Notes Prolonged aerial encounters between Hen Harrier and Goshawk On 17th February 1980, I observed a 'ringtail' (female/immature) Hen Harrier Circus cyaneus flying low over a Yorkshire moorland. I watched it for several minutes, after which it was joined by a male Goshawk Accipiter gentilis. For the next ten minutes, the hawk mobbed the harrier almost incessantly, although for the most part the latter paid little attention. The two raptors were subsequently joined by a second ringtail Hen Harrier, and the Goshawk then divided his attacks between the two; when all three were lost below the horizon, 21 minutes had elapsed since the initial encounter and about 12 attacks had been made during this period. Throughout, the hawk used two basic methods of attack, each evoking a different response; both methods were employed with about equal frequency. The first strategy involved tne Goshawk initially gaining height rapidly to a point 5-10 m above the harrier, and then stooping vertically on to it; the harrier's reaction to this was the same on each occasion: it 'side-stepped' at the last instant and contact was avoided. The second mode of attack provoked a more positive reaction. The hawk would fly strongly upwind of the harrier, and then turn and fly at high speed downwind; when just past (i.e. behind) the harrier, it would turn through 180 degrees, almost on the spot, and attack the harrier from behind. These latter encounters invariably resulted in the two raptors tumbling together in mid-air, wings flapping violently and occasionally the feet of one or both being extended, aldiough talon-locking did not occur on any occasion; these conflicts were typically short-lived, mostly less than five seconds in duration. When both harriers were present, the one not under attack seemed oblivious of the presence of the two other raptors. On no occasion did the harriers consort together to counter-attack the Goshawk.

continued...

448 Notes 449 It is not uncommon for one raptor species to mob another, but such incidents rarely last for more than a few minutes outside the breeding season, as they are presumably wasteful in terms of energy. The above observations seem unusual in both the duration of the encounter and the ferocity which the Goshawk sustained throughout its attack. DAVID S. MARSHALL 28E Ferrier Crescent, Aberdeen AB22QH

One Sparrowhawk killing another In April 1979, on the banks of the River Brue, Somerset, I observed two immature male Sparrowhawks Accipiter nisus (in brown plumage) fighting so vehemently that they seemed likely to fall off their ledge into the water at any moment. An apparently adult female had very shortly before flown swiftly from the scene. For six or seven minutes, the two males fought, until one appeared to be gaining the mastery and eventually got the other down on his back, still fighting, and held him down, with wings outstretched as if mantling prey. There was much squealing, presumably from the losing hawk, whose struggles became more feeble. The victor started to pluck the other; shortly, a piece of flesh came away with a bunch of feathers, which was swallowed; the hawk stopped plucking and remained crouched over his victim, glaring. When the loser appeared to be dead, the victor tried to fly away, but the dead hawk's talons locked in his leg or lower body caused him to make four or five attempts before he succeeded and flew about 50m to a tree. I picked up the dead raptor and could see no injury on it except for the part of the crop torn out during plucking; one can only suppose that it was killed by the sheer strength of the victor's grip. The nearest neighbouring pair of Sparrowhawks was about 3.2km away. HAMILTON RAMSAY The Old Rectory, Alford, Castle Cary, Somerset BA7 7P.X

Dr Ian Newton has commented as follows: 'During our work in south Scotland, among about 10,000 prey remains examined in 1971-80, we found six male Sparrowhawks (two adults, two yearlings, two fledglings) in items from the breeding season and three juvenile Sparrowhawks in those Irom the autumn. Whether these resulted from routine predation or from fights (the victor eating the loser) we could not say, but the fledglings were almost certainly the result of predation as they had been ringed in a neighbouring nest the previous week. We also found many instances of Sparrowhawks eating their own young alter the latter had died from some other cause.' EDS

Insect food of Hobby I n their paper on Hobbies Falco subbuteo (Brit. Birds 73: 1175-295), D. Fiuczynski and D. Nethersole- Thompson listed various insect prey taken by this species, but the only moth specifically mentioned was the fox moth Macrothylacia rubi. In the Derbyshire Peak District, where Hobbies are not known to breed, their presence is firmly associated with flights ol northern eggars Lasiocampa quercus callunae. This moth has a two-year life cycle: in Derbyshire and South Yorkshire, the adults, which fly from late June to early August, occur predominantly in odd-numbered years, their caterpillars usually being found only in even-numbered years; this pattern is discernible even as far back as the nineteenth century' (F. Harrison in litt.). Hobbies were recorded on the Derbyshire moors in 1975, 1977, 1978 and 1979; in 1978 one flew over in September, whereas prac- 450 Notes tically all the other records were of individuals catching moths between late June and August. In both July 1977 and July 1979, four Hobbies were seen on Beeley Moor, which is considered a particularly favoured area for Lepidoptera (F. Harrison in litt.); they were seen by scores of observers and their food was almost exclusively northern eggars, which were flying around the heather Calluna vulgaris in great numbers. It is interesting that, in 1980, Beeley Moor was visited by relatively large numbers of Cuckoos Cuculus canorus feeding on the northern eggar larvae; on 3rd July, I saw 14 Cuckoos, of which 11 were in only about 4 ha of heather moor. For their comments and helpful discussion, I am grateful to F. Harrison, entomological recorder for Derbyshire; S. Jackson, G. Sellors, K. Smith, D. Sneap, P. Shooter, M. F. Stoyle and M. E. Taylor. R. A. FROST 66 St Lawrence Road, North Wingfield, Chesterfield, Derbyshire S42 5LL

BWP vol. 2 lists oak eggar, fox moth and emperor moth Saturnia pavonia among insect prey taken by Hobbies in England. EDS

Winter behaviour of Water Rails Bernard King's note (Brit. Birds 73: 33-35) reminded me of the following. On 6th January 1979, at Herriotts Bridge, Chew Valley Lake, Avon, I studied four Water Rails Rallus aquaticus closely. They were feeding beside a stream, having been forced out of reedbeds by the extreme frozen conditions. On one occasion, two met at the water's edge, and both immediately adopted the threat-posture, facing

Figs. 1 & 2. Water Rails Rallus aquaticus, Avon, January 1979: left, 'pear-shaped' threat posture, revealing flank-barring, with bird leaning back with neck retracted; right, 'mantling' posture of dominant bird in aggressive contact, attempting to push other bird under water by grasping crown feathers (traced by R. A. Hume from pencil sketches by A. G. Duff) each other with stiffened necks drawn back and bills slightly opened and directed towards the other; their flank feathers were splayed outwards, revealing the barring, and making the rails look curiously pear-shaped (fig. 1). A fight then ensued in which each buffeted the other from the front and faced the other with kicking feet and flapping wings (this seems to have been the counterpart of the typical fight between Coots Fulica atra, although Notes 451 it took place on land). One rail managed to get the upper hand, grasping the crown and nape feathers of the other in its bill tip. ending up on top of it and facing the same way. The former's wings were held open, 'mantling' the by-then cowering rail underneath (fig. 2); still grasping the other's crown feathers, it then forcibly pulled its adversary to the water's edge, attempting unsuccessfully to submerge the latter's head. The losing rail broke free and retreated into the reeds, closely pursued by the victor. Aggressive contact lasted about two minutes, during which there was much 'sharming' and squealing, although it was difficult sometimes to tell whether alarm notes were included. A. G. DUFF I Alder Walk, Frome, Somerset BAH 2SN

One Moorhen killing and eating another On 25th March 1980, from the hide at Abberton Reservoir, Essex, I saw a Great Black-backed Gull Lams marinus land on the water beside a Moorhen Gallinula chloropus and attack it. The gull picked up the Moorhen by the neck and tried, without success, to fly off with it. It then lost interest, and the Moorhen swam towards a raft anchored opposite the hide. A second Moorhen left the raft and swam to meet the first. It jumped on it, turning it over, and held it under the water until it had drowned; the victim offered little resistance. The attacker began to peck at and eat the dead Moorhen, continuing to do so until my companion and I left some 15 minutes later. J. M. CAWSTON / Severn Road, Ipswich, Suffolk IP30PZ

N. A. Wood has commented as follows: 'The gull's action is perhaps the most strange, unless the Moorhen was already either quite severely injured or in a diseased state: a healthy Moorhen is a very agile bird. The Moorhen's subsequent encounter with a second Moorhen tends to suggest that it was not healthy or uninjured: assuming that it was not paired to the second Moorhen, in normal circumstances it would have either retreated from the oncoming bird or, on meeting it, performed 'Mutual-retreat display' (Brit. Birds 67: 104-115; BWP 2). Actual combat takes place only when one Moorhen challenges over territory/boundary ownership, and is hardly likely under the circumstances described. The act of cannibalism seems quite in order, as Moorhens have been recorded taking various carrion: dead sheep [Orn. Mitt. 30: 175-177), a gull (Brit. Birds 58:509), fish (Gerfaut 39: 195-198; Om. Mitt. 18: 123; Charadrius 5: 146); a Moorhen has also been reported killing and eating a small bird captured in a mistnet (Aves9: 138).' EDS

Cranes in Kent in October 1982 At the end of October 1982, a large influx of Cranes Grus grus occurred in Kent, mainly in the Romney Marsh and Dungeness area. The first were two at Walland, Romney Marsh, at dusk on 27th, but these may not have been associated with the main influx, which occurred on 30th, when several flocks were seen during the day. As the flocks were seen at different times, it is impossible to say with certainty how many individuals were involved in total on 30th, but 114 is the maximum. The largest number seen simultaneously was 73, in two flocks, at dusk over the Dungeness RSPB reserve. On 31 st, flocks of 18, ten and five were at Folkestone, Dungeness, and Sandwich Bay, respectively. On 1st November, a flock of 26 was seen at Fairfield, Romney Marsh. All were seen only in flight, except for 17 on the Isle of Sheppey, which were regularly observed feeding from 10th November until they left at 12.30 GMT on 13th; 452 Notes Table 1. Flocks of Cranes Grusgrus in Kent during 27th October to 31st November 1982 Where the same birds were involved, records are bracketed

Time Locality Date Flock size GMT (all Kent)

27.10.82 2 15.40 Walland 30.10.82 2 09.30 Dungeness* 14 10.00-13.00 Dungeness* 17 11.30 Dungeness 8 14.30 Dungeness* 33 \ | Dungeness 16.30-17.00 40 J I Dungeness* 31.10.82 10 09.00 Hamstreet I 9& 1 09.30 Dungeness) 5 10.00 Sandwich Bay 18 11.00 Folkestone 1.11.82 26 — Fairfield 8.11.82 •1 — Sheppey 10-13.11.82 17 — Sheppey 1 13.11.82 17 14.00 Dungeness I

•Details not yet submitted to Rarities Committee these 17 were seen later that day, flying over Dungeness at 14.00 GMT. All observations during the period are listed in table 1. About 170 would be a reasonable estimate of the minimum number of individuals involved in the influx during 27th October to 13th November, with about 192 as the possible maximum. The arrival of the Cranes was undoubtedly related to a period of mainly light (up to force 4) variable northeasterly to southeasterly winds, with mist and drizzle over eastern Europe, the southern North Sea and southeast England during 27th-31st October. These conditions were identical to those during 30th-31st October 1963, when the previous large influx of about 500 Cranes occurred, mainly in Sussex {Brit. Birds 57: 502-508). Although fewer were involved in 1982 than in 1963, there were simul­ taneous reports of unusually large numbers on the western Continental seaboard, mainly in the Netherlands and northwest France. I thank the many observers involved with these records, especially T. E. Bowley, R. K. Coles, N. R. Da vies, S. W. Gale and P.J. Makepeace. SEAN MCMINN Dungeness Bird Observatory, 11RNSSS Cottages, Dungeness, Romney Marsh, Kent

Lapwings robbing Golden Plovers On 28th January 1980, about 150 Golden Plovers Pluvialis apricaria were feeding on a grassy field near Seaton Ross, North Humberside. Scattered among them were 22 Black-headed Gulls Larus ridibundus and three Lapwings Vanellus vanellus. Not only the gulls, but also the Lapwings continuously stole food from the Golden Plovers. Like the gulls, they watched their cousins intently and seemed able to sense imminent prey-capture by the latter. The Lapwing closest to me charged plovers four times in ten minutes and picked up something on two occasions. I suspect that the whole hectic episode stemmed from an unusu­ ally prolific food source and the fact that the markedly efficient predation of Notes 453 this by the Golden Plovers allowed the other two species high odds of successful theft. D. I. M. WALLACE 68 Selby Road, Holme on Spalding Moor, by York Y04 4EU

Crab-eating technique of Curlew On 16th July 1979, in the River Bann estuary near Coleraine, Co. Londonderry, I watched a Curlew Numenius arquata foraging among seaweed-covered rocks for about four minutes, during which time it caught two crabs. In both instances, it carried the crab in the tip of its bill to exposed mud away from the water, where it transferred the prey to the base of its bill and deftly mandibulated it so that the legs and claws were broken off in quick succession; when all the limbs had been removed, it swallowed the body whole, then picked up the limbs one by one and ate them. The whole sequence from capture to completion of consump­ tion took only about 20 seconds. After eating all ten limbs of the first crab, the Curlew returned to the rocks and caught another. The Handbook lists small crabs among food items eaten by Curlews, but the only description of the methods of dealing with prey is 'shifting it without effort from tip of bill to gullet with slight jerking motion of head'. While this simple movement may be sufficient to ingest more manageable prey items, crabs obviously require more attention. D-J- RADFORD 4 High Ridge, Alton, Hampshire

Although crabs are a well-known prey of Curlews, the method of dealing with them does not appear to be well documented. We have, however, published an excellent colour photograph of the capture and a description by the photographer, Keri Williams, of how the Curlew removed the crab's legs before swallowing the body (Brit. Birds 72: 226, plate 107). EDS

Great Skua killing adult Herring Gull On 15th November 1977, after four days of severe northwest gales, heavy seabird passage was still taking place off St Ives, Cornwall. Some Great Skuas Stercorarius skua remained to hunt in the bay for long periods. A number of gulls Lams were feeding at the sewer outlet, mostly by swooping down to the water to pick up emerging morsels. A Great Skua flew in from the open sea at a height of about 5 m, towards the gulls; when over them, it dived swiftly onto an adult Herring Gull L. argentatus, pinning it to the water and delivering heavy blows to its head and neck with its bill. The gull, apparently taken completely by surprise, offered little resistance: it was forced lower and lower into the sea, and within about five minutes the skua was perched on its inert corpse, balancing with half-open wings as both drifted across the bay. Half an hour later, the gull's half-eaten remains were washed back by the tide, the skua having taken mainly the breast and entrails. D. M. NORMAN Hazelmere, 50 Shirbum Road, Torquay, Devon

Instances of adult Herring Gulls forming part of the diet of Great Skuas at North Atlantic breeding localities were noted by Dr R. W. Furness (Ibis 121: 86-92), but D. M. Norman's observation adds detail of the method used by the skua. EDS

Herring Gull locating food with feet On 7th June 1980, I watched an adult Herring Gull Lams argentatus foraging at low tide at Sheep Haven, near Dunfanaghy, Co. Donegal. Much of the sandy bottom of the inlet was 454 Notes exposed, and one small channel carried most of the water flowing into the sea. The gull flew to the edge of the channel and walked into the water. It sat on the water, facing into the current, and paddled with its feet for periods of about ten seconds, these alternating with rest periods of a few seconds during which it slowly drifted back part of the way. This sequence of paddling and resting was repeated frequently during a period lasting 10-15 minutes, during which time the gull had progressed about 10 m up the channel and captured five crabs. The paddling action was obviously more vigorous than that required merely to swim up the channel, and created some turbulence. When paddling, the gull looked downwards, and, on spying its prey, upended in the manner of a Mallard Anas platyrhynchos so that its head and upper body were immersed; all five crabs were caught in fairly quick succession. The following morning, a Herring Gull (possibly the same individual) behaved similarly in the same channel: in five minutes, it caught and ate two small crabs. The Handbook does not mention Herring Gulls making foot movements of this kind to find prey. D.J. RADFORD 4 High Ridge, Alton, Hampshire

Dark breast-side marks on adult Whiskered Terns On 24th March 1982, we watched at least six adult winter Whiskered Terns Chlidonias hybridus at Lake Tiberias in Israel. Three showed variable dark marks on the breast-sides, which took the form of a 'comma' on two birds but a fairly large round spot on the third; the others showed no such marks. This plumage feature is known to occur on juveniles and first-winter individuals at least until December, but our observations show that it can also be shown by adults in winter plumage. IAN HODGSON, TREVOR WYATT and TERRY WYATT 73 Middle Deal Road, Deal, Kent CT14 9RG

Little Auks scavenging at trawler Philip Watson (Brit. Birds 74: 82-90) mentioned Razorbills Aha torda and Guillemots Uria aalge being seen in circumstances suggesting that they were scavenging at trawlers. On a few occasions during 12th-16th November 1959,1 saw Little Auks Alle alle pick up waste fragments from alongside a research trawler fishing on the Nova Scotian Shelf (43°N, 63°W): in nearly calm weather, with the vessel stopped, singles fed without diving where a trickle of washdown water was carrying waste out of a scupper. One of the main fish in the catches was redfish Sebastes mentella, a species that often feeds on macroplanktonic crustaceans such as euphausiids, hyperiid amphipods and the larger cope- pods. Expansion of swimbladders often causes stomach eversion in redfish, so the washdown water would have contained items similar to the Little Auk's normal food. E. I. S. REES Carregy Gad, Llanjairpwll, Gwynedd

House Martins attempting copulation in flight In the late 1970s, on warm days during mid to late September, in northeast Hampshire, I observed House Martins Delichon urbica apparently copulating, or attempt- Notes 455 ing to copulate in the air. This was preceded by a 'courtship' display in which a group of two or three martins indulged in a short aerial display, often with arched wings held in a V-shape and a short downward spiral, one slip-streaming another. The successful individuals usually paired off, and one alighted on the back of the other, the two falling through the air for a metre or so before separating. In September 1980, I frequently witnessed this alighting of one upon another. Whether the martins were juveniles or adults I do not know, since the behaviour often occurred towards evening, when plumage details are obscured by failing light. I have often watched House Martins in spring, but have not seen anything approaching this behaviour; in fact, the martins almost immediately commence refurbishing old nests, and I have assumed that mating takes place on the completed nest. E. M. RAYNOR Priors Mead, Nash Meadow, South Wamborough, Hampshire

Dr D. M. Bryant has commented as follows: 'In my experience, House Martins invariably mate in the nest; this is so for established pairs and (much more obvious) for promiscuous mating attempts by unpaired males with paired females. The aerial aspect of Mr Raynor's observations is obviously unusual, but not impossible: any confusion with adults feeding their young in the air, which is fairly common, seems unlikely. We already have evidence from their behaviour that some young House Martins show precocial development: they help to feed young of subsequent broods; sexual behaviour in advance of full maturity is therefore not unexpected. Alternatively, this could be an autumn resurgence of sexual activity among adults, a phenomenon widespread among temperate-zone birds. That the behaviour des­ cribed occurs in autumn, but not in spring, suggests that it involves birds without a territory (=nest); I feel that it is most likely to involve young from first broods (some of which are still present in September) or from early second broods.' EDS

Roosting behaviour of House Martins The note on roosting behaviour of migrant House Martins Delichon urbica (Brit. Birds 73: 414-415) prompts the following. At about 19.00 GMT on an evening in September 1976, in northeast Hampshire, my wife and I observed a close formation of House Martins circling some elms Ulmus; one by one they dropped into the head of the tree, and did not reappear. Our assumption that they were roosting is reinforced by the fact that the annual build-up of martins in our village is often accompanied by a tendency to sit in a tall ash Fraxinus excelsior during the few days before departure; they do not appear to feed on insects among the leaves, but sit for several minutes before all resuming their flights. E.M. RAYNOR Priors Mead, Nash Meadow, South Wamborough, Hampshire

Hen Blackbird striking human intruder in defence of nest Dr G. Beven's note (Brit. Birds 73: 35-36) prompts me to record the following. On 3rd May 1979, at St Andrews, Fife, I found a female Blackbird Turdus merula on a well-hidden nest about 1 m above ground level, in a clump of roses Rosa and ivy Hedera in the garden of a church. At 19.15 GMT, I returned and found her absent from the nest, which contained two nestlings and one egg. I returned again to ring the young: I put my hand towards the nest, and it was immediately pecked by the female Blackbird; this continued for several seconds until she left the nest, hopping only about Vi m away and remaining 456 Notes in the roses and ivy. When my hand entered the nest to remove the nestlings, the female rushed at it and pecked it several times; while I ringed the nestlings, she remained in cover, constantly uttering alarm calls. There was no sign of a male. I replaced the nestlings and the back of my hand was again pecked. At 11.00 GMT on 7th May, the female was gathering food, and the two young were still in the nest; there was no sign of a male Blackbird. At 13.45 on 10th May, the young had left the nest and there was still a single egg present; when I put my hand into the nest, it was attacked by the female, which had remained unseen. On 14th May, the nest was empty, and the female and one of the ringed young were standing nearby under cover, with a male Blackbird in close attendance. T. W. DOUGALL Department of Geography, The University, St Andrews, Fife KY169AL

Dr C. J. Bibby has commented that this does seem to have been a very aggressive female, but that 'y°u do not have to ring a lot of suburban Blackbird chicks to get pecked'. EDS Song period of Moustached Warbler Dr Colin Bibby, in his informative article on the Moustached Warbler Acrocephalus melanopogon (Brit. Birds 75: 346-359), stated that song may start in mid March. In the Camargue, I have occasionally found this species singing on warm sunny days in February, and I believe that it sometimes sings in January. At this time of year, it is very easy to locate, being the only species singing from reed-beds, no trans-Saharan migrants having yet arrived. Later in the spring, it is difficult to find, even though it recommences singing in mid May. These two song periods may indicate that at least some Camargue birds are double-brooded. Blondel & Isenmann (1981, Guide des Oiseauxde Camargue) suggested that some may even have three broods. TONY WILLIAMS Societ'e Omithologique de France, 55 rue de Bujjon, 75005 Paris, France

Great Reed Warbler attacking Reed Warblers On 10th June 1979, at Brandon Marsh, Warwickshire, we observed a Great Reed Warbler Acrocephalus arundinaceus attack the breeding Reed Warblers A. scirpaceus several times in flight. It grasped one of the latter and then, either by accident or by design, tumbled to the water's surface, where a struggle ensued, each time resulting in the submergence of the captive bird for a second or two before it escaped and flew off. The Reed Warblers were in song and were presumably regarded as competitors by the Great Reed Warbler. W. T.JACKSON and D. A. STONE 4 Aintree Drive, Lillington, Leamington Spa, West Midlands CV32 7TG Whitethroats breeding on Welsh heather moor During 1979, 11 pairs of Whitethroats Sylvia communis bred, and a further six were present, on a grouse moor in east Clwyd. All sites were in long, dense heather Calluna vulgaris, usually with an admixture of bilberry Vaccinium myrtillus and bracken Pteridium aquilinum, and near water courses, usually in hollows; they ranged from 1,000-1,375 feet (300-420 m) above sea level, with most at 1,150-1,300 feet (350-400 m). Similar numbers were present in 1980. In May 1961, on the same moor, I found a nest with four eggs in dense heather; the species was common there in 1965 and 1966. JOHN LAWTON ROBERTS 5 Trej-y-Nant Park, Acre]air, Wrexham, Clwyd LL14 3SR Notes 457 Treecreepers rearing Blue Tit On 31st May 1979, in a small wood near Arkholme, Lancashire, I found a Treecreeper Certhiajamiliaris incubating a clutch of seven eggs in a nestbox. The clutch was photographed. On examination of the photographs, one egg appeared smaller than the others and without the dense zone of spots. On 17th June, the box contained four young Treecreepers and one young Blue Tit Parus caeruleus, all healthy, feathered and about 10-12 days old; I ringed them (and also a brood of 11 Blue Tits in a box about 35 m away). Five days later, the Treecreepers had gone, but the Blue Tit remained; in the space of 15 minutes, Treecreepers were twice seen entering the box with food. On 29th June, the box was empty (as was the Blue Tit box nearby). It appeared that the Treecreepers carried on feeding the Blue Tit when their own young had fledged, and had reared it successfully. There are accounts of young Great Tits P. major being reared by Nuthatches Sitta europaea (Dr C. M. Perrins, 1979, British Tits) and by Robins Erithacus rubecula (Dr J. S. Ash, 1950, Brit. Birds 43: 300). K. B. BRIGGS 26 Hazelmount Drive, Warton, Carnforth, Lancashire LA59HU Derek Goodwin has commented that it is particularly interesting that the young Blue Tit was tended by the Treecreepers even after their own young had left the nest. EDS

Red-backed Shrike with white primary patch A. R. Dean noted, in his 'Field characters of Isabelline and Brown Shrikes' {Brit. Birds 75: 395-406), that 'adult male Red-backed Shrikes Lanius collurio may in exceptional circumstances reveal a trace of white at the base of the primaries.' I was one of a group who made a brief visit to northern Syria on 9th and 10th May 1979. Shrikes were a frequent roadside casualty and we often stopped to inspect the remains. One dead individual on 10th May was a typical Red-backed Shrike in all respects, except that it had a prominent white patch at the base of its primaries, no less marked than that on the adult Isabelline Shrike L. isabellinus shown in plate 151. Professor Dr K. H. Voous has noted that 'widespread hybridisation has been reported' (Brit. Birds 72: 575); our Syrian individual, however, appeared typical in all respects other than its wing patch. I suggest, therefore, that adult male Red-backed Shrikes very occasionally have an obvious white wing-patch. P. A. DOHERTY 15 Garth Road, Leeds LS175BQ

A. R. Dean has commented: 'On Red-backed Shrike Lanius collurio, Brown Shrike L. cristatus and Isabelline Shrike L. isabellinus the bases of the primaries are white, but only on the last species does this regularly show as a white patch on the folded wing. On the first two species, the area of white is normally small, and is therefore covered by the overlying primary coverts, but occasional individuals (especially adult males) may have rather more extensive white which forms a visible feature on the wing. Such an extensive white patch as that described by P. A. Doherty is certainly rare (and in a road casualty the primary coverts may have been displaced), but a similar bird was trapped on Fair Isle, Shetland, in May 1981 (plate 197). Hybridisation is known to produce individuals with an obvious white primary patch yet head and body like adult male Red-backed, but, additionally, such birds normally display rufous tones in the tail (they have been termed 'karelini-type' in some works). An extensive white patch on birds otherwise identical with typical Red-backed seems, however, more likely to represent an extreme in individual variation rather than hybridisation. Such occurrences underline the point made early in my paper that, although a useful clue, undue emphasis 458 Notes

197. Male Red-backed Shrike Lanius collurio with white patch showing at base of primaries, Shetland, May 1981 (Elizabeth Riddijori) should not be placed on the presence (or absence) of a white primary patch.' We have been informed by Nick Riddiford that another Red-backed Shrike with a white patch (about 5 mm below the primary coverts) occurred on Fair Isle in early June 1983. EDS

Great Grey Shrike pellet analysis In March 1979, during a period of extreme snow and ice, a Great Grey Shrike Lanius excubitor appeared on an area of wasteland at Newby, Scarborough, North Yorkshire. From 11th, and daily until 28th, it spent much of its time inside a low thicket of willow Salix scrub, coming out at intervals to watch for prey from a prominent perch. I saw it once take a small rodent, return to the thicket, and pluck at the fur on the rodent's back; it then appeared to swallow its prey whole. On 29th March, I searched the thicket and found four pellets; they were shiny, compact, about 3cm long and 2V2cm at the widest point. Each of three dissected at the Scarborough Natural History Museum contained the entire remains of a field vole Microtus agrestis; as no insect remains were found, it would appear that the shrike had fed exclusively on the voles, which were numerous as evidenced by the many runs seen on the snow- covered observation area. Neither the Museum Curator nor I could find any description of Great Grey Shrike pellets in the literature. MICHAEL FRANCIS Silverdene, Main Road, Crossgates, Seamer, Scarborough, North Yorkshire

David Glue, who published an analysis of 30 Great Grey Shrike pellets from the New Forest, Hampshire, in 1968 (Brit. Birds 61: 468), has commented as follows: 'My analysis confirmed voles as prey items of importance—as implied by The Handbook and the work in Germany by D. Bayer (1950, Kosmos 46: 523)—but suggested perhaps a more varied diet for shrikes wintering in the New Forest. The sample was very small, though, and I have often asked for more pellets (not easy to come by, and difficult to analyse). Microtus remains always seem to "come through" well compared with some other mammals, birds, and especially insects.' EDS Notes 459 Carrion Crows causing death of Grey Heron On 12thjune 1979,1 saw a Grey Heron Ardea cinerea flying east at about 20m over the crest of a low hill in urban Walthamstow, London. It attracted five Carrion Crows Corvus corone and, while attempting to evade them, circled. The crows harassed the heron for ten to 15 minutes, culminating in a more intensive attack when they repeatedly 'buzzed' it. At least one crow possibly alighted on the heron's back and pecked; certainly, very close contact by all five crows occurred, The final attack lasted only about one minute, after which the heron lost flying speed and dived vertically, with its wings half extended, crashing on the flat roof of a building. The crows, noisy throughout, maintained their calling while they descended to attack the body of the dead heron. It is not clear whether the heron was fatally wounded before it crashed; the right humerus, left femur and perhaps other bones were broken on impact. The final attack occurred only 30 m from a crow's nest from which young had fledged earlier. The heron weighed l,800g, within the recorded weight ranges for adults. GRAHAM J. WALTERS 6 Avon Road, Walthamstow, London E173RB