Notes Aberrant Slavonian Grebe A thick-billed and un- familiarly plumaged Slavonian Grebe Podiceps auritus appeared on the open marine bathing-pool at Penzance, Cornwall, on 28th December 1981. It was distinctly odd- looking: rather bulky, with a relatively thick bill, and a generally rather drab, smudgy grey appearance, quite unlike the immaculate black-and-white Slavonians normally encountered in winter. The grebe remained until 14th January 1982, enabling me to note the following details: Crown blackish-grey, rather flat with a greyish black collar, banded by greyish semblance of tippets. Lores smudgy dark white. Upperparts dull grey to black, a little grey. Sides of head dirty white. Streak down white area in wings apparent when stretched hind-neck blackish grey, narrowing towards or flapped. Rear end mottled smudgy white, mantle. Sides of neck blotched and smudgy extending to ventral region. Flanks heavily in appearance, created by lighter and darker mottled dark grey to black. Underwing pale grey areas; below this, a wide but ill-defined or whitish. Iris ruby-red. Bill dark and thick. Fjeldsa (1973) recognised three races of Slavonian Grebe, with the thicker-billed populations ('arcticus') being the breeding form of Iceland, northern Norway and Scotland. BWP (1:105) states, however, that, in view of differences being slight and partly clinal, naming of subspecies is unnecessary. Details of the Penzance grebe were forwarded to Dr K. E. L. Simmons, who commented 'The bird should have been in adult winter or first-winter plumage . . . and should have been matched by specimens amongst the small-billed birds (there being no important plumage differences between the forms). So the question really is: was it an aberrantly plumaged, large-billed Slavonian Grebe or a hybrid— presumably with a Red-necked Grebe P. grisegenaV BEKNARD KINO Gull Cry, 9 Park Road, Newlyn, Penzance, Cornwall TR185DZ

REFERENCE FJELDSA, J. 1973. Distribution and geographical variation in the Horned Grebe. Omis Scand. 4: 55-86.

Although it was seen by other observers, neither we nor Mr King have been able to track down any photographs of this bird. We hope that any similar individual will be described, sketched and photographed; we shall welcome details. Ens

continued

142 Notes 143 'Natural' hazard causing death of Sparrowhawk On 4th April 1982, at Tophill Low, Humberside, I found an adult male Sparrowhawk Accipiter nisus entangled in a hedge of privet Ligustrum with some hawthorn Crataegus monogyna about 2m high. The hedge runs along the side of a wide dyke. D, E. Glue and D. N. Weir (Bird Study 18: 137-146, 147-154) stressed the proneness to accidents implicit in the Sparrowhawk's way of life; they listed collisions with netting, fences or windows, but implied that 'natural' obstacles do not present a hazard. It is, however, possible, or even likely, that collisions while hunting form a significant proportion of deaths of this raptor. R. A. REESE The Computer Centre, The University of Hull, Cottingham Road, Hull HU6 7RX

Shell-dropping by Ospreys Hard-shelled food items are dropped and broken open by some birds of prey. Bearded Vultures (Lammergeiers) Gypaetus barbatus drop mammal bones and tortoises Testudo (e.g. Boswall & Crook 1968; Leshem 1980), Egyptian Vultures Neophron percrtopterus drop tortoises and dabb-tailed lizards Uromastix aegyptius (Ilany 1982), and Golden Eagles Aquila chrysaetos drop tortoises (Fischer et al. 1975; Leshem 1979). Indeed, Golden Eagles near Har Gilo, Jerusalem, Israel, cracked open 107 tortoises during the 1979 breeding season. Similar behaviour by Ospreys Pandion haliaetus, involving the dropping of the shells of the large conch Lambis truncatus, was seen by Y. Levi (in litt.) in 1974 on Tiran off the southeast coast of Sinai. Tiran is a treeless island holding 25-30 pairs of ground-nesting Ospreys, which feed mainly on fish caught around the offshore coral reefs. Whether one or more individual Ospreys were involved is unknown, but the behaviour was always the same. The raptor would position itself, holding the conch in its talons, 30-40 m above a large 200-litre drum filled with concrete; the conch was then dropped, shattering on impact when it hit the drum. This behaviour was observed several times and the drum was surrounded by the remains of dozens of shells, all of the same species of conch. Lambis truncatus reaches a size of 30cm and is found in shallow lagoons in the reef area. It is also eaten by the local Bedouins. This appears to be the first recorded instance of such behaviour by Ospreys. Yossi LESHEM Israel Raptor Information Centre, Society for the Protection of Nature in Israel, Har Gilo Field Study Centre, Doar na Harei, Jerusalem 91076, Israel

REFERENCES BOSWALL, J., & CROOK, J. H. 1968. Bone-dropping behaviour of the Lammergeyer (Gypaetus barbatus). Abstracts XlVCongr. Int. Om.: 43. FISCHER, W., ZENKER, D., & BAUMGART, W. 1975. Ein Beitrag zum Bestand und zur Emahrungdes Steinadlers (A. chrysaetos) aufder Balkanhalbinsel. Beitr. Vogelk. 21:275-287. ILANY, G. 1982. Egyptian Vultures and dabb lizards. Israel Land and Nature 8: 37. LESHEM, Y. 1979. Golden Eagles in our backyard. Israel Land and Nature 5: 70-75. 1980. [The bearded vulture—prince of the cliffs.] Israel Land and Nature 23: 22-28. (In Hebrew) 144 Notes Role of male Kestrel during incubation The role of male Kestrels Falco tinnunculus in incubation is unclear. Richmond (1959) stated that there is no fixed rule, but that some males are 'assiduous sitters' while others take no part at all; Newton (1979) that they will sit while the female is feeding; Brown (1976) that they will take a small part in incubation; and Cramp & Simmons (1980) that they occasionally incubate for a brief period only. At 14.50 GMT on 10th June 1978, near Owslebury, Hampshire, I visited an active Kestrel's nest at the edge of a mixed woodland adjoining pasture and fields and directly opposite an electricity pylon. On my arrival, the female appeared over the field about 200m from the nest tree, giving a food call. She was joined by the male, who had come off the nest, crying loudly, and both alighted 3-4m from the nest; there, the male snatched the prey in a noisy encounter, whereupon the female flew straight to the nest and began to incubate; the male devoured a small mammal, before flying off at 14.55 hours. No more activity ensued until 16.16 hours, when the male reappeared and sat silently on the pylon until 16.29 hours. During this period, I could clearly see large and well-developed brood patches on his underside. He returned at 16.41 hours and flew into the nest tree, where he was joined by the female, who had just left the nest to receive the prey. The male then proceeded to the nest, and after about two minutes began to incubate. The female ate the prey and flew off a little later. This pattern of incubation alternating between the sexes was observed on two subsequent visits, during which the sequence was broken only once, when the female remained on the nest for two sittings. Such observations offer clear evidence of shared incubation, and, indeed, rigid alternation at the nest by both male and female. In addition, it is evident that this extended to a level where both sexes brought prey to their incubating partner at nest relief. On 2nd July, the nest was found abandoned, and, on 5th, desertion was confirmed; no reason for this was established. During 1975-78,1 observed a total of 36 active Kestrels' nests, and on no other occasion was there any evidence of a male incubating. The benefits of the female alone incubating have been stated by Newton (1979) as: (I) total food needs of the pair are reduced, (2) allowing the female to accumulate larger body reserves for breeding, if the male feeds her, and (3) the larger female being always present to defend the nest. The male Merlin F. columbarius may take up to one-third of incubation duties during daylight hours (Brown 1976; Newtonrta/. 1978); the male Kestrel is equally capable of covering the eggs, as shown by the case in captivity (Haigh 1973) in which a male incubated, brooded and reared a family after the female had escaped. Sexual differences in degree of aggressiveness in Kestrels are small; for nest defence, therefore, each sex is equally suited and each will participate (Petersen 1956). In areas where high prey density occurs, the reduction in food needs may be unimportant as the male could provide easily enough prey. (The pair I observed was part of a population with a density of one pair per 394 ha, the third largest on record, suggesting that prey density was high.) The most essential factor in the benefit of female Kestrels incubating seems, therefore, to be the maintenance of their body reserves during this period. This is facilitated by the male providing the Notes 145 prey, since male Kestrels do not acquire their reserves before egg-laying, In species where males have an equal share in incubation and brooding (e.g. vultures Gyps), males, too, acquire such reserves (Newton 1979). I should like to thank Dr Rory Putman for advice on the preparation of this note. C. G. PACKHAM 10 Cleveland Road, Midanbury, Southampton S022AN

REFERENCES BROWN, L. 1976. British Birds of Prey, London. CRAMP, S., & SIMMONS, K. E. L. (eds.) i960. The Birds of the Western Palearclic. vol. 2. Oxford. HAIGH, R. 1973. Captive Breeding of Diurnal Birds of Prey 1 (4): 13. NEWTON, I. 1979, Population Ecology of Raptors. Berkhamsted. , MEEK, E., & LITTLE, B. 1978. Breeding ecology of the Merlin in Northumberland. Brit, Birds 71: 376-398. PETERSEN, C. M. 1956. Ynglebiologiske studier over Tdrnfalken (Falco tinnunculus L). i Kobenhavn [Studies of the breeding biology of the Kestrel in Copenhagen]. Dansk Om. Foren. Tidsskr. 50: 134-159. RICHMOND, \V. K. 1959. British Birds of Prey. London.

Identification of a first-winter Sora I was interested to read the note by P. J. Roberts (Brit. Birds 77: 108-112) on the identification and ageing of a first-winter Sora Porzana Carolina which was trapped on Bardsey, Gwynedd, on 5th August 1981. Neither this bird, being trapped, nor the previous one on St Agnes, Isles of Scilly, from 26th September to 9th October 1973 (Wallace 1980), allowed prolonged field views, so it seems worth recording the details of a first-winter Sora which was present on the Great Pool, Tresco, Isles of Scilly, on 19th and 20th October 1983. It must be remem­ bered, however, that this individual was seen much later in the autumn than the preceding two. It was watched initially sneaking along the edge of the reeds at a distance of about 150m. At this range, the conspicuous white undertail-coverts immediately attracted attention and separated it from Spotted Crake P. porzana, but these were accentuated by an erect and continuously flicked tail. When moving through thicker reeds, it could sometimes be followed only by watching for the flicking white undertail-coverts. The tail itself looked long and pointed, recalling Water Rail Rallus aquaticus rather than Spotted Crake. Wallace also noted an apparently longer tail on the St Agnes individual, but it is not known to what extent this may be an illusion accentuated by the whiter undertail-coverts. The Tresco Sora showed obvious black lores, forming a solid patch between the eye and the bill, and this, coupled with a thick-based, heavy, lime-green bill, gave it a distinctive facial appearance even when viewed at a distance. It was, therefore, the combination of the undertail-coverts/tail and the facial colour/bill which facilitated the initial identification. A little later, a number of birders were able to obtain confirmatory views down to 10-15m from the seclusion of a shooting butt. The black lores were again conspicuous and they extended below the bill to form a narrow connecting 'chin strap'. Unlike the previous two, the throat was essentially grey (only slightly paler than the grey breast) and lacked a dark central furrow. The heavy-based bill was entirely lime-green, lacking the orange base of Spotted Crake as well as the yellow base shown by the previous two 146 Notes first-years. Other head markings were also distinctly different from Spotted Crake: it showed a thin, but distinct, black central crown stripe and a small, but noticeable, white rear 'eyebrow'. There was no white head spotting typical of Spotted Crake. The base of the undertail-coverts was seen to be rich buff, similar in shade to that of a Spotted Crake, but the outer and central feathers were conspicuously creamy white (fig. 1). Without any comparisons, it was difficult to evaluate its size, although it looked bulkier and probably longer-necked than Spotted Crake.

Fig. 1. Undertail of Sora Porzana Carolina, Scilly, October 1983, showing rich buff base and white sides and tip (sides crossed by faint black flecks) (K. E. Vinicombe) Wallace emphasised the importance of the plain tawny-brown wing- coverts on the St Agnes bird. Although a diagnostic difference from Spotted Crake, this was practically valueless as a field character on the Tresco bird. This area certainly was not visible at any distance, the reason being that the coverts were almost completely hidden by the overlying scapulars and the fluffed-up flank feathers. The plain coverts were, however, occasionally visible as a narrow, unmarked wedge, blunt and pointing backwards, when the overlying feathers sometimes became separated. A feature which we were unable to test was the obviousness of the white along the leading edge of the open wing. Spotted Crake shows a thick white leading edge to the lesser wing-coverts (extending around the front of the wing from the leading lesser underwing-coverts) and this is usually con­ spicuous in flight. The photograph of the Bardsey Sora. (Brit. Birds 77: plate 38) fails to show white leading lesser coverts, and Wallace did not mention it in his paper. I am very grateful to Peter Colston, who inspected skins of both species at the British Museum (Nat. Hist.). He found that, while both show white, it is broader and more prominent on Spotted Crake. While this difference cannot be regarded as a cast-iron field character, a flushed crake failing to show an obvious white leading edge to the wing would clearly be worth following up. K. E. VINICOMBE 49 Trelawney Road, Cotham, Bristol BS66DY REFERENCE WALLACE, D. I. M. 1980. Sora Rail in Scilly and the identification of immature small crakes. In SHARROCK, J. T. R. (ed.) The Frontiers of Bird Identification, pp. 231-236. London.

Foraging and hunting efficiency of Caspian Tern During September and October 1981, in the Gulf of Suez close to Adabiya, Egypt, I watched the foraging behaviour of Caspian Terns Sterna caspia. This is a resident breeding species in the Red Sea and along the eastern coast of Sinai (Meininger & Mullie 1981); during the autumn and winter, there is an influx from the Baltic (Staav 1977) and the Crimea (Moreau 1972). The status of those I observed is not known. Up to six adults could be seen Notes 147 fishing together, usually within 100 m of the shore. From a height of 10-30 m, they searched the water below in leisurely flight. When prey was spotted, they performed a nearly vertical swoop with half-folded wings which were partly spread just before reaching the surface, resulting in a big splash; the tern sometimes submerged completely, and laborious wing- flapping was needed to gain height again, while the feathers were vigorously shaken. Quite often, the dive was not completed, but checked and converted into a swerve on stiff, outstretched wings just over the water for 5-25 m, followed by powerful wingstrokes to gain height. During a total of 160 minutes' observation on nine days, I recorded 61 diving attempts: 25 were completed, of which 16 resulted in a visible catch. When seen, the prey was always fishes of about 5-12 cm, but very small prey may have been swallowed immediately after catching. It seemed that a dive was completed only when the tern was pretty certain of a successful strike, thereby saving itself the trouble of taking off from the water after having lost speed. Another hunting method was observed on receding tides when small pools, sometimes containing fishes, were left on the beach. The terns searched the shore in low, leisurely flight, landed, and picked up and swallowed edible objects. Sometimes they hunted the shore by walking short distances (cf. Bent 1963), but this hunting method was comparatively rarely ob­ served. ROB G. BIJLSMA Bovenweg 36,6721 HZ Benmkom, The Netherlands REFERENCES BENT, A. C. 1963. Life Histories of North American Gulls and Terns. New York. MEININOER, P. L., & MULUE, W. C. 1981. Significance ofEgyptian Wetlands as Wintering Areas for Waterbirds. Holy Land Conservation Fund, New York. MOREAU, R. E. 1972. The Palaeardk-African Bird Migration Systems. London & New York. STAAV, R. 1977. Etude du passage de la Sterne caspienne Hydroprogne caspia en Mediterranee a partir des reprises d'oiseaux bagues en Suede. Alauda 45: 265-270.

Dr Euan K. Dunn has commented as follows: 'I think that the concept of the "intention dive" and whether or not it should be considered a failed dive are of interest. If the tern was forced to dive from quite high, it did the right thing, in terms of conserving energy, in being conservative about committing itself to entering the water unless catching success was more or less certain (16 successful dives out of 25 is a high rate). The ground foraging by this species is especially interesting, and apparently not recorded before in the literature. Unfortunately, this note was received too late for details to be included in the forthcoming volume 4 of BWP.' EDS

Several 'adult' Common Terns attempting to feed juvenile K. V. Cooper (Brit. Birds 76: 348) described from one to four 'adult' Common Terns Sterna hirundo presenting fish to a begging juvenile, and Dr E. K. Dunn commented that he had frequently seen this behaviour by Sandwich Terns S. sandvicensis. Since 1967, under the direction of Helen Hays of the American Museum of Natural History, I have participated in studies of tern biology on Great Gull Island, in Long Island Sound, New York, and have many times seen the behaviour described by Mr Cooper. Dr Dunn 'assumed that the strange "adults" attempting to feed were either failed breeders or immatures, deduced from their general hesitancy and tentative behaviour in the colony area.' A large majority of the Common Terns on Great Gull Island have been colour-ringed with individually unique 148 Notes

combinations, both as adults trapped on the nest and as pre-flying juveniles. Each year there is an influx of pre-breeding terns relatively late in the season; three-year-olds frequently, and two-year-olds occasionally, nest or attempt to nest; those that do not will hang about in the colony, and it is these that present fish to downy young or juveniles. Even if not colour- ringed, many (but not all) two-year-olds can be recognised as such by their white foreheads and dark carpal bars. The reaction by the young when approached is variable. Downy chicks and younger juveniles tend to flatten down and 'freeze', whereas older juveniles, as Dr Dunn states, may act aggressively towards the intruder. It is, however, difficult to distinguish between this aggressive behaviour and the normal enthusiastic open-billed begging by large juveniles that rush to meet an incoming parent. In any case, the intruder flies off, or at least backs away; should one of the parents arrive, it will dash at the intruder and often chase it for some distance. I agree that the sight of the young seems to trigger a feeding reaction by the pre-breeding terns, but this reaction is poorly developed: as if the intruder 'knew enough' to present a fish to the chick, but not to try actually to feed it. The tern is easily frightened off, even if the chick continues to beg, but typically it circles the colony once or twice, lands in the identical spot and proffers the fish again. Occasionally, after several presentations, the pre- breeding tern will swallow the fish itself; more frequently, it disappears from the area of the colony visible to the observer. Mr Cooper's observation of as many as four terns simultaneously attempting to feed a juvenile is rather unusual. He implied that one or two of these were the parents, in which case it is surprising that no hostility to the non-parents was exhibited. I have seen three non-parents surrounding a juvenile, but a single individual is most frequent. My observations, like those of Dr Dunn, have been in, rather than away from, the colony, but this may be because the observation towers on Great Gull Island are situated for optimum visibility of nesting areas. This is contribution no. 66 from the Great Gull Island Project, American Museum of Natural History. KENNETH C. PARKES Carnegie Museum of Natural History, Pittsburgh, Pennsylvania 15213, USA

House Martins' nests on ships With reference to Dr Gox's note on the nest of a House Martin Delichon urbica on a Scandinavian ferry {Brit. Birds 76: 232-233), on 26th August 1980, on board the same ferry, I photo­ graphed an incomplete House Martin's nest in a location similar to but not identical with that in Dr Cox's photograph (76: plate 92). At the time, I presumed that it was an uncompleted 1980 nest: the construction appeared to be new, but there were no droppings and no sign of the building birds. I. G. JOHNSON 3 H'oodlea Grove, Northwood, Middlesex HA62DW

Three fairly large car ferries sail between Spodsbjerg (Langeland) and Tars (Lolland), a Danish internal route of 14 km and a journey of 45 minutes (a round trip of two hours). During July 1983, under the roof of the car deck of one ferry, I noticed one House Martin's nest containing young and, Notes 149

adjacent to it, an old, apparently disused nest The adults fed the young while at the harbour at Spodsbjerg, but I did not notice any activity once the boat was out of port. F. Guldbrandsen, the Master of the vessel Taars, informed me (in litt.) of the following. In 1983, there were seven or eight nests, all with young; he believed that all but one young fledged. This particular ferry is used only during the peak season, and is otherwise docked at Spodsbjerg. It has been used by House Martins since 1973, and the nests usually contain young when it is brought into service. The adults visit the boat only at Spodsbjerg, but will fly out to it before it comes into port and enter the boat as soon as the bow-gate is opened. Hr Guldbrand- sen's letter implied that the ferry company deliberately does not use this boat at the beginning of the season because of the existence of the nests. DAVID B. COLLINGE Department of Genetics, University of Newcastle-upon-Tyne, Ridley Building, Claremont Place, Newcastle-upon-TyneNEi 7RU

The Sussex Ornithological Society's files for 1973 contain a record of three pairs of House Martins nesting on the cross-channel ferry MV Senlac while it was berthed at Newhaven. Two nests were on pipes under the wing of the bridge and another in a similar position on 'A' deck at the stern. The adults did not make the trip of 120km to Dieppe, but left the vicinity of the ship when it reached the Newhaven breakwater and awaited its return nine hours later. At least one of the nests was known to have been successful. S. W. M. HUGHES 6 West Way, Slinfoid, Horsham, West Sussex

On 2nd June 1973, I observed a pair of House Martins building a nest (about two-thirds completed) on a ferry berthed at Newhaven. When the ferry sailed for Dieppe, one of the martins stayed with it for about 20 minutes before returning to land. DAVID S. MELVILLE c/o 44 The Ridgeway, Tonbridge, Kent TN104NJ Full details of similar records will be welcomed. These will not be published separately, but will be filed for possible eventual summary. EDS

Territorial behaviour of Ring Ouzels The behaviour of two male Ring Ouzels Turdus torquatus described by R. P. S. Wolsey (Brit. Birds 75: 382), is not uncommon, but I do not accept the assumption that they were necess­ arily migrants. In North and West Yorkshire, the first Ring Ouzels arrive within a few days of 15th March, and by the date of the observation (19th April) most are well established. During an ongoing study since 1979, involving over 140 pairs of this species in Yorkshire, I have observed similar aggressive behaviour between males on numerous occasions. In 1982, an area of about 2 km X 1 km supported three pairs, two on one side of a steep-sided valley with a major road in the bpttom and one (the aggressor) on the other. On a number of occasions on 6th June, the aggressor flew across the valley into the area occupied principally by one of the other ouzels, which it harassed for periods of up to 15 minutes before being chased back to its own side. Ring Ouzels are much more colonial when nesting 150 Notes than is generally supposed, and are not strictly territorial. In 1982, an area of approximately 4 km X 1 km supported ten pairs, which continually over­ flew and fed in the areas of each other's nests; two nests were only 100m apart. Ring Ouzels centre their activity around their own nesting sites, and the male usually sings from the nearest prominent feature; two or more individuals will often 'sing against each other', IAN APPLEYARD Pine Court, Sharow Cross, Ripon, North Yorkshire HG4 5BQ

Orphean Warbler in Scilly From 16th to 22nd October 1981, an adult male Orphean Warbler Sylvia hortensis was present in the Higher Moors/ Holy Vale area of St Mary's, Isles of Scilly. We first saw the warbler about 15.10 GMT on 16th as it flew across the path between Higher Moors and Holy Vale. Even in flight, the large size, white outer tail feathers and black head made us pretty sure it was a male Orphean Warbler, a species we had both seen on the Continent. Brief views were had as it dropped into a bramble patch. As is usual in October on Scilly, a number of birders were close by, and were quickly shown where the bird had landed. Fortunately, it gave excellent views as it fed sluggishly on the outside of the bramble bush at a distance of about 10m. During its stay, it spent most of its time in large bramble patches and was eventually seen by about 400 birders. It was photographed by Peter Basterfield (Brit. Birds 75: plate 212). The last sighting was near Holy Vale on 22nd October. We noted the following details: Large Sylvia warbler, larger than Blackcap S. flight. Underside of tail plain blue-grey. atricapilla, being closer in size to Barred Underparts creamy, washed grey on flanks, Warbler S. nisoria. Head rounded, sooty becoming buffy on undertail-coverts. Promi- black, fading into grey on hind crown, nape nently demarcated white throat. Bill large and behind ear-coverts. Mantle, rump and for a warbler; upper mandible dark, lower uppertail-coverts dull, pale grey. Primaries mandible blue-grey. Legs grey, strong- and secondaries with grey-brown tinge. looking. Eye brown, with thin white ring on Secondaries tipped pale. Tail long, grey, outside edge of iris, with white outer tail feathers prominent in This is the fifth accepted record of Orphean Warbler in Britain and Ireland, the previous ones being at Wetherby, Yorkshire, on 6th July 1848; at Portland, Dorset, on 20th September 1955 (Brit. Birds 49: 180); at Porthgwarra, Cornwall, on 22nd October 1967 (Brit Birds 63: 178-179); and at Stiffkey, Norfolk, on 17th August 1981 (Brit. Birds 75: 522). j. M. TURTON and P. K. GREAVES 119 Hough Lane, Wombwell, Barnsley, South Yorkshire S730EG

Carrion Crow taking seabird eggs During June 1980, while carrying out a population census of Guillemots Una aalge on Hermaness, Unst, Shetland, I observed Carrion Crows Corvus corone of the race comix taking seabird eggs on three occasions: twice from Guillemots and once from Fulmars Fulmarus glacialis. I can find only one reference to similar behaviour (T. R. Birkhead, 1977, J. Anim. Ecol. 46: 751-764). In the case of the Guillemots, the crow alighted on the cliff close to an incubating adult; this Notes 151 caused much anxiety among incubating auks for some distance on each side of the crow, and many were seen to 'alarm bow' (see Birkhead 1977). For several seconds after landing, the crow appeared to pay no attention to the Guillemot, while the latter alarm bowed continuously. When the crow did face the Guillemot, the auk attempted to withdraw its head and neck as far from the crow as possible while still covering die egg; the two remained in this position for a second or two before the crow suddenly lunged forward, seized the Guillemot by the wing and threw it off the ledge. The crow broke open the egg and began to devour the contents in situ. In the case of the Fulmar, the crow alighted beside one of a group of incubating birds nesting on a grassy slope close to the cliff where the Guillemots had been attacked. It behaved in the same manner as towards the Guillemot. It is interesting to note that the Fulmar did not attempt to 'oil' its attacker. Again, the crow consumed the egg contents on the spot. To what extent this behaviour by crows is common in Shetland is not known. At one time, piles of egg shells (mostly of Guillemot) found on the tops of the Hermaness cliffs (J. D. Okill in litt.) were accounted for by suggesting that scavenging birds (gulls Lams, crows, Ravens C. corax) had found eggs at the base of the cliffs or taken deserted eggs to the cliff tops and eaten the contents. The present observations may point to an alternative explanation. T. R. Birkhead {in litt.) has seen crows on Skomer, Dyfed, attempting, without success, to rob Guillemot nests. He also described a particular pair of Carrion Crows of the race corone which co-operated in robbing Razorbills Alca torda of their eggs: they landed beside a Razorbill's nest crevice and began 'taunting' the occupant until it lunged at them, whereupon one crow grabbed the auk by the breast feathers while the other began to pull it from the crevice; as soon as the Razorbill had been put to flight, the crows consumed the contents of the egg. Guillemots breeding in low densities are in greater danger of losing eggs to predators than are those which nest in areas of high breeding-bird density (Birkhead 1977). My observations accord with this generalisation: although the Guillemots which had their eggs taken were part of very dense colonies, they were occupying peripheral sites along the edge of the nesting ledge. I should welcome details of any similar observations, especially notes on known cases of increase in the incidence of this behaviour in a given locality. JOHN MCKEE 12 North Park, Symbister, Whakay, Shetland ZE29AF Feeding methods of coastal Carrion Crows During 1978-82, at Filey Brigg, North Yorkshire, I noted various feeding methods by a pair (the same?) of Carrion Crows Corvus corone which regularly frequented the seashore. By far the most common method was the taking of fish offal washed up along the beach, for which they competed with gulls Lams, but they also opened molluscs around the rocks (cf. Brit. Birds 72: 553) and occasionally robbed Oystercatchers Haematopus ostralegus of their already- opened molluscs. On 6th May 1982, however, I saw a Carrion Crow standing up to its belly in water in a rock pool. It was jumping up and down, stabbing with its bill into the water, its head going well under the surface. It continued this behaviour for about two minutes, wading across the pool, 152 Notes when the water at times reached above its folded wings. With one of the stabs under water, the crow emerged with a fish about 7 cm long in its bill and flew to a nearby rock; the fish was still alive and was curling around the crow's bill. The crow placed the prey, probably a species of blenny (Blen- niidae), under its left foot and repeatedly hammered it with its bill until the fish stopped moving; it then tore off and ate pieces. Carrion Crows have previously been noted taking food from water (Brit. Birds 40: 158, 245; 41: 278; 44: 323; 49: 91) and diving feet-first into water after fish (69: 273), but the crow at Filey seemed to be driving the fish across the rock pool until it was in a position to be caught. The crow's repeated unsuccessful stabs into the water could indicate that it had not made allowances for the refraction of light and therefore could not estimate the position of the fish until it was restricted to a small area. P. J. DUNN 16 Southwold Rise, Southwold, Scarborough, North Yorkshire Y0113RB