Notes Little sunning in winter At 11.30 GMT on 4th November 1988, in Chichester Harbour, West Sussex, I observed three Little Grebes rujkollis loafing between the yachts in Birdham marina. The yachts were moored closely, side by side, and each was in a similar position less than 1 m from the bows of larger vessels. All three grebes had been stationary for some time, when first one and then a second started to dive; after each dive they returned to their former positions. The third never moved off station, and remained motionless except for one brief bout of preening; this individual was facing into the sun, with its rear towards the vessel, and had both its tail- coverts and its wings slightly raised. I concluded that all three grebes were deliberately exposing themselves to the weak, but nevertheless warm, winter sunshine on a morning when the air temperature was still very low following an overnight frost. Furthermore, their exact positioning was clearly deliberate: providing complete protection from the prevailing breeze, direct radiant heat from the sun, and reflected radiation from the bows of the vessels (which, by virtue of their shape, would have been acting as parabolic reflectors). The general literature on sunning, and specifically that relating to grebes (Storer et al. 1975), gives no examples of the use of reflected sunlight. The circumstances and the grebes' behaviour, however, seem to fit well with the sun-basking classification, proposed by Simmons (1986), for the purpose of thermoregulation. Coots Fulica atra and Tufted Ducks Aythyafuligula were also present on the water: both were keeping in the sun, preening and diving, but they were concentrated in the channels of open water, well away from any vessels. S. W. M. HUGHES 6 West Way, Slinfold, Horsham, West Sussex RH13 7SB

Dr K. E. L. Simmons has commented: 'These winter observations nicely confirm my suggestion that grebes sun themselves mainly in to gain heat. Such sun-basking, as Storer and his co-authors have shown, occurs only in the smaller species of grebes, with one significant exception—the Hooded Grebe P. gallardoi of Southern Patagonia, which inhabits a particularly cold and windy environment (Storer 1982). Like the smaller species, the Hooded Grebe has the skin of the back and rump and the bases of the overlying feathers darkly pigmented, an adaptation for absorbing solar heat.' Ens

REFERENCES SIMMONS, K. E. L. 1986. The Sunning Behaviour of : a guide for ornithologuls. Bristol. STORER, R. W. 1982. The Hooded Grebe on Laguna de los Escarchados: ecology and behavior. Living 19: 51-67. , SIEGFRTED, W. R., & KINAHAN, J. 1975. Sunbathing in grebes. living Bird 14: 45-56.

Immature attacking Black-headed Gull On 13th Novem­ ber 1988, along the River Don in industrial Sheffield, South Yorkshire, I watched an adult and four immature Little Grebes Tachybaptus ruficollis 34 Notes 35 loafing at a weir-pool close to their breeding territory. About a dozen Black-headed Gulls Lams ridihundus were feeding above the pool when one gull, hovering within 1 m of the water surface, was attacked by a nearby immature grebe; the latter jumped at the gull, almost (but not quite) completely leaving the water. This was repeated three or four times within about two minutes, the grebe never quite managing to make contact, until the gull moved to a different part of the pool. The gull had shown no aggression towards the grebe, either before or during the seemingly unprovoked assault, although the grebe presumably felt threatened by its close presence. I have not previously witnessed this type of aggressive behaviour by Little Grebes, nor is there any reference to it in BWP (vol. 1). A. J. MORRIS 4a Raven Road, Sheffield S7 ISB

Concealing posture of Mallard On 12th November 1988, I was walking along the banks of Skirden Beck, near its confluence with the River Ribble at Bolton by Bowland, Lancashire. This stretch has no emergent or overhanging vegetation. As I rounded a bend, something about 25 m ahead moved rapidly to the bank, where the movement ceased and I was unable to detect what had caused it. I raised my binoculars and was surprised to see a male Mallard Anas platyrhynchos which had 'frozen' in an elongated posture, with its head and neck resting on the bank and its body still floating in the water. When I lowered my binoculars again, the dark head looked just like one of the many stones in that area, while the pale- coloured body merged with the water; with the naked eye it was impossible to tell what the object was until I was much nearer. The Mallard finally sprang from the water when I was only about 4 m away. A. A. COOPER 28 Peel Park Avenue, Clitheroe, Lancashire WI7 IET Feeding groups of Common Scoters containing other species BWP (vol. 1) states that Common Scoters Melanitta nigra form dense rafts in winter, but tend to feed in smaller, more scattered groups whose individuals make synchronised mass dives. No mention is made, however, of other species feeding in these groups. In 1986/87, about 500 Common Scoters wintered in Luce Bay, Dumfries & Galloway. Feeding parties were sometimes widely scattered, but, from November 1986 to February 1987, one small group of up to 42 scoters regularly fed 100-200 m off a rocky shore. At times, six other species fed in these groups of scoters (table 1),

Table 1. Composition of feeding groups of Common Scoters Melanilla nigra and other species in Luce Bay, west Galloway, in winter 1986/87 Dale Composition of feeding groups 15 Nov 86 17 Common Scoters, 8 Red-throated Divers Gavia stellata 28 Dec 86 9 Common Scoters, 1 Red-throated Diver, 2 Shags Phalacrowrax arttloteUs, 1 Razorbill Alca tarda 4 Jan 87 15 Common Scoters, 2 Red-throated Divers, 1 Great Northern Diver O. immer 12 Jan 87 42 Common Scoters, 1 Podkeps cmtatus 14 Feb 87 12 Common Scoters, 3 Great Crested Grebes 21 Feb 87 9 Common Scoters, 3 I.ong-tailed Ducks Clangula hyemalis 36 Notes and, when feeding, all the species would dive close together, sometimes in a tightly knit group, diving and surfacing synchronously. They could have been feeding on molluscs and/or fish, but none was brought to the surface. Similar behaviour occurred on four dates in the winters of 1987/88 and 1988/89, when up to four different species again fed in close proximity; the largest group, on 25th November 1988, comprised 20 scoters, two Great Crested Grebes Podieeps cristatus, eight Slavonian Grebes P. auritus and two Shags Phalacrocorax aristotelk. There was no apparent advantage to any of the species involved in feeding together; presumably, they were all exploiting an available food source. R. C. DIC K s o X Lismore, New Luce, Newton Stewart OG8 OAJ

Aerial prey-capture technique of little Gull On 7th April and 8th September 1988, during two visits to Crosby Marina, Liverpool, Merseyside, I watched groups of, respectively, 17 and six Little Gulls Lams minutus feeding in a manner unlike that described in the literature. Rather than dipping down to the surface and snapping up insects, they rose sharply a metre or so from horizontal flight and then threw their heads right back, opening their bills wide in a flycatching snap, before dropping back on to their original flight path. So distinctive was this action, often with several individuals independently involved in flights containing a number of flycatching peaks, that the gulls could be picked out quite easily from the opposite side of the marina 0.8 km away. On both occasions, flying insects were abundant over the marina. P. I. M ORRIS Caughall Farmhouse Cottage, Caughall Road, Upton-by-Chester, Cheshire CH2 4BW

Other gulls, perhaps especially Black-headed L. ridibundus,are , of course, frequently to be seen feeding in flight on swarming flying ants, particularly in late summer. Ens

Herring Gull using wind shear over land A flight technique used almost exclusively by the larger seabirds exploits vertical wind shear (the change in wind speed with altitude) in the atmospheric surface boundary layer immediately above the ocean. Such a technique, known as dynamic soaring, is probably unusual in its pure form, as the use of air currents deflected upwards by waves plays a significant part in this method of energy conservation. I should therefore like to place on record an event observed and described to me by A. W. Grice. Around midday on 4th September 1988, a Herring Gull Lams argentatus flew south across an airfield in Fife, apparently exploiting vertical wind shear. The wind direction and speed at 10 m above the ground (approximately the maximum altitude reached by the gull) were SW 10 m/s, with gusts to 15 m/s (force 5 to 7). From a level just above the ground, the gull gained height by flapping into the wind; near its maximum altitude, the flapping eased, and the gull then glided down to the ground at about 90° to the wind, whereupon it turned again into the wind to repeat the process a further three times. Apart from a tarmac runway, the terrain over which the Herring Gull flew was flat and grassy, so that, although some turbulence was present, organised thermal Notes 37 upcurrents were considered to have been absent. Some of the power used by the gull to gain height was obviously provided by the flapping, but otherwise this was clearly a case of exploitation of wind shear, with the wind speed close to the ground reduced by friction, a fact that AWG was quick to realise as he made the observation. I can find no specific reference to gull flight across the wind in this manner, and none at all of any species doing this over land. The normal lack of uniformity in land surfaces probably precludes such a flight technique in strong winds, owing to the formation of eddies in airflows over broken terrain, while the flow over flat surfaces more closely resembles that over a smooth sea. NORM AN EI.KINS 18 Scotstarvit View, Cupar, Fife KY15 4DX

Dr J. M. V. Rayner has commented that he is unaware of any previous reports of dynamic soaring by gulls, or by any species over land. EDS

Breeding-range changes of Red-rumped Swallow in Yugoslavia Since the 1950s, the Red-rumped Swallow Hirundo daurica has been recorded in increasingly greater numbers throughout Europe far outside the borders of its usual breeding area (e.g. Dymond et al. 1989). This has coincided with northward expansions of the breeding range. Prior to this range expansion, the Red-rumped Swallow bred in Yugoslavia only in the south, in Montenegro (Grossmann 1910; Rohacek 1916; Reiser 1933) and Macedonia (Makatsch 1950)(fig. 1). A scatter of

Fig. 1. Breeding distribution of Red-rumped Swallow Hirundo daurica in Yugoslavia up to 1950. Small dots show breeding records; large dots indicate non-breeding records 38 Notes non-breeding records outside the breeding range, in Dalmatia (Tutman 1956), Istria (Bernhauer 1957) and Serbia (Matvejev 1957; Antal et al. 1971), was the first indication of a spread (fig. 1). Range expansion developed in two main directions: in the eastern part (Serbia), through river valleys to the north, and along the Adriatic coast to the northwest. The first evidence of a spread to the northwest was from southern Dalmatia on the Adriatic coast (Geroudet 1960; Tutman 1980; Griinhagen 1988) and to the north from the extreme south of Serbia (Vasic et al. 1980) (fig. 2). Up to 1980, the range extension in the eastern part of Yugoslavia included the discovery of breeding localities in southern and eastern Serbia, and in the western part new breeding localities in Herzegovina (Obratil 1976, 1982) (fig. 2).

Fig. 2. Breeding distribution of Red-rumped Swallow Hirundo daurica in Yugoslavia up to 1980. Dots show breeding records

Since 1980 (fig. 3), there has been further range extension, in eastern Yugoslavia in western Serbia (Marinkovic & Vuinovic 1986; Mikuska in litt) and in western Yugoslavia across the Adriatic coast up to the Italian frontier in Slovenia. Further new breeding localities were found on the Adriatic coast, in northern Dalmatia, showing northwesterly penetration from the former breeding range. In southern Dalmatia, the number of Red-rumped Swallows also increased. Only two new breeding localities were discovered on the part of the Adriatic coast between north Dalmatia and Istria, but previously we recorded the first nest in Istria in 1987 and soon after that discovered other new breeding localities in Istria (Stipcevic Notes 39

Fig. 3. Breeding distribution of Red-rumped Swallow Hirundo daurica in Yugoslavia up to 1990. Dots show breeding records

& Lukac in press). Recently, Red-rumped Swallows have also been discovered breeding in Slovenia (Ota 1989). By 1990, following this expansion, the breeding range of the Red- rumped Swallow in Yugoslavia covered southern, eastern and western Serbia, Herzegovina, Dalmatia, part of the Adriatic coast north from the Velebit mountain coastal area, central and eastern Istria and the southwestern part of Slovenia. Considerable range expansion is obvious since 1980 in the western part of Yugoslavia, and most recent discoveries of breeding localities reveal that this spread is still continuing. MAURTCIO STTPCEVIC and GORDAN LUKAC Marka Marulica 29, 57000 Zadar, Croatia, Yugoslavia; Faculty of Science, Department of Botany, Marulicev trg 20/11, 41000 Zagreb, Croatia, Yugoslavia

REFERENCES ANTAI., L., FF.RNBACH, J., MiKUSKA, J., PEU.E, I., & SZI.IVKA, L. 1971. Namenverzeichnis der Vogel der A. P. Vojvodina. lotus 23: 72-127. BERNHAUER, W. 1957. Ornithologische Beobachtungen an der Adriakiiste. Lams 9-10: 143- 148. DYMOND, J. N., FRASER, P. A., & GANTI.ETT, S. J. M. 1989. Rare Birds in Britain and Ireland. Gallon. GF.ROUDET, P. 1960. Observations de l'Hirondelle rousseline, Hirundo daurica, en Montenegro. Lams 12-13: 37-39. 40 Notes

GROSSMANN, E. 1910. Neue noch nicht nachgewiesene Vogel der Bocche di Cattaro, Omith. Jahrb. 21: 181-182, GRUNHAGEN, H. 1988. Rotelschwalbe (Cecropis daurica) Brutvogel in Mitteldalmatien. Die Vogelwelt 109: 38. MAKATSCH, W. 1950. Die Vogehtielt Macedoniens. Leipzig. MATVFJEV, S. D. 1957. Spreading of the Red-rumped Swallow. Aquila 63-64: 259, 329. MAMNKOVIC, S., & VuiNOVtc, D. 1986. Red-rumped Swallow: new breeding species of western Serbia. Lams 36-37: 327-328. OBRATII., S. 1976. New data for the Ornitofauna of Bosnia and Herzegovina. Glasnik zemaljskog muzeja 15: 215-219. 1982. The range of Red-rumped Swallow in Bosnia and Herzegovina. Glamik zemaljskog muzeja 21: 173-182. OTA, D. 1989. Breeding of Red-rumped Swallow Hirundo daurica in the Glinscica Valley near Trieste. Acrocephalus 39-40: 2-6. REISER, O. 1933. Mitteilung iiber Balkanvogel. J. Orn. 81: 366-370. ROHACEK, F. 1916. Ubersicht iiber die Brutvogel der Bocche di Cattaro. Omilh, jahrb. 27: 116- 129. STIPCEVIC, M., & LOKAC, G. In press. Survey of spreading and breeding range, changes of the Red-rumped Swallow in Yugoslavia. TUTMAN, 1. 1956. Observations of the Red-rumped Swallow, Hirundo daurica (L.) in Dubrovnik. Lams 8: 153-154. 1980. Comjmsition and dynamics of different bird populations of Dubrovnik region. PhD thesis, University of Sarajevo. VASIC, V. F., MATVEJF.V, S. D., & HAM, I. 1980. Present range of the Red-rumped Swallow, Hirundo daurica rufula Temra,, in SR Serbia and adjacent countries. Zbornik radova ofauni SR Srbije, SANU, Knjiga 1, pp. 85-100.

[This contribution was submitted in August 1990 and accepted for publication in November 1990. EDS]

Great Spotted Woodpecker apparently feeding on nectar On several occasions during June and July 1988, in a large garden next to woodland in Bergh Apton, Norfolk, I watched an adult female Great Spotted Woodpecker Dendrocopos major feeding at flowerheads of a red-hot-poker plant Kniphofia. She would perch upright on a flower stem below the flowerhead and deliberately insert her bill into the tubular florets, repeating this quickly while moving around the flowerhead. Having moved once around the flowerhead, selecting clusters of florets apparently at random, she would move on to another, usually visiting five to seven of the 11 flowerheads before moving off. On close inspection, a small drop of nectar was visible inside most florets, clusters of which around the flowerhead had been split open by the insertion of the woodpecker's bill, presumably to obtain this nectar. There did not seem to be enough insects present on the plant to justify the time spent by the woodpecker, and none could be seen inside any of the florets. The adult woodpecker was sometimes accompanied into the garden by a single juvenile; the latter occasionally perched briefly on the flower stems, but was never seen feeding at the flowerheads- in the way that the adult did. Between 1st and 22nd June 1989, a male and a female Great Spotted Woodpecker visited the same plant, always separately (plate 10). A total of 120 visits was recorded, with a peak of 16 on 15th June. D. LESTER Bell View, Hellington Comer, Bergh Apton, Norfolk NRI5 1BE Notes 41

10. Great Spotted Woodpecker Dendrocopos major feeding from floret of flowerhead of red-hot- poker Kmphofia, Norfolk, June 1989 (D. Lester)

Blue Tits as pollinators of the crown imperial At the end of April and the beginning of May in 1986, 1987 and 1988, in the University of Cambridge Botanic Garden, Cambridge, Blue Tits Parus caeruleus were regularly observed visiting flowers of crown imperials Fritillaria imperialis (plates 11-13). The tits repeatedly visited the large pendulous flowers throughout the day. Some of the flowers, especially those early in the season, were damaged by an unidentified species of finch (Fringillidae). The Blue Tits flew to the bare stems supporting the whorls of flowers and, by climbing these, introduced their heads into the corollas, apparently to probe one or more of the six large nectaries at the internal base of each petal. This procedure was repeated in up to seven flowers on different plants of the same clump before the tits flew to nearby trees. Visits were generally made by more than one tit at a time: usually two, but groups of 42 Notes

11-13. Blue Tits Parus caeruleus visiting flowers of crown imperials Fritillaria imperialis, Cambridgeshire, May 1988 (Alberto Burquez)

three or four were also observed. The tits were seen to be carrying pollen grains in their plumage. Flowers in clumps known to have been visited by Blue Tits set many fruits, while clumps in other parts of the garden where no visits were Notes 43 recorded had a zero fruit set. Accounts of Blue Tits visiting flowers are numerous (e.g. Ash 1959; Ash et al. 1961; England 1969; Soper 1969; Visik 1977; Ford 1985; Kay 1985). The 'fit' between the tit body and the flower suggests that this plant may be pollinated by birds in its native range in Turkey, Iran and Kashmir. These observations have been reported in more detail recently (Burquez 1989). Subsequently, Dr Martin Richards (in litt.) reported seeing Blue Tits visiting the flowers of crown imperials on two occasions in his Cambridgeshire garden, and Dr Spencer C. H. Barrett (verbally) reported Orchard/Northern Orioles Icterus spurius/galbula visiting crown imperial blooms in the garden of the University of Toronto, Ontario, Canada. ALBERTO BURQUEZ Centro de Ecologia, UN AM, Apartado Postal 1354, HermosiUo, Sonora 83000, Mexico REFERENCES ASH, J. S. 1959. Pollen contamination of birds. Brit. Birds 52: 424-426. , HOPE JONES, P., & MELVILLE, R. 1961. The contamination of birds with pollen and other substances. Brit. Birds 54; 93-100. BURQUEZ, A. 1989. Blue Tits, Parus caeruleus, as pollinators of the crown imperial, Fritillaria imperialis, in Britain. Oikos 55: 335-340. ENGLAND, M. D. 1969. Birds taking nectar. Brit. Birds 62: 288-289. FORD, H. A. 1985. Nectarivory and pollination by birds in southern Australia and Europe. Oikos 44: 127-131. KAY, Q. O. N. 1985. Nectar from willow catkins as a food source for blue tits. Bird Study 32: 40-44. SOPER, E. A. 1969. Birds taking honey. Brit. Birds 62: 200-201. VISIK, P. 1977. Blue Tits taking nectar. Brit. Birds 70: 548-549.