The Hen Harrier

by Donald Watson

  This group of nests provided much scope for speculation. Why did the original second pair fail to nest? There may have been a dispute between the two cocks, whose nests might have been only about a kilometre apart, which was closer than any two pairs in the region which had nested successfully. Did the hen of this pair become the second mate of the breeding cock? The hen of the third nest was probably a new arrival in late May. Her iris colour, seen from the hide later, showed her to be young, possibly only a year old. Had she tried and failed to find a cock elsewhere? What was the particular, lasting attraction of this small patch of 14 year old forest, which a casual glance would have dismissed as already far too closed-up for harrier nesting? It was forest where Wood Pigeons were already well established and Short-eared Owls had almost disappeared. It could hardly have been simply the magnetism of former, successful breeding sites. Strong as this may be, it could not be effective without the continuing proximity of good hunting grounds. Again and again the hunting flight lines of forest-nesting harriers demonstrated the importance of adjacent moorland (see Chapter 16). Within five years this forest would surely cease to have nesting sites at all.* Would there still be a chance, then, that a pair or two would return to nest in their favourite hunting grounds on the moorland, where we had found the first nest in 1959? In the next five years that moorland might also be planted with a new crop of trees which could provide nesting sites for harriers only at the cost of eliminating their main hunting grounds. Even if the area remains open, it is doubtful if it now has sufficient growth of heather for good nesting sites.

  Summary of 1976 breeding season

  Two pairs nested successfully in the forest Area E, rearing three and four young respectively; four had hatched at the nest where three fledged. The male at each nest was in grey plumage. A first-summer brown male was also in the area, accompanying a female in late March, and there were probably three, or possibly more, grey males present in early April. A grey male was seen during the summer in the forest Area C but it is doubtful if nesting occurred there. It is fairly certain that nesting did not occur in Area D. Birds nesting in Area E again regularly hunted the neighbouring moorlands, including Area A.

  One pair bred successfully on Moorland Area B. Five eggs were laid, three young hatched and two fledged. A second pair had a nest with four eggs which disappeared before hatching, and a third pair built a nest but apparently no eggs were laid. A fourth pair was present in the area but were not proved to nest. The second pair built a second nest (no eggs seen) only two feet from where the third pair had built and abandoned their nest. (Information on Moorland Area B from R. C. Dickson.)

  No data for 1976 has been included in the Tables 10–15 but the above summary gives a further indication of greater nesting success at nests in forest than on moorland in the study areas of south-west Scotland.

  * In 1975 I found a nest with six young in Kintyre in very young forest with almost no concealment by surrounding vegetation; there was an abundance of food (voles) to be found in the vicinity.

  * In July 1975, Richard Mearns and I came upon an old, previously unknown nest within 100 metres of the nest with three chicks. No sign of food carrying had been seen there in previous years but, in 1974, a second cock and hen had occasionally been seen in the vicinity. This nest may have dated back more than a year. We could only conclude that there had probably been a second nest in this forest before 1975. I doubt if we would have missed any fledged broods but this may not have been the only nest which escaped us, owing to the density of the tree cover and the undulating character of the ground.

  CHAPTER THIRTEEN

  Watch from a Hide

  When we visited all three nests in the 1975 group, on 9 July, the possibility of watching one of them from a hide was in our minds. I had long resisted the temptation, for a number of reasons. Hen Harriers were still scarce nesting birds in the district and I knew it was no use pretending that a hide, to be used for photography, close-up observation and sketching, would be practical in the jungle of 3–6 metre conifers and waist-high heather without some disturbance and the tying back of vegetation to permit clear vision. The very late nest had two newly hatched chicks and two unhatched eggs so, if all went well, there would be time for the bird to become accustomed to the hide before anyone need occupy it. For at least the next two-and-a-half weeks the female would be likely to spend much time at this nest, feeding and brooding the chicks. This was the only nest of the three which Jim Young considered possible for photography as the other two were far too enclosed by trees. He was still pondering the question when we parted that night, after an evening in which flies and midges had been relentless. Next day he had decided that it was worth a try from a photographer’s point of view. We had the necessary licences, and permission from the Forest authorities, and it seemed to me that with two good broods well on their way to fledging and with so much to learn from close-up watches at this third nest, the case for using a hide was as strong as it was ever likely to be.

  Our objectives, and the limitations of observing from a hide in contrast to watching from a distance in the open air, may need explanation. Apart from photography, which was not my concern, there was obviously the opportunity for making close-up sketches, particularly of the female as she fed or brooded the chicks. Even when she was not present, the behaviour and attitudes of the chicks provided a range of subjects for drawing which could never be attained by my usual visits to nests, when the chicks always reacted defensively to a human presence.

  The nest was some six metres from the hide, so it was just possible to focus binoculars on it and we would be able to note details, such as the state of moult and iris colour of the female, difficult to obtain even when a bold bird is flying close overhead. More importantly, there was a good prospect of identifying most of the prey brought in and the amount provided for the chicks during each watch. Further, the hide could reveal precisely at what stage of development the chicks begin to tear up prey for themselves. These and other details of activity in the nest could only be learned from a hide, and there was also the exciting possibility that the cock might pay the occasional visit. I very much wanted a close-up view of him, both as a model for drawings and to clarify my impressions of his plumage detail and likely age, but I was doubtful whether he was still in attendance at this nest and, in fact, he never came to it during our watches. Here, one of the limitations of hide watching, especially in dense tree cover, must be noted. Occasionally, the female could be heard giving the food call as she flew overhead and the most likely explanation would have been that the cock was approaching with prey, but from the confinement of the hide it was never possible to be sure. I was inclined to believe that although she may sometimes have seen him with prey, she never received any from him after the young were very small. Distant watches, at any rate, provided no evidence that she did. The basic limitation of hide watching is, of course, the very restricted field of view but it can also be something of an endurance test when cramp sets in or the feeling of claustrophobia becomes strong.

  Each time the hide was occupied, the watcher or photographer was ‘put in’ by a companion who would then be seen by the bird (if present) to leave the vicinity. At first this worked admirably but later, when she needed to do less brooding, she sometimes observed our approach from a distance and followed us to the nest, calling in alarm, and did not lose her suspicion until an hour or so after one of us had left. If she knew that only one of us had gone, and that the other remained, it seemed that time erased the knowledge. Unable to detect any visible sign of man in the hide she had no lasting distrust of it.

  The hide was set up by Jim and Brian Turner, on 12 July, and moved forward into its final position the next day, after we had seen from a distance that the female had accepted it. Jim took the first watch on 17 July, photographing and observing from 11.30 to 17.30. Three chicks had hatched by 12 July but the smallest was dead on the fifteenth. There were several wet days at this period and we concluded that the female, w
ith little or no food supply from the only cock in the area, was probably being forced to leave the chicks too long unbrooded. Clearly, we wished to minimise the risks of total nest failure so we provided a few extra rations—three sparrows were left at the nest on 13 and 15 July, and were apparently eaten. On 17 July, Jim left a young rat and a young Sandpiper found killed on the road. The latter was removed by the female (and possibly eaten away from the nest) but she fed the chicks and herself on the rat for about 40 minutes that morning, then took away the remains. In the following 4½ hours the only prey caught and fed to the young was a Snipe which was either an adult or a well-grown young bird. My first day in the hide was 19 July, from 11.40 till 18.00 hours. Settled alone, tense and anticipatory but hardly comfortable, I felt totally detached from the world at large. Apart from the all important patch of ground where the harrier’s nest was untidily framed by rank heather, a clump of purple moor grass and the pendulous branches of surrounding spruce and pine, I could see only chinks of grey sky through the slits in the hide, but my awareness of sounds was heightened. The wind rose and fell through the forest like a far away sea on a pebbly shore. Raindrops pattered the canvas over my head. A Wren whirred inches from the hide, like a distant motor bike.

  After only half an hour, the swoosh of wings announced the female harrier’s arrival at the nest. It was her owl-cat face which continually riveted my attention. Her deep-set dark amber eyes were offset by rippling white eyebrows and cheeks, the latter contrasting sharply with her russet brown ear coverts, bordered by the wavy fretted pattern of the neck ruff. It was hard to accept that the intensity of her frontal gaze could not penetrate the hide. She looked big, rangy and powerful; incongruous in the confines of her small nesting space so closely surrounded by trees much taller than a man. Obviously at such a site she must rely a great deal on hearing to sense the approach of danger. I quickly scanned her legs for a ring but there was none. Her dark irides marked her as a youngish bird, probably one or two years old, very likely breeding for the first time. Possibly this had some bearing on the lateness of her nesting. When she settled to brood, with the chicks snugly tucked beneath her, her head and neck looked particularly broad and owlish.

  She covered the chicks without a break for an hour and a quarter, while rain fell spasmodically. Then she walked stiffly to the edge of the nest and took off. Surprisingly, she returned in five minutes with a well plucked carcase of a fairly large bird, which she may have found, caught and plucked in that short time; although it might have been killed and plucked earlier, left and retrieved. I now had a problem of identification. I could see no recognisable feathers and must decide what species it was from the legs alone. It was obviously a game bird. There seemed to be little if any feathering on the toes, but it is one thing to detect, in the hand, those sparse bristly feathers on the toes, which separate the young of Red Grouse from Black Grouse, and quite another when the carcase is six metres away, spreadeagled beneath the crushing grip of a harrier’s talons. I was fearful that movement of my head or hands might show through the slit in the hide. For ten minutes the female fed the chicks small gobs of meat, offering them with a gentle half-turn of her lowered head. Swiftly though the black hook of her bill tore at the flesh, her head moved slowly, even cautiously, in the act of feeding the young chicks. She swallowed larger hunks of meat and bone herself. After ten minutes she lifted the partly eaten carcase in her bill and flew off above the trees. I was fairly sure that the kill was a sizeable young Red Grouse but it was not going to be easy to identify every item of prey whenever it was brought fully plucked.

  I noted that the larger of the two chicks was quicker to grab the food, although sometimes the hen deliberately fed the smaller chick. Henning Weis, in his pioneer study from hides, found that Montagu’s Harriers similarly shared out the food, but Marsh Harriers did not, with consequent, frequent mortality of weaker chicks.

  When the female was absent the chicks’ most energetic task was to ensure nest sanitation. These performances were amusing and possibly hazardous, as the chicks were punctilious in heaving themselves backwards to the extreme edge of the nest to defecate, and if they had over-balanced they would not easily have climbed back over what had become quite a stockade of sticks, this particular nest having been well built-up. I soon learned that even at this stage the hen was frequently bringing new material, sometimes quite large branches of old heather, and she seemed to be trying to build a screen on the more open side, facing the hide. During the early afternoon, light rain fell persistently and the chicks were brooded continuously for forty minutes. When covering the chicks the female dozed briefly although she was generally very alert and snapped at passing flies. She would turn her head swiftly in response to the sounds and movements of small birds in the trees near by, but she did not react at all to low-flying jet aircraft.

  At 14.45 the sun came out and the female left, her barred tail flashing buff, white and brown as she made an almost vertical take-off. She was back in 16 minutes, again with a large plucked prey. This time there was no mistaking the long, bare, greyish legs of Pheasant—a well-grown poult, it seemed, from its size and the few unplucked wing feathers. I had not personally seen Pheasant as prey at a nest before but we knew there were broods in the forest rides not far distant. Evidently the harrier had found one of these because she brought another young Pheasant at 16.35, having been away for 26 minutes; and yet another was being carried towards the nest as I was making my departure at 18.20. This time she had been away for 75 minutes. When I saw her overhead with the prey I thought I had never seen a harrier carrying such a large burden before. Had she not dropped it in panic on sighting me, I might have guessed it was an old grouse from the reddish appearance of some of the feathers, but examination of the body proved these to be the tibial feathering of a young cock Pheasant.

  So, my first day’s hide watching at this nest would have given no comfort to a game preserver. He would certainly not have given the harrier a second chance, but we were to learn that on other days quite different prey was brought. The details of all the prey at this nest are given in Table 9.

  On some days, fledgling passerines (chiefly Meadow Pipit and Skylark) were the sole prey and, once, the female brought two fledglings together. The occurrence of Wood Pigeon, including a squab, was notable. Shortly before Louis saw a fledged young Wood Pigeon brought to the nest, I had watched the female harrier hunting low along a ride between tall conifers where she had doubtless caught it. When the nestling Wood Pigeon was brought, I was at a loss to identify it at first as it was just a squashy bundle, covered with whitish straw-coloured fluff—no need for her to pluck this one. Only the head was diagnostic—the curiously long, almost duck-like bill, with the dark, naked patch extending to the eye. She immediately fed most of the skull contents and the eyes to the chick so I had very little time to make the identification. A quick sketch of the bill and head shape provided useful confirmation, later. I never saw any sign of the legs, and concluded that she may have eaten them before carrying the body to the nest. She was probably in the habit of lightening her larger prey burdens by consuming parts of them herself before bringing them in.

  Other observers have remarked on how clean a Hen Harrier’s nest is kept until the young are nearly fledged, and the hide watches showed that the female always removed the remains of prey. After she had fed the young, she sometimes consumed whole legs of birds herself, in the nest. Once it took her half a minute to gulp down a grouse leg. She made a grotesque picture as she strained and waggled her neck with the horny toes of the grouse still protruding from her gape. Yet very little sign of such large items appears in regurgitated pellets of harriers. On 31 July, it was a little surprising to see a Wood Pigeon carcase taken away and brought back for further feeding twice in the afternoon. Nick Picozzi confirms that prey which is removed is sometimes picked up later, as Jeffrey Watson has recorded for Merlins, and Dick Orton for Peregrines.

  On 23 July, when Jim was in the hide, he witnessed the d
eath of one of the two chicks. This was both a great disappointment to us and a surprise, as the weather had been fine, though cool, and both chicks had fed well. Seven passerine fledglings had been brought to the nest between 10.45 and 16.55, at which time the chick lay flat in the nest and showed no further sign of life. Photographs taken by Jim confirmed that it was the smaller chick which died and I had certainly noticed, earlier, that it was more backward at feeding times. A post mortem might have been interesting, but when Jim left that night he thought it possible that a spark of life remained, so he left the chick in the nest. However, it had been removed or eaten by 25 July. The earlier casualty had disappeared, likewise, two days after death.