NOTES. Micrograms I.O

Transcription

1 Notes Peregrines rearing young Kestrels. On nth April 1963 W. N. Charles and I flushed a Peregrine {Fako peregrinus) from its eyrie in an old Raven (Corvus corax) nest in the Dumfriesshire hills. There were four eggs, one of which we took (under licence) for chemical analysis because the eggs of this pair had been broken in 1962, apparently by the Peregrines themselves, and it was suspected that the female at least was suffering from a sub-lethal dose of toxic chemicals. On 14th June the female Peregrine again flew from the eyrie, which, however, now contained a clutch of four typical eggs of the Kestrel (F. continued

2 BRITISH BIRDS tinnunculus). As proof that they had been laid there by that species, there were in the nest a Kestrel's tail feather and characteristic castings composed of the fur of Short-tailed Field Voles {Microtus agrestis). A search in the litter produced fragments of shell and membrane, apparently from the Peregrine's own eggs. The female Peregrine had presumably destroyed her clutch, as has so often happened during recent years (e.g. Brit. Birds, 51: 23-26), and quit the eyrie. A pair of Kestrels must then have taken over the old Raven nest and later, after their eggs were laid, been dispossessed by the Peregrines which carried on as if nothing had happened. A similar instance of a Peregrine appropriating a clutch of Kestrel eggs was reported by the writer from near Inverness in 1961 {Brit. Birds, 55: ). On 19th July both Peregrines came out calling furiously from the crags as I arrived, and on the nesting ledge were four fully-fledged young Kestrels. All but one had lost the nestling down completely; two took wing and flew quite strongly on my approach, though they soon pitched on the adjacent slope. The two Peregrines meantime kept up a tremendous demonstration, the female now and then stooping quite close to me. On 28th July both Peregrines again flew out when I reached the crags and began calling continuously. One after another, three of the young Kestrels appeared in the air, circling, gliding, diving or winnowing in normal flight. They kept some distance from their disturbed foster-parents and gradually drifted away. After a while the fourth Kestrel appeared and joined the two Peregrines, circling with them and occasionally stooping at one or the other; once it came over to inspect me and called. It was much more inclined than the others to stay with its foster-parents, which quietened down somewhat after it took to the air. The Peregrines showed a strong attachment to the nesting haunt, and when I sat some distance away to watch, they perched on rocks or occasionally circled over instead of drifting away with the Kestrels. At intervals two of the young Kestrels hovered in the proper manner of their kind, so that this instinct remained unimpaired by the strangeness of their upbringing. Incidentally, on this day a pair of adult Kestrels probably the original owners of the eggs were hanging about the Peregrines' alternative crag half a mile away. On 3rd August both Peregrines made the usual din when I reached the top of the crags and all four young Kestrels took to the air together. Again, one of the latter was more inclined than the rest to circle around close to the Peregrines and several times came close to me, adding its own voice to the commotion. When I left, the Peregrines followed me for several hundred yards across the moor, the female calling nearly all the time. 458

3 NOTES Pluckings at and near the eyrie, kindly identified by E. Blezard, showed that the Peregrines had been taking a normal selection of prey. There were the remains of several domestic pigeons {Columba livid), two Skylarks (Alauda arvensis), two Starlings (Sturnus vulgaris) and at least one each of Red Grouse (Lagopus lagopus), Redshank (Tringa totanus), Dunlin (Calidris alpind), Wheatear (Oenanthe oenanthe) and Meadow Pipit (Anthus pratensis). An unusual additional item, however, was a casting composed largely of the fur of a Rabbit (Oryctolagus funiculus), but mixed with bird remains, which proved that the Peregrines had certainly taken the Rabbit themselves. The young Kestrels appeared to have thrived on this rich fare, though they would presumably turn to the usual voles and lesser fry when the time came to fend for themselves. The chemical analysis of the egg was undertaken by the Agricultural Scientific Services of the Department of Agriculture and Fisheries for Scotland, Edinburgh, and I am indebted to N. Morgan and G. Hamilton for the results. The egg contents were examined by gas chromatography and contained the following pesticide residues: Lindane Heptachlor Heptachlor epoxide Dieldrin D.D.E. D.D.T. Totals Micrograms I.O Parts per million O.IO 2.60 O.IO The total content of chlorinated hydrocarbon residues was thus about three parts per million. Such a concentration is probably well below the lethal dose for an adult Peregrine, but its physiological significance is just not known. The results nevertheless prove the contamination of the female bird and give strength to the idea that abnormal behaviour is one of the effects induced by sub-lethal doses of pesticide. In this case there was evidently a conflict between the normal maternal urge and the perversion which leads the bird to destroy its own eggs. There was nothing to show what stage of incubation had been reached by the Peregrine before its eggs were broken, or by the Kestrel before it was evicted. In 1959, another Peregrine in the same area broke its eggs when they were fresh and then produced a repeat clutch after the normal interval. Yet Peregrines which are robbed when incubation is advanced seldom lay again and have not been known to recompense themselves by taking over the eggs of another species. And since nesting Peregrines seldom, if 459

4 BRITISH BIRDS ever, permit Kestrels even to hang about within close distance of their eyrie, they must have completely deserted the breeding place for a time, or the Kestrels would have had no chance to appropriate the site. The abnormality thus went beyond the mere taking over of the eggs of another species. Whatever their earlier behaviour, however, the Peregrines appeared to react to the young Kestrels exactly as though they were their own offspring, and were presumably still feeding them when they had left the nest. D. A. RATCLIFFE Inland passage of Oystercatchers in central Wales. In an article on the migrations of the Oystercatcher (Haematopus ostrakgus) (Brit. Birds, 52: ), D. G. Andrew remarked that the description of this species in The Handbook as an irregular and very scarce visitor on passage inland 'may hold true in other parts of Britain, but in autumn it is both regular and abundant as a passage migrant across south Scotland'. It may therefore be of interest to record that an inland passage of Oystercatchers occurs, probably regularly though only in small numbers, through some of the river valleys of central Wales. The movement may be observed in both spring and autumn, during March-April and late July-August, with one occurrence of three as late as 29th September 1903 (The Birds of Brecknock, 1957, p. 215). However, as in the case of south Scotland, the spring passage is very much smaller and less frequently observed than that of the autumn, though we cannot say if an alternative route is used. The numbers recorded so far have not exceeded six in a group, and usually only one to three have been seen. The habitats selected by the birds for resting or feeding are typical: rivers, pools, lakes and reservoirs. If, as D. G. Andrew stated, much of the migration takes place at night and the migrating parties seldom stay long at the reservoirs, then the actual movement may be larger than it seems. There are also few observers in this part of Wales. Oystercatchers are not the only waders to be seen passing through this area, and preliminary results of a study of the regular though small migration of waders and terns along the inland valleys of the rivers Usk and Wye already indicate a fairly distinct pattern. So far the Oystercatchers have kept fairly close to the main routes. In autumn, they pass down into Radnorshire (and probably Herefordshire), where some may stop at one or other of the reservoirs in the Elan Valley, or at a pool, and hence travel via the Wye Valley as far as the 'central plain' of Breconshire, which they cross southwards to Llangorse Lake. The movement further south is not so clear in this particular case, as some turn up at Tolybont Reservoir in the Brecon Beacons (which has also attracted many other waders and terns), though apparently none has yet been recorded along the more obvious route via the Usk 460

5 NOTES Valley, through Monmouthshire, to the Bristol Channel (The Birds of Monmouthshire, 1963, p. 27). Although recent records greatly outnumber earlier occurrences, it is felt that this is due to even fewer observers in former years, for such older records as are available fit neatly into the present-day pattern. It therefore seems probable that the Oystercatcher has been a fairly regular autumn migrant and an occasional spring migrant through parts of Breconshire and Radnorshire for many years. JOHN GRIFFITHS and GWILYM GRIFFITHS Blue Tit lining and laying in nest of Blackbird. On 20th April 1962, at Newton-le-Willows, Lancashire, I found the nest of a pair of Blackbirds (Turdus merula) some seven feet from the ground in a rhododendron; it contained two eggs. When I next examined the nest, on 12th May, it had been lined at the bottom with hair and feathers and held a single egg of a Blue Tit (Parus caerukus); there was no indication of what had happened to the original eggs. I paid several further visits and then, as no more eggs had been laid and the nest was clearly deserted, I removed the whole structuie for closer examination. I found that the lining added by the Blue Tit was 5 cm. in diameter and at the centre was 9 cm. below the nest rim. The structure gave the impression of having been deepened before the lining was added. F. E. STEPHENSON Blackbirds fostering nestling Bullfinches. At noon on nth June 1963, in his garden near Cranleigh, Surrey, Colin Warner noticed that a pair of Blackbirds (Turdus merula) had begun to brood and feed three nearly fledged young Bullfinches (Pyrrhula pyrrhula) in a nest in a small but thick clump of bamboo, and on the 12th he invited us in to make observations. It is not clear whether the parent Bullfinches had deserted the nest or the Blackbirds had simply taken over, but the female Blackbird regularly brooded the young until at least the evening of the 14th and both she and her mate fed them continuously with small caterpillais and grubs throughout those four days. The female looked somewhat ungainly on the frail nest; she used to sit towards one side of it and it tended to tip slightly as a result of her weight. She would allow us to approach to within a yard and the young Bullfinches could be seen looking out from under her feathers. The adult Bullfinches used to return to an apple tree near-by for a few minutes at approximately hourly intervals and one of them, usually the male, would approach to within a few inches of the brooding Blackbird before flying off calling, but they did not try to chase the fosterers away and the sitting Blackbird showed no reaction to their presence. Both 461

6 BRITISH BIRDS Blackbirds used to leave the nest completely for about two hours every evening, from 7 p.m. to 9 p.m. On the evening of 14th June the three young Bullfinches were still in the nest but looking very alert and ready to fly. On the 15 th one of them was seen in a tree near-by with the female Blackbird perched not far away, but she made no attempt to feed it. Another of the youngsters had apparently come to grief as there were feathers on the ground, and there was no sign of the third. None was seen after the 16th. The young in a Blackbird's nest not far away had apparently been taken by Magpies (Pica pica) within the previous fortnight and we think it possible that it was the adult Blackbirds from this nest which were fostering the young Bullfinches. JOHN and ELIZABETH WELLER Another case of fungus disease affecting a Robin. On 6th March 1963 the body of a male Robin (Erithacus rubecuia) was received at the Veterinary Laboratory of the Ministry of Agriculture, Fisheries and Food, at Lasswade, Midlothian, from Dr. A. Jobbling of Woodstock, Oxfordshire. It had been kept under observation at a bird table for some months as it was beginning to show signs of 'baldness'. It was eventually found dead and was thought to have been killed by a cat. Post-mortem examination showed the bird to be in good bodily condition and the internal findings were consistent.with attack by a predator. Externally, the changes in the skin were indistinguishable from those illustrated and described previously (Brit. Birds, 54: ). The areas of the head and neck and above the right tarsal joint showed a chronic dermatitis manifested by loss of feathers and off-white dry exfoliation and thickening of the skin. Microscopic examination revealed the typical changes associated with favus which, in the domestic fowl, is caused by Trichophyton galiinae. There were numerous resting and vegetative stages of the fungus confined to the horny layer of the skin. No underlying tissue reaction was present. Repeated attempts at isolating the causative organism, both at Lasswade and at two other laboratories, failed and there was unfortunately not enough material for transmission experiments. Nevertheless, the microscopic changes in the skin were sufficiently characteristic to justify a tentative diagnosis of a favus-like condition. ]. W. MA.CDONA.LD Red-eyed Vireos and other American birds in the Isles of Scilly in early October Between the afternoon of 30th September and the early morning of 4th October 1962, single individuals of Lesser 462

7 NOTES Golden Plover (Charadrius dominkus), White-rumped Sandpiper (Calidris fuscicollis) and Least Sandpiper {Calidris minutilld) arrived on St. Agnes, Isles of Stilly. With a huge and remarkably circular depression centred over the middle of the North Atlantic on 29th September, and considering the exhausted state of the first two birds, there can be little doubt that they had all initially been blown off course and then aided in their trans-oceanic flight by gale-force winds from the west. This remarkable procession of Nearctic waders did not, however, do anything to prepare the observers concerned for the last arrivals in this period. During the afternoon of 4th October, R. E. Emmett, I. J. Ferguson-Lees and my wife and I were combing the bulb fields and wooded gardens in the centre of the island when, at about 3.45 p.m. BST, a large warbler-like passerine was seen darting about in a tamarisk. A moment or two later my wife and I got the first clear view, immediately noting a heavy bill, a striped head and greenish upper-parts. This combination of characters prompted me to shout, 'Vireo!'. The other two observers were quickly clear of cover but not before the bird had begun a series of rapid and lengthy flights. Eventually, however, a prolonged watch inside the adjacent parsonage garden gave all four of us excellent views at a few yards in both shadow and sunlight. The bird was then quickly identified, with field reference to Roger Peterson's A Field Guide to the Birds (1947), as a Red-eyed Vireo (Vireo olivaceus), only the second to be recorded in the British Isles and Europe and the first to be seen alive. A full description and sketches were made and even when it was not in view, its progress through the leaf-canopy could be traced by its frequent calls. The note might be written as tchay and, with its pronounced nasal twang, was remarkably like that of a Willow Tit (Varus montanus). The si2e and total length were similar to those of a Great Tit (Parus major) but with a correspondingly short tail and heavy, bloblike bill. Our first impressions were of a fairly bright greenish bird moving boldly through foliage, showing a dark cap, black and white head-stripes recalling a Firecrest (Regulus ignicapillus), and whitish under-parts. The following detailed description was obtained between about 3.45 p.m. and 5.30 p.m. in a series of short views from fifty yards down to a few feet: Upper-parts: crown grey, looking faded or quite bright blue-grey (and even black when feathers raised) according to angle of light; supercilium conspicuous, pure white bordered with lines of black above and below (the lower line passing through the dark eye); rest of upper-parts, including wing-coverts, pale but fairly bright olive-green (greenish in dull light) with a lighter and silvery grey-green panel on inner half-dozen secondaries, recalling the panel of an Icterine Warbler {Hippolais ictmna); primaries and tail-feathers browner 463

8 BRITISH BIRDS green (but tips of latter paler). Under-parts: chin, throat and centre of chest clean off-white; ear-coverts and cheeks washed with olive-green, this extending to sides of chest and flanks; under-tail coverts washed with yellowish-gfeen (appearing yellow in sunlight). Bill dark blackish; legs greyish in sunlight and dark blue-grey in shadow. The actual colour of the eye was not seen on 4th October, but on the next day, with the bird sometimes in more open surroundings, we frequently caught a glint of red from mid-day onwards. During the early afternoon of 5 th October, I. J. Ferguson-Lees and I were again in the parsonage garden when suddenly not one, but two Red-eyed Vireos appeared within a foot of each other in the same bush. The fact that there were two cleared up some variations in the plumage details which we had noted on the 4th and also probably accounted for the vociferous calling which we had all thought unusual for such a bird on its own. The second one differed from the first in the following respects: Generally duller with greyer crown (never showing blue) and less intense black borders to the supercilium. Upper-parts less green and wing panel not so obvious. Under-parts duller white. Eye apparently blackish in all lights and at all angles. For the rest of the 5 th, we were able to study the two birds at varying ranges and in all lights, and concluded that we were looking at one adult and one immature. Both remained fairly secretive, taking cover at any movement, but nevertheless they were watched as they worked their way through the leaves of ivy, elm, pittosporum, apple and other trees and shrubs. They picked insects off foliage, both when perched and in hover-flights, and once one was seen fly-catching. They both flicked their tails frequently and clearly kept in contact by calling; at one time a prolonged duet of tchay, tchay was heard. It seems very probable that both were present on the 4th and we saw them regularly up to the 7th, our last full day on the island. On the 6th we weie joined by G. J. Harris, R. Khan, N. R. Phillips and B. P. Pickess, ail of whom also saw at least one of them during the next few days. They last saw the immature on the 9th and the adult on the 10th, when K. H. Hyatt was also present. Finally, the last-mentioned observer, together with B. S. Milne and F. H. Waters, had a brief view of the immature on the 17th. D. I. M. WALLACE Baltimore Oriole in Sussex. On 5th October 1962, in a fairly dense clump of bushes at Whitbred Hollow, Beachy Head, Sussex, I became aware of a more or less continuous harsh call which was quite unknown to me and which I traced to a bird perched on an elderberry bush some twenty yards away. This bird was about the size of a Starling 464

9 NOTES (Sturnus vulgaris), but its under-parts were of a strikingly brilliant orange, contrasting with a black head, upper back and throat; there was also orange on either side of the black throat-patch, which came down almost to a point, and on the carpal joint; its wings were black with a good deal of white, due to many, perhaps most, of the feathers having white edgings; and its bill was greyish, thick at the base (but coming to a sharp point), somewhat decurved and not quite as long as the head. I had been watching it for three or four minutes when it made a short flight into another bush and disappeared. As it flew I saw that its lower back and rump were also brilliant orange and that its tail was black, with orange at the sides. Owing to the shortness of the flight view, I got no clear impression of the wing-pattern except that it showed a good deal of white. I did not find the bird again though I heard the call for a short time afterwards, now intermingled with a curious whistling which presumably came from the same source. It was, however, seen briefly by R. H. Charlwood on 6th October, about 200 yards from where I had watched it. He described it as 'size about that of a Starling with a conspicuous double white wing-bar; upper back and whole of head and neck black and then this lovely orange rump and breast'. No other details were noted owing to the briefness of the view. There can be no doubt that this was an adult male Baltimore Oriole (Icterus galbula), and R. G. WagstafFe of Liverpool Museums has confirmed that the description fits no other species of the American genus Icterus. The only previous British occurrence to be accepted as genuinely wild was an immature seen and trapped on Lundy, Devon, from 2nd to 9th October 1958 (Brit. Birds, 56: 52-53). D. D. HARBER [We are indebted to M. D. England, Derek Goodwin and R. A. Richardson for the information that a few Baltimore Orioles, perhaps less than a dozen, were imported two or three years ago and several others in the autumn of The possibility of such an origin for the Sussex bird cannot be entirely excluded, therefore, but we have not heard of any escapes and this species often loses its intense orange after a moult in captivity. Moreover, the date of the appearance of this individual agrees closely with that of the Lundy record in 1958, while the first fortnight of October 1962 was a period which brought unprecedented numbers of American passerines out over the Atlantic (Brit. Birds, 56: ) and two or three other species are known to have reached Britain and Ireland at this time. These included the two Red-eyed Vireos (Vireo olivaceus) on St. Agnes, Isles of Scilly (see pages ), and a Rose-breasted Grosbeak (Pheucticus ludovicianus) on Cape Clear Island, Co. Cork (details to be published shortly). We should 465

10 BRITISH BIRDS also draw attention to the conclusions reached by Dr. I. C. T. Nisbet in his paper on 'American passerines in western Europe, ' (Brit. Birds, 56: ). EDS.] Immature Goldfinch trapped by seed head of ragwort. The following observation may be of interest in connection with similar incidents of birds being trapped by the seed heads of plants (Brit. Birds, 51: 276; 54: 246 and 362; and 55: 89-90). On 6th August 1963, on some waste ground at Reading, Berkshire, I found an immature Goldfinch (Carduelis carduelis) with its right foot caught in the seed head of a ragwort (Senecio jacobaed). The bird was hanging head downwards and had apparently been dead for a day or two. Its outer and middle toes had become ensnared in the involucre or circle of modified leaves beneath the flower head. In the ragwort this forms a cup around the under part of the flower and then, after seeding, folds back in the opposite direction around the stem, thus resembling a many-pronged grapnel. Into this the bird's toes had evidently slipped and been trapped, and I had to use considerable force to free the foot. It was surprising that the thin stalk less than a thirty-second of an inch thick had supported the struggling bird. B. G. HAMBLIN 466