Notes

All Notes submitted to British Birds are subject to independent review, either by the Notes Panel or by the BB Editorial Board.Those considered appropriate for BB will be published either here or on our website (www.britishbirds.co.uk) subject to the availability of space. The breeding birds of and Skerry At the fringe of ’s northern and western soil base in the centre; Sea Mayweed Tripleuro- coastlines, an arc of remote forms some spermum maritimum is the dominant ground of the most important nurseries in the cover, along with pockets of Common Orache North Atlantic. The islands’ isolation combined Atriplex patula and Common Scurvygrass with frequent inclement weather means that Cochlearia officinalis. only small numbers of visitors have reached the The first detailed ornithological records for more inaccessible of the islands (and even fewer Sule Skerry date back to 1896, when James have actually managed to land there); yet most, Tomison began to document the birds encoun- if not all, will have been impressed by the abun- tered during his seven years as resident light- dant encountered. Since 1975, two of keeper (Tomison 1904). In 1901, Tomison these islands, Sule Skerry and Stack Skerry, to considered Common Guillemot Uria aalge to be the west of , have been the target of a uncommon and no Fulmars Fulmarus glacialis major seabird monitoring and ringing pro- were breeding, while the only Northern gramme that continues today. Gannets Morus bassanus (the species is hereafter referred to as ‘Gannet’) he encountered were Sule Skerry sick or injured birds. During the intervening Lying 56 km north of Whiten Head and 73 km years, there have been changes to both the northwest of Dunnet Head on mainland Scot- diversity and the populations of seabirds land’s north , Sule Skerry is one of Britain’s breeding on the . Common Guillemots most inaccessible and least-visited islands, and now number in excess of 7,000 pairs, while both home to one of the largest seabird colonies in Fulmar and Gannet are established breeding Scotland. The name ‘Sule’ is thought to derive species. Tomison recorded between six and ten from the Norse word Sula, meaning ‘Solan’ or pairs of Kittiwakes Rissa tridactyla, which had ‘Gannet’, or perhaps from the older name of increased to some 1,200 pairs in the 1970s and ‘Seal Skerry’ (the island is also home to large 80s but have since declined to fewer than 1,000 numbers of Grey Seals Halichoerus grypus) pairs. Other species were more numerous a (Tomison 1904). Sule Skerry covers just 14.2 ha century ago; for example, Black Guillemots (35 acres) and rises to a maximum height of Cepphus grylle bred regularly then but ceased to 15 m above the high-water mark. This rocky breed in the mid 1980s. outcrop comprises banded gneiss with a shallow Today, Sule Skerry is a particularly impor- tant breeding site for Puffins Fratercula arctica and sup- ports approximately 10% of the entire British and Irish population (Mitchell et al. 2004). Other breeding seabirds include European Storm-petrel Hydrobates pelagicus, Shag Phalacro- corax aristotelis, Great Skua Stercorarius skua and Razor- bill Alca torda (see table 1); a small colony of Gannets has become established in recent years and it seems likely that

John Love numbers will increase. 132. An aerial view of Sule Skerry, May 2005. Other breeding species

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Table 1. Estimated numbers of breeding pairs of seabirds on Sule Skerry recorded during visits by the Sule Skerry Ringing Group in 1975, 1986, 1993 and 2005. Note that Shag Phalacrocorax aristotelis experienced a significant failure in 2005, and only six pairs were located. 1975 1986 1993 2005 Fulmar Fulmarus glacialis 43 173 346 314 European Storm-petrel Hydrobates pelagicus <1000a 200–500b 400b 450c Northern Gannet Morus bassanus 00077 Shag Phalacrocorax aristotelis 430 874 701 6d Great Skua Stercorarius skua 0012 Herring Gull Larus argentatus 48 30 30 20–25 Greater Black-backed Gull Larus marinus 14 22 22 15–20 Kittiwake Rissa tridactyla 1,163 973 710 c. 500 Arctic Tern Sterna paradisaea 175 100+ <100 0 Common Guillemot Uria aalge – 3,462 7,178 – Razorbill Alca torda – 40 75 <50 Black Guillemot Cepphus grylle 3100 Puffin Fratercula arctica 44,289 42,456 – 34,348

Key: a using observations b using ringing activity c using echolocation d possibly due to poor winter weather conditions include Common Eider Somateria mollissima, and a handful of other species. Expeditions by Oystercatcher Haematopus ostralegus,Rock the Sule Skerry Ringing Group (SSRG) began in Pipit Anthus petrosus, Common Starling 1975, when the BTO encouraged ringers to Sturnus vulgaris and, occasionally, Northern focus on seabirds, particularly auks, which until Wheatear Oenanthe oenanthe.Leach’s Storm- that time were under-represented in terms of petrels Oceanodroma leucorhoa have not been the numbers being ringed in Britain. The SSRG confirmed as breeding on the island, but there established a programme of organised and sys- was a reported breeding record in 1933 tematic ringing, collecting data in accordance (Robinson 1934), and a pair was killed at the with the BTO’s Scientific Strategy, which in 1908 (Robinson 1930). demands a methodical programme of ringing and recaptures to generate recoveries for moni- Stack Skerry toring movements and survival. Stack Skerry (or ) is situated 8 km While attempting to meet these aims, the southwest of Sule Skerry and is home to an SSRG has identified other specific priorities important Gannet colony. It is divided into two which now form a part of the ongoing pro- halves, each rising to 40 m at the highest point gramme: and together covering approximately 2.5 ha • monitoring Puffin burrows to estimate (6 acres). This island is undoubtedly one of the breeding population, density, breeding most remote locations in Britain and very few success and condition of chicks before (and landings have been made owing to the constant after) fledging; swell and hazardous rocks (Fisher & Vevers • monitoring the Gannet colony, established 1943). The numbers and species diversity of in 2003, and assessing breeding success, site seabirds on Stack Skerry are considerably lower fidelity, colony expansion and possible inter- than those on Sule Skerry. Apart from Gannets, specific competition with other seabirds; it currently holds breeding populations of Shag, • increasing the personnel available to con- Kittiwake, Common Guillemot and Razorbill. tinue long-term seabird studies on the island by training in ringing and monitoring tech- Bird ringing on Sule Skerry and Stack Skerry niques; Owing to its inaccessibility, relatively few birds • collecting data on other birds, cetaceans and were ringed on Sule Skerry before 1975. In invertebrates on the island. 1935, H. W. Robinson ringed at least 100 Arctic The SSRG has made several attempts to land Terns Sterna paradisaea; in 1949, Ian Pennie on Stack Skerry during the last 30 years but has ringed at least 17 Shags; and, in 1967 and 1968, been thwarted by a combination of inclement Dave Stark and Jim Williams ringed 150 Puffins weather and unco-operative fishermen. In 2002,

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Gannets being ringed, from which there have been five local recoveries. Puffin ringing and recap- ture data from the past 30 years comprise more than 100,000 ringed birds and over 17,000 recaptures. This unique dataset will enable the group to monitor annual and long-term fluctuations in breeding success and sur- vival rates of both adults and chicks. This is particu- larly important at a time Stuart Newson when sea temperatures are 133. For many years, the Sule Skerry Ringing Group had made use of a 110-year-old double-walled shed that was erected originally for workmen rising, fish stocks are building the lighthouse for Charles and David Stevenson in 1892–94.This declining and widespread woodworm-ridden structure was destroyed by gales in early 2005, but breeding failures of several fortunately it has since been possible for the Group to use a newer seabird species are being building as base camp, seen here to the left of the lighthouse. reported throughout the however, an enthusiastic and experienced . boatman, with a biological background and a genuine interest in conservation, was recruited Population estimates and movements and this significantly improved the chances of Puffin landing on the island. Aided by good weather, Estimates of the size of the Puffin colony on the first successful landing by a small survey Sule Skerry have varied widely over the years. and ringing party was made in July 2002. In this Based on visual observations, Stark (1967) esti- year, 94 Gannet chicks were ringed on the South mated the colony to contain c. 60,000 breeding Rock from approximately 100 pairs breeding pairs. In 1975, SSRG employed random-quadrat there; one of the ringed birds subsequently techniques to count the number of burrows became a victim of the MV Prestige oil spill in within set areas and estimated the population to northeast Spain the following December. In be 44,289 breeding pairs. A comparable (and 2003, over 1,100 Gannet chicks were ringed and independent) estimate was obtained in 1998 by two have subsequently been recovered from using a number of linear-transect burrow Portugal. A landing in 2005 resulted in 824 counts. Observations since the 1970s suggest that numbers have declined slightly over the last 30 years, and the potential breeding population is con- sidered to be between 30,000 and 40,000 pairs. Considering the number of Puffins that have been ringed since 1975, there have been relatively few recov- eries, most being dead birds washed up on in Scotland and the Mediter- ranean. There have been just 17 recaptures of Puffins on Sule Skerry that were ringed Jez Blackburn away from the island, and 134. Puffins Fratercula arctica on Sule Skerry, one of the island’s most important breeding seabird species. only seven Sule Skerry birds

302 British Birds 100 • May 2007 • 300–308 Notes have been found at other British colonies. The Currently, much of the colony is to be found Prestige oil spill in December 2003 resulted in on the North Rock, where birds breed in a recovery of 11 Sule Skerry-ringed Puffins, while densely packed colony on areas of flat rock. The 29 have been either shot or killed in the Faeroe South Rock currently houses just 110 pairs, Islands. In 2005, six birds that had originally however, and there is ample scope for the been marked in 1975 were caught or found colony to expand here. Future surveys will dead, one of which had not previously been assess changes in numbers and extent of the recaptured during any of the 17 intervening colony. expeditions. The longevity record for Recoveries of Gannets ringed on Stack Puffin on Sule Skerry now stands at 30 years Skerry will compliment current studies of and eight days, just eight days short of the Gannets ringed elsewhere in Britain. Ringing current national longevity record. will also provide information on survival and inter-colony movements and may be able to Gannet identify the origins of birds that are affected by Early records suggest that Gannets were environmental incidents such as oil spills and breeding on Stack Skerry as early as 1710 storm ‘wrecks’, highlighting the impact of such (Gurney 1914), but it was not until 1890 that events on this particular colony or the popula- the first estimate recorded 3,500 pairs (Fisher & tion as a whole (Grantham 2004). Vevers 1943). Further counts in 1904 and 1914 revealed a population in excess of 4,000 pairs Acknowledgments (Fisher & Vevers 1944) and Wynne Edwards et The success of each expedition relies on teamwork and the specialist skills and attributes of a great many people, al. (1936) estimated the population to be 8,000, who are too numerous to mention individually here. We although it is not entirely clear whether these would, however, like to thank Bob Anderson and Angus estimates referred to individual birds, nests or Budge, skipper and second mate of the MV Halton, whose pairs. Malcolm Stewart, who landed on the expertise in safely getting people on and off these islands was essential to the ultimate success of these expeditions. northern half of the island in July 1937, esti- The group is also grateful to SNH and the Northern mated 3,500 pairs (Stark 1967) and when only Lighthouse Board for permission to access the islands. 2,010 pairs were found in 1949 (Williamson & References Boswall 1960), fears of a significant decline were Fisher, J., & Vevers, H. G. 1943.The breeding distribution, confirmed. The cause of this decline and the history and population of the North Atlantic Gannet reasons for its subsequent turnaround remain (Sula bassana) – Part 1. A history of the Gannet’s unknown. James Fisher and W. J. Eggeling colonies and the census in 1939. J.Anim. Ecol. 12: found 2,800 pairs in 1960 (Williamson & 173–213. — & — 1944.The breeding distribution, history and Boswall 1960), suggesting that numbers were population of the North Atlantic Gannet (Sula bassana) already starting to recover. The highest count – Part 2.The changes in the world numbers of the made during the last 30 years was in 1985, when Gannet in a century. J.Anim. Ecol. 13: 49–62. 5,900 nests were recorded, although this figure was derived from ‘moderate- quality photographs’ (Mitchell et al. 2004), so the accuracy is open to ques- tion. More recently, aerial counts revealed 4,888 nests in 1994 (Murray & Wanless 1997) and 4,618 nests in 2004 (Wanless et al. 2005). In 2005, a survey employing a combination of video footage and photographs, supported by counts from boat- and ground-based observers, estimated 3,600 ± Jez Blackburn 135. The Morus bassanus colony on Stack Skerry, 300 nests. with MV Halton in the background, July 2005.

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Grantham, M. J. 2004. Age structure and origins of British & Orkney. Ann. Scot. Nat. Hist. 1934: 93. Irish Guillemots Uria aalge recovered in recent Stark, D. 1967. A visit to Stack Skerry and Sule Skerry. European oil spills. Atlantic Seabirds 6(3): 95–108. Scot. Birds 4: 548–553. Gurney, J. H. 1914.The Gannetry at ‘The Stack’, Orkney Tomison,J. 1904. Sule Skerry, Orkney, and its bird-life. The Islands. Ibis 2 (4): 631–634. Annals of Scottish Natural History 1904: 16–26. Mitchell, P.I., Newton, S. F., Ratcliffe, N., & Dunn,T. E. 2004. Wanless, S., Murray, S., & Harris, M. P.2005.The status of Seabird Populations of Britain and Ireland.T. & A. D. Northern Gannet in Britain & Ireland in 2003/2004. Poyser, London. Brit. Birds 98: 280–294. Murray, S., & Wanless, S. 1997.The status of the Gannet in Williamson, K., & Boswall, J. 1960. A landing on Sule Stack. Scotland in 1994–95. Scot. Birds 19: 10–27. Scot. Birds 1: 266–268. Robinson, H.W. 1930. Leach’s Fork-tailed Petrel in Orkney. Wynne Edwards,V. C., Lockley, R. M., & Morrey Salmon, H. Ann. Scot. Nat. Hist. 1930: 22. 1936.The distribution and numbers of breeding — 1934. First nesting of Leach’s Fork-tailed Petrel in Gannet. Brit. Birds 29: 262–276. Jez Blackburn, c/o BTO, The Nunnery, Thetford, Norfolk IP24 2PU Adrian Blackburn, ‘Suleska’, 1 Richmond Road, Retford, Nottinghamshire DN22 6SJ Dave Budworth, 121 Wood Lane, Newhall, Swadlincote, Derbyshire DE11 0LX

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Recovery of Peregrine Falcon after hitting the sea On 24th June 2006, I was leading a group of as a ‘butterfly stroke’, using her wings in vig- naturalists along the coast path on the east cliffs orous flapping motions to propel herself across of Portland, Dorset, near Southwell village. The the sea. She was soon joined by two of her resident pair of Peregrine Falcons Falco pere- recently fledged young, which circled around grinus was pursuing Feral Pigeons Columba her, calling constantly. It was not clear whether livia over the sea, and we watched the Pere- they were distressed at the sight of their mother grines for about 30 minutes, during which time in trouble, or were just begging for the pigeon three or four separate pigeon flocks were they had watched her catch. The male, which attacked. The falcons’ tactics involved the male had been nearby during the hunt, was now making repeated stoops at a flock until one nowhere to be seen, and did not pigeon was separated from the rest. This reappear during the next 30 minutes while we unlucky bird would then be pursued by the watched the drama unfold. female until both were over the coast, when the It took the female Peregrine about 20 Peregrine would attempt a kill without risk of minutes to reach the shoreline, her journey losing the pigeon in the sea. Each pursuit that being significantly lengthened by the current, we watched resulted in the pigeon managing to which moved her south along the coast towards get away, with one bird flying at full speed Portland Bill. Unfortunately, the last few metres underneath a boulder to escape its pursuer. were hidden from our view behind the next After several unsuccessful attacks, the female , but we assumed that she climbed a attempted to catch a particularly slow-flying rock on the shoreline and dried off in the hot pigeon while still over the sea. The pigeon was sun. The coast here is composed of large lime- hit in flight and grasped by the female, while stone boulders from previous quarrying and the male circled high overhead. However, with -falls, so the bird would have been able to the pigeon firmly in her talons, the female failed climb out of the sea. As we left the site, we found to recover fully from her dive and clipped the that the two youngsters had returned to their surface of the sea. At first, it appeared that she usual ledge; presumably the female had not would be able to continue flying low over the managed to hang on to the pigeon during the sea, but it then became apparent that she was swim ashore, although perhaps she did so ini- too heavy to continue, and had to land on the tially, which might explain why she did not sea surface. For a few seconds she floated, wings immediately take off again from the surface? outstretched, and then started ‘swimming’, Ratcliffe (1993) stated that ‘Peregrines occasion- making a slow and laborious journey across the ally pick prey from water, when they have chased 300 m or so of sea back to the rocks on the it in, or when it is wounded, and they will also coast. She employed what can best be described retrieve kills which have fallen into the water.’

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The following morning, we returned to see if their usual perches and the two youngsters were there was any sign of the unfortunate female. soaring above the cliffs some distance away; all Unlike the previous day, which had been hot four birds appeared fit and well. I checked them and sunny, there was constant light rain. We again four weeks after the original incident and soon found the male Peregrine, sheltering on a found both adults with one young still with cliff ledge; further along, we found the female, them. The female was not seen hunting, perched on another cliff ledge, facing inwards although the male was observed passing food to with her wings spread. Rainwater running off her on the cliff, and once again was observed to the cliff was showering over her plumage, which hold her wings out when it started raining. she dried occasionally with a vigorous shake. It was tempting to think that this was a deliberate Reference activity to wash the salt from her plumage. Ratcliffe, D. A. 1993. The Peregrine Falcon. 2nd edn. Poyser, Three days later, both adults were occupying London. Bob Ford Nature Portfolio Image Library, PO Box 4439, Portland, Dorset DT5 1YT

Peregrine Falcons nesting in central London Peregrine Falcons Falco peregrinus are now site. The nestbox was resolutely ignored by the nesting in central London on a regular basis for Peregrines when they returned in early 2004, the first time since reliable records began. The however, and instead they made a scrape in original population on the south coast was some pea shingle which had been scattered in wiped out in the population crash of the 1960s the open area adjacent to the nestbox. This time but, during the 30 years that it took it to the birds were successful and the first of two recover, there was an unprecedented increase in chicks fledged on 14th June. Afterwards, the the size and scale of new buildings in urban nestbox was modified by removing an incon- areas. Thus, having reached the cliffs of Kent, venient entrance ‘step’ and opening up one of Peregrines discovered that completely new suit- its sides. able nest-sites were available on power stations In March 2005, the central London birds had close to the River Thames. Sightings farther up left the Regent’s Park area and selected a new the river soon began to increase and, in 1996, site on a tall residential building about 4 km birds were found to be roosting on the tower- away, close to the City. On 30th March, it was like chimney of the disused Bankside power established that one egg had been laid (on bare station, which was then being converted into concrete) and sightings of the female on the the Tate Modern art gallery. nest ledge continued for at least two more days. In 2001, breeding was recorded in the inner From our high-level vantage point, it was pos- London area for the first time when Peregrines sible to observe all the nesting and roosting raised three young at Battersea power station, places in the central London area, and on 3rd about 5 km southwest of the City; in the same April the birds were prospecting an alternative year, another pair frequented the Millennium ledge on the roof of the Old Bailey, less than 1 Dome, a similar distance to the east, although km away. Here, a nest scrape was made in a this site, like the Tate Modern, has proved to be tangle of waste rope and rubber matting, unsuitable for breeding owing to the lack of jammed precariously into a crevice at the edge suitable flat ledges. It was only a matter of time of the roof, a choice of nesting material which before a site in central London itself was occu- does not appear to have been previously pied and, on 19th March 2003, a pair was seen recorded. The female’s behaviour immediately roosting on a public building near Baker Street. suggested that further laying was about to take During the next five days, the birds were seen place; by 5th April she was almost certainly mating on a residential tower block near incubating and this was confirmed on 8th when Regent’s Park and by 25th March the female was nest reliefs were seen twice. It was impossible almost certainly incubating at that site. (see plate 136) to count the eggs but it seems This first attempt failed (for reasons clear from the dates that they must have formed unknown) and once the birds had departed, a the remainder of the clutch which had so nestbox was installed to improve shelter at the recently been started at the nearby City site. For

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It is interesting to note that although many Peregrines are now nesting on man-made struc- tures, comparatively few are doing so in such close proximity to human habitation as the London birds, at both the Regent’s Park and the City sites. Another intriguing aspect of their behaviour has been the regular use of the Tate Modern, for roosting, hunting and display/mating, regardless of the distance from the various nesting sites, up to 4 km away. Detailed observations were made of these central London Peregrines, notably during their

David C. Johnson breeding attempts at the Regent’s Park site, and 136. Female Peregrine Falcon Falco peregrinus, Old we hope to publish this information in full in Bailey, central London,April 2005.The nest scrape lay among waste rope and other man-made materials. due course. In view of the fact that a number of pairs are now nesting in major cities worldwide, three more days, incubation proceeded nor- including New York and Chicago in the USA, mally, but on 12th April the female was found some thought has been given as to how many lingering near the nest-site, which had become may ultimately settle in central London. The accidentally dislodged and destroyed. The fol- area which lies within the Underground Circle lowing day, both birds were back at the Regent’s Line and immediately adjacent to it covers Park (2004) site, showing all the signs that they approximately 50 km2 and since Ratcliffe (1993) would make yet another attempt. Since a suggested that a density of 3–4 pairs per 100 webcam had been installed here in anticipation km2 is possible, then two pairs might be of further nesting, this was a particularly expected. There are, however, signs that a higher welcome and unexpected development. On density may occur. During 2006, a new (single) about 26th April, the first of three eggs was duly bird was seen to be occupying the Regent’s Park laid in the modified nestbox and the birds site on an occasional basis, unchallenged by the became stars of the 2005 BBC ‘Springwatch’ established pair at the City site 4 km away. In television programme. All three hatched suc- coastal areas, where conditions are favourable, cessfully and the first of three young birds spacing of only 2 km between nests is found not fledged on 13th July. infrequently (pers. obs.). In an urban area such Although the 2006 season started with one as this, there is no shortage of nest-sites or prey, bird regularly visiting the Regent’s Park site, by chiefly Feral Pigeons Columba livia, and it mid February both adults were again fre- seems quite likely that more than two pairs may quenting their 2005 City tower block, where ultimately nest in the central area, with a sub- some fresh pea shingle had probably made the stantially greater number in Greater London as site more attractive. By virtue of 1,000+ hours a whole. of observations, we were confident that the same individuals formed the pair for a fourth Acknowledgments consecutive year. The female had finer than Special thanks are due to Dick Treleaven, Ian Newton,Tony Duckett, Gina Johnson, Dave Morrison, Stuart Harrington, usual streaking on the upper breast, while the Des McKenzie, Andy Fisher and Dave Flint for their help in male could be distinguished by a combination various ways. We would also like to thank the RSPB for of a brilliant-white breast and strikingly help with travel arrangements, while this study would not orange-yellow legs and cere; these characteris- have been possible without the help and co-operation of all those responsible for permitting access to strategically tics helped us to track these individuals between placed rooftops. the various nest-sites. In early March, they were seen displaying and mating at the Tate Modern Reference and once again they nested successfully, the first Ratcliffe, D. A. 1993. The Peregrine Falcon. 2nd edn. Poyser, of three chicks fledging on 12th June. London. David C. Johnson ‘Nursery Lodge’, Inner Circle, Regent’s Park, London NW1 4NY; e-mail [email protected] Denis Corley Ty Coch, 19B Queens Road, Weybridge, Surrey KT13 9QE; e-mail [email protected]

306 British Birds 100 • May 2007 • 300–308 Notes Peregrine Falcon retrieving prey from flock of Carrion Crows On 13th January 2005, on the saltmarsh just began pulling the Peregrine Falcon’s tail as west of Wigtown, Dumfries & Galloway, I wit- another pulled hard on the gull’s outstretched nessed an intriguing example of Peregrine wing. This had the effect of dislodging the falcon Falcon Falco peregrinus behaviour when an completely and forced it to move sideways. immature female Peregrine was confronted by a Throughout the whole encounter I had the flock of 18 Carrion Crows Corvus corone which impression that the Peregrine was wet and tired; was attempting to ‘steal’ the raptor’s recently I anticipated that it would relinquish the prey seized prey. entirely under the weight of such intimidation The Peregrine was stooped over an unplucked and this seemed to be confirmed when one of gull, probably a Black-headed Gull Larus ridi- the crows itself began to pluck the gull. Within bundus, but was increasingly intimidated by the seconds, however, the Peregrine took off and ever more bold behaviour of the crows. Initially, seemed to fly away from the crow flock, but as it it attempted to shield the prey with an outspread did so it was instantly pursued by seven or eight wing and twisted the prey with a single foot, so crows. The Peregrine then swung round over the that it could face the majority of the encircling crows remaining on the ground, passing them flock. Although the Peregrine made several several times and once making a swoop as if to attempts to pluck its victim, it was almost pre- strike. Soon all the corvids were airborne and, vented from doing so by the crows manoeuvring while vocalising in alarm, began to fly away from so tightly around it. Within a short while, it was the vicinity of the gull. Eventually they all disap- completely encircled and stressed by the other peared, at which point the Peregrine landed on birds’ threatening gestures. In a final effort to its prey and resumed plucking in solitude. retain control, the falcon spread both wings to I discussed the incident with the late Derek cowl the prey, while dragging it away slightly Ratcliffe prior to his death, and he suggested under the grip of a single foot. With the falcon that he had never encountered a comparable momentarily unbalanced, one Carrion Crow example of this behaviour. Mark Cocker The Hollies, The Street, Claxton, Norwich NR14 7AA

Mixed singing in Phylloscopus warblers Following Gordon Hopkins’s note on a Willow sometimes began its song with Chiffchaff-like Warbler with an unusual song (Brit. Birds 99: notes and ended it with Willow Warbler-like ones 580), I was reminded of two similar individuals I and sometimes vice versa. Unfortunately, both have encountered recently in Leicestershire. On birds were singing from dense hawthorn 3rd May 2004, I heard a Phylloscopus warbler Crataegus monogyna scrub and were not seen suf- singing at Stoughton Airfield which began with ficiently well to confirm their identification as approximately six to eight notes of Common either Chiffchaff or Willow Warbler. Chiffchaff Ph. collybita song and then finished In addition, the Leicestershire and Rutland Bird with the typical descending notes of a Willow Report for 2002 makes reference to a Common Warbler Ph. trochilus. This bird sang almost con- Chiffchaff at Pickworth Great Wood on June 1st stantly for a period of ten minutes using this dis- 2002 which had ‘an aberrant song, ending more tinctive series of notes. On 19th June 2005, I heard like a Willow Warbler’, while a similar mixed a similar song on allotments in the Aylestone Park singer (which remained unidentified) was area of Leicester; this time, however, the bird reported at Thurnby during the summer of 2005. Rob Fray 5 New Park Road, Aylestone, Leicester LE2 8AW; e-mail [email protected]

The note by Hopkins (2006) on a Willow extended review of mixed singing in European Warbler singing its own song followed immedi- passerines by Helb et al. (1985). The latter ately by several notes of the song of Common defined mixed singers as birds ‘which in their Chiffchaff reminded me of a similar observation full song extensively copy vocal patterns of one that I made in 1985 in Germany and of the alien species’; the alien song may be produced

British Birds 100 • May 2007 • 300–308 307 Notes alternately with the bird’s own song, or frag- Lille 1988). Indeed, for most records, plumage ments of both songs are combined into a single features of mixed-singing Phylloscopus warblers phrase. Mixed singing has been recorded among indicate that the birds are Willow Warblers. It is many European passerines and is most wide- understood that mixed singing results from a spread in Eurasian Treecreeper Certhia familiaris defect in normal song learning, particularly in (reproducing Short-toed Treecreeper’s C. cases when the copying species is rare and young brachydactyla song) and Thrush Nightingale birds learn erroneously from the more common Luscinia luscinia (singing the song of Common copied species (Helb et al. 1985; Baptista & Nightingale L. megarhynchos). Baker & Boylan Kroodsma 2001). (1999) reported frequent mixed singing in a population of Lazuli Buntings Passerina Acknowledgment amoena, Indigo Buntings P. cyanea and hybrids I am grateful to Christine Alder of the BirdLife International library in Cambridge for helping to access between the two in Wyoming, USA. Several references. more cases of mixed singers reproducing the songs of Willow Warbler and Common Chif- References fchaff have been reported (for an overview see Baker, M. C., & Boylan, J.T. 1999. Singing behavior, mating Helb et al. 1985; see also above and two associations and reproductive success in a population of hybridizing Lazuli and Indigo Buntings. Condor 101: instances reported in the Cambridgeshire Bird 493–504. Report: 2002 (p. 101) and 2004 (p. 128)). They Baptista, L. F., & Kroodsma, D. E. 2001. Avian Bioacoustics. remain scarce, however, unlike the high propor- In: Handbook of the Birds of the World.Vol. 6. Lynx tion of mixed singers in some populations of Edicions, Barcelona: 10–52. Helb, H.-W., Dowsett-Lemaire, F., Bergmann, H.-H., & Eurasian Treecreepers and Thrush Nightingales Conrads, K. 1985. Mixed singing in European songbirds (Thielcke 1986; Lille 1988). Although hybrids – a review. Zeitschrift für Tierpsychologie 69: 27–41. between Willow Warbler and Chiffchaff have Hopkins, G. R. 2006. Unusual song of Willow Warbler. Brit. Birds 99: 580. been assumed in some cases, it is more likely Lille, R. 1988. Art- und Mischgesang von Nachtigall und that most (or indeed all?) of those birds belong Sprosser (Luscinia megarhynchos, L. luscinia). Journal für to one species, as has been shown for mixed- Ornithologie 129: 133–159. Thielcke, G. 1986. Constant proportions of mixed singers singing Eurasian Treecreepers and Thrush in Tree Creeper populations (Certhia familiaris). Ethology Nightingales (Helb et al. 1985; Thielcke 1986; 72: 154–164. Peter Herkenrath UNEP World Conservation Monitoring Centre, 219 Huntingdon Road, Cambridge CB3 0DL

EDITORIAL COMMENT We shall not publish any further individual notes on this behaviour in Phylloscopus warblers unless they relate to particularly unusual circumstances.

Hawfinches eating snow During 25th–29th December 2005, up to three watched a male Hawfinch picking and eating Hawfinches Coccothraustes coccothraustes visited snowflakes from the tree branches. That they a garden on the southern edge of Milton Keynes, were pecking at the snow and not buds on the Buckinghamshire. They fed almost exclusively branches was confirmed when one male flew on the seeds of an Ash Fraxinus excelsior tree but onto a wooden fence and continued to eat the did occasionally take seeds (principally sun- snowflakes, which encrusted round its bill with flower seeds and peanuts) from a bird feeder the cold. It was evidently melting the snow in its and from the ground below the feeder. mouth to drink. BWP does not mention this On 26th December, snow fell to a depth of resort to snow as a water source to assist seed 2–3 cm and on three separate occasions I digestion. Ian Packer Waterfallows Farmhouse, Waterfallows Lane, Linton Heath, Swadlincote, Derbyshire DE12 6PF

EDITORIAL COMMENT Ian Newton has commented that he has observed several species of finches eating snow in an outdoor aviary, and that the behaviour is probably not uncommon during snowfall, but it appears not to have been recorded previously.

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