evidence, which I innocently expected would result in a prosecution for illegal trapping. Enquiries were made but, of course, nobody admitted any knowledge of setting the traps. So there was no case. I do not think pole traps were set in that spot again, but there is little doubt that other methods were used to destroy Hen Harriers and, probably, other predatory birds.

  The finding of a ringed female in this area, from the 1964 brood on Moorland A, in July 1966, was an indication that it had been partly colonised by birds from the original nesting grounds. My attempt to obtain details of how this bird died went unanswered and increased my suspicion that it was trapped or shot. From 1968 onwards, R. C. Dickson studied Moorland B and found a very high failure rate in the small number of nests there. Destruction by game keepers was presumed to be the main cause of this.

  Every winter, Hen Harriers were seen hunting moorland area A from time to time. Ringtails were seen more often than adult males. It could only be surmised that some at least were local breeding birds, but when I started to count harriers at winter roosts from 1966 onwards, it became clear that numbers were often too high to be drawn only from the local summer population.

  The 1965 brood was the last that was seen on the old moorland. A pair were back in early April 1966, then disappeared when heavy snow fell in mid-April. They returned later, and I was fortunate in witnessing their courtship and nest-building on 15 May, a day of blue sky and flying clouds. Only the hen ‘skydanced’, switchbacking at no great height, but the pair gave a prolonged display of soaring in unison, rising to a great height with wing-tips almost touching. Copulation took place twice, on the ground, noisily, and the cock led the hen to a possible nest site in moderately long heather, near where there had been successful nests in 1961 and 1962. There was no certainty that the hen was the same as in 1964–65 but she alighted near, and seemed to inspect, old nests of those years. (The existence of old nests is probably a factor in stimulating site selection in the same area. Eddie Balfour later told me that he thought this was true in Orkney.) The hen dropped in to more than one possible nest site and was finally seen carrying nest material. Early in June, however, Jimmy Stewart found two sucked eggs near the nest which she had built and a repeat nest, on the same part of the hill, came to the same end. On 15 May, I had seen the hen being harrassed by a pair of crows but it still seemed surprising that a very mature pair of harriers were apparently unable to protect their eggs from crows. I can only guess that some other disturbing factor, perhaps human, or possibly Golden Eagle or fox, had resulted in much straying from the nest by the hen before incubation had properly begun, and that any watchful crows might have taken their opportunities. An undiscovered nest of some previous year, showing no sign that it had ever contained chicks, was found in the same patch of heather as the first 1966 nest.

  In 1966–67, about one third of the moorland area was acquired, ploughed and planted with conifers by the Forestry Commission. This must have been disturbing to the harriers initially, but its long term importance was to reduce the extent of open ground for hunting. Although in the ensuing years, harriers nesting in neighbouring forests demonstrated the great importance of the moorland as a hunting ground, only once, in 1968, was there any indication that they might nest there again.

  In May 1968, a pair were soaring over the hill top above the old larch tree in the stell, and I saw and heard them battling with the pair of eagles, diving almost to strike them. A week later, John Young and I found the hen dead at this spot, unmarked except for a small wound near the sternum. As I have said, she had been hatched and ringed in the 1965 nest, just down the slope. Did she dive too close to an eagle? I believe she did, and the discovery of an eagle’s pellet beside her body was suggestive of this, though no more. Ian Prestt’s diagnosis that the wound was consistent with having been caused by a talon, and that there was no exit hole for a bullet, added weight to the theory. Our strangely assorted finds also included the plucked wing and partly bitten breast bone of a Snipe, which had perhaps b
een dropped by the harrier, and, 20 metres away, a Red Grouse nest which had been destroyed. Its ten eggs, mostly bitten through and eaten, and the trail of female grouse feathers, including a bitten off wing, pointed to a fox as the predator—a verdict supported by the late Ernest Blezard, who kindly examined all the incidental remains and confirmed that the pellet came from an eagle. It therefore seemed that, by chance, two possibly quite distinct dramas had been enacted at almost the same spot. So, the short history of Hen Harrier nesting on this moorland ended with this violent mystery.

  The risk that might be run by a Hen Harrier diving too close to a Heron is suggested by an incident described by M. K. Hamilton (pers comm). In this a ringtail harrier, circling in soaring flight, was itself circled by a Heron which carried its neck outstretched and bill open. It appeared to be trying to attack the harrier but was far too slow to come within striking distance. The incident occurred in late August and the harrier seemed quite content to continue circling inside the circuit of the Heron for at least two and a half minutes before the latter folded its neck and broke off the attack. No reason for the Heron’s aggression could be suggested but it may be speculated what would have happened if the harrier had reacted boldly, as it might have done in the vicinity of a nest.

  Possible causes of failure and decline of nesting on Moorland A

  In 1962 it seemed that a group of pairs might become established. This was the time when local gamekeepers became most concerned about the possible impact of several pairs of harriers on grouse stocks, and some persecution probably occurred. The lack of nests in 1963 may have been due to this, but an additional factor may have been the severe weather in late winter (the exceptionally large clutch that year on Moorland G coincided with a local vole plague).