Notes. Does the Honey-buzzard feed during migration?

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1 Martin Coath 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 ( subject to the availability of space. On 14th May 2005, I was shown the nest of a Greylag Goose Anser anser in a pine Pinus tree in Kent. I was able to observe the nest from a window in a first-floor flat in Brasted, adjacent to the busy A25, looking 40 m across communal 176. Nest-site of Greylag Goose Anser anser, Brasted, Kent, May Martin Coath 77 Oakhill Road, Sevenoaks, Kent TN13 1NU Greylag Goose nesting in pine tree grounds to the 20-m-high tree. The goose was sitting along a branch of the pine, only about 1 2 m from the top (plate 176). It was impossible to see what was under the sitting bird, and there was no sign of an old nest, but I assume that there must have been some sort of platform for the goose to lay on/in. The nearest water to the site is 1 km to the northwest. On 20th May, the parent bird flew down to the lawn and honked encouragement at the young. They immediately left the nest one after the other, bouncing down through the branches; five of the six survived. The young became separated from the parent in the enclosed grounds, and were eventually gathered up and transported to Sevenoaks Wildfowl Reserve. BWP states: [nest] on ground, often sheltered hollow, or at base of tree, under bush or in reedbed, also on rafts of vegetation in rivers of 463 nests in Czechoslovakia 19.7% in pollarded willows (Salix) rarely more than 10 m from water and then only on islands. Eddie Chapman (in litt.) has commented that there are records from Norway and other European countries of Greylags nesting in pines. There have been other records in BB concerning Greylag Geese nesting in trees (for example Brit. Birds 95: 189), but this seems an extraordinary nest-site. Does the Honey-buzzard feed during migration? There are two distinct feeding strategies among long-distance migrant raptors: some species hunt during their migration, while others store fat before migrating. In the latter group, individuals require fat deposition amounting to 15 25% of lean body mass for their migration (Gessaman 1979; Candler & Kennedy 1995; Smith et al. 1986). Some authors suggest that, in soaring raptors like the Honey-buzzard Pernis apivorus, weight loss during migration optimises the use of thermal currents (Brown quoted by Gensbøl 1992). Conversely, raptors which use mostly powered flight (e.g. Osprey Pandion haliaetus, kites Milvus and harriers Circus) usually feed during migration (Cramp & Simmons 1980; Kerlinger 1989; Gensbøl 1992; Blanco 1994, 1997; Yosef 1996; Alerstam & Hedenström 1998). Smith et al. (1986) estimated that although 100 g of fat would sustain a soaring Broad-winged Hawk Buteo platypterus for more than 20 days, powered flight would exhaust this fuel reserve in less than five days. British Birds 99 July

2 In the central Mediterranean region, several species of Accipitriformes are regularly observed feeding during both spring and autumn migration. In particular, Black Kites M. migrans, Marsh C. aeruginosus, Montagu s C. pygargus and Pallid Harriers C. macrourus were observed hunting over many small islands at the Strait of Messina and other sites in Italy (Giordano et al. 1995; Agostini & Logozzo 1998; Agostini & Panuccio 2003; Pandolfi & Sonet 2003; Panuccio et al. 2004; Premuda et al. 2004; pers. obs.). Among soaring raptors, Short-toed Eagles Circaetus gallicus were observed hunting over the island of Marettimo during autumn migration (Agostini pers. obs.). In the case of the Honey-buzzard, birds are regularly seen drinking while on migration in the Middle East, although at present there is no evidence that this species feeds during migration (Gensbøl 1992; Yosef 1996; Hake et al. 2003). Passage of Honey-buzzards along the Calabrian Apennines, southern continental Italy, is well documented (see Agostini & Logozzo 1997). In autumn 2005, 3,458 Honey-buzzards were noted between 24th August and 12th September Close observations revealed that 15 birds showed a full crop and, of these, 11 were adults. Nine of the 15 (60%) were observed on 26th August. Two individuals with distended crops were photographed (plate 177). Only those individuals that were extremely close (<100 m) could be checked with confidence, so many others with a full crop may have passed undetected. Visual observation of crop distension is evidence of recent food ingestion (Shelley & Benz 1985; Pandolfi & Sonet 2003), so we suggest that hungry or opportunistic Honey-buzzards occasionally feed during migration, even if the majority fast in an attempt to minimise migration time and optimise the use of thermal currents. It is interesting to note that during observations at Hawk Mountain Sanctuary (Pennsylvania, USA), Shelley & Benz (1985) reported 8% of 623 Broad-winged Hawks with distended crops and 25 individuals in active hunting. Notes 177. Honey-buzzard Pernis apivorus with distended crop, Calabrian Apennines, southern Italy, August Acknowledgments We wish to thank Elena Grasso, Patricia Molina and Michael Dech for their help during observations. Agostini, N., & Logozzo, D Autumn migration of Accipitriformes through Italy en route to Africa. Avocetta 21: & Primi dati sulla migrazione primaverile dei rapaci Accipitriformi sull isola di Marettimo (Egadi). Riv. Ital. Orn. 68: & Panuccio, M How do Accipitriformes behave during autumn migration at the Circeo Promontory (Central Italy)? Riv. Ital. Orn. 73: Alerstam,T., & Hedenström, A The development of bird migration theory. J. Avian Biol. 29: Blanco, G Seasonal abundance of Black Kites associated with the rubbish dump of Madrid, Spain. J. Raptor Res. 28: Role of refuse as food for migrant, floater and breeding Black Kites (Milvus migrans). J. Raptor Res. 31: Candler, G. L., & Kennedy, P Flight strategies of migrating Osprey: fasting vs. foraging. J. Raptor Res. 29: Cramp, S., & Simmons, K. E. L The Birds of the Western Palearctic.Vol. II. Oxford University Press, Oxford. Gensbøl, B Guida ai rapaci diurni d Europa, Nord Africa e Medio Oriente. Zanichelli, Bologna. Gessaman, J. A Premigratory fat in the American Kestrel. Wilson Bull. 91: Giordano, A., Hein, C., Ricciardi, D., Davani, S., Bellomo, M., & Irrora, A Primi dati sull attività alimentari dei rapaci in transito sullo Stretto di Messina durante la migrazione primaverile ( ). In: Pandolfi, M., & Foschi, U. (eds.), Suppl. Ric. Biol. Selvaggina 22: Hake, M., Kjellén, N., & Alerstam,T Age-dependent migration strategy in honey buzzards Pernis apivorus tracked by satellite. Oikos 103: Kerlinger, P Flight Strategies of Migrating Hawks. Univ. Chicago Press, Chicago. Michele Panuccio 366 British Birds 99 July

3 Pandolfi, M., & Sonet, L Migrazione di rapaci lungo la costa adriatica (Parco Naturale San Bartolo, ). Fenologia e comportamento delle specie del genere Circus. Avocetta 27: Panuccio, M., Polini, N., Forconi, P., Fusari, M., Giorgetti, G., Marini, G., & Agostini, N Mount Capodarco: a survey on the migratory behaviour of Accipitriformes along the Adriatic coast of central Italy. Riv. Ital. Orn. 74: Premuda, G., Mellone, U., & Cocchi, L Osservazioni sulle modalità della migrazione primaverile dei rapaci a Capo d Otranto. Avocetta 28: Shelley, E., & Benz, S Observation of aerial hunting, food carrying and crop size of migrant raptors. In: Newton, I., & Chancellor, R. D. (eds.), Conservation Studies on Raptors: ICBP Technical Publication No. 5, Cambridge. Smith, N. G., Goldstein, D. L., & Bartholomew, G. A Is long-distance migration possible for soaring hawks using only stored fat? Auk 103: Yosef, R Raptors feeding on migration at Eilat, Israel: opportunistic behaviour or migratory strategy? J. Raptor Res. 30: Michele Panuccio, Nicolantonio Agostini, Stephen Wilson, Giuseppe Lucia, Jack Ashton-Booth, Gianpasquale Chiatante, Ugo Mellone and Simone Todisco MEDRAPTORS (Mediterranean Raptor Migration Network, Via Mario Fioretti, Rome, Italy; medraptors@raptormigration.org Michele Panuccio Comments on the roosting behaviour of Marsh Harriers during migration 178. Circeo National Park, Italy. Marsh Harriers Circus aeruginosus migrate across a broad front during both spring and autumn migration, and regularly undertake long powered flights over water, sometimes using islands as stopover sites (Cramp & Simmons 1980; Agostini & Logozzo 1998; Agostini et al. 2001, 2003; Panuccio et al. 2002; Sammut 2005). Although they are capable of migrating across the sea at night, many migrating Marsh Harriers appear to suspend migration when faced with a water barrier in the afternoon, electing instead to hunt before roosting at dusk (Panuccio et al. 2002; Agostini & Panuccio 2003). Migrating raptors most commonly select trees in which to roost, and in areas where woodland is scarce are often attracted to small clumps of trees (Kerlinger 1989). Marsh Harriers usually roost among rank ground vegetation during the winter and breeding season (Cramp & Simmons 1980), but we have regularly observed migrant Marsh Harriers roosting in trees in the central Mediterranean region. Since many other migrant raptors roost in trees, it is perhaps not unexpected that Marsh Harriers should also do so. On Malta, up to 200 Marsh Harriers have roosted at Buskett (a small wooded area where hunting is banned) in recent years (Sammut 2005), while on Marettimo, Agostini & Logozzo (1998) reported a flock of 100 roosting in trees on 28th March On 1st April 2002, a flock of 50 landed in the only wood on the island of Ustica, while five were seen roosting on the rocks along the shore there in March During autumn migration, observations at Circeo Promontory, central Italy, revealed at least 150 Marsh Harriers roosting in trees on 13th September 2002, despite the close proximity of a large wetland area in a protected National Park with ample ground-roosting sites (plate 178). We have also observed tree-roosting Marsh Harriers at the Strait of Messina (max. nine in spring 2004); Aspromonte Mountain, southern continental Italy (max. 14 in autumn 2004); Pantelleria, western Sicily (max. 11 in autumn 2002); and Mount Capodarco, central Italy (max. three in spring 2003). Tree species does not appear British Birds 99 July

4 to influence the choice of roost site. We have observed Marsh Harriers roosting in Holm Oak Quercus ilex, Stone Pine Pinus pinea, Austrian Pine Pinus nigra, Common Beech Fagus sylvatica, Black Poplar Populus nigra and Common Ash Fraxinus excelsior. In contrast to Sammut (2005), who concluded that migrant Marsh Harriers roost in trees only as a last resort, when it is the only available safe roost site, we consider that some Marsh Harriers on migration actively select to roost in trees, regardless of whether suitable ground cover is available. Finally, it is interesting that observations during the winters from 1999/2000 to 2004/05 showed that small numbers of Marsh Harriers regularly roost in trees at the Circeo National Park, central Italy, where large flocks of waterfowl and many Marsh Harriers winter. Within this period, numbers of tree-roosting birds peaked at nine, along with three Hen Harriers Notes C. cyaneus, in December Agostini, N., & Logozzo, D Primi dati sulla migrazione primaverile dei rapaci Accipitriformi sull isola di Marettimo (Egadi). Riv. Ital. Orn. 68: & Coleiro, C How do Accipitriformes behave during autumn migration at the Circeo Promontory (Central Italy)? Riv. Ital. Orn. 73(2): , & Panuccio, M Autumn migration of Marsh Harriers (Circus aeruginosus) across the central Mediterranean in Ring 25: ,, Corbi, F., Di Lieto, G., Pinos, F., & Panuccio, M Comparative study of the autumn migration of Marsh Harriers (Circus aeruginosus) at three sites of the central Mediterranean. Vogelwarte 41: Cramp, S., & Simmons, K. E. L. (eds.) The Birds of the Western Palearctic.Vol. 2. OUP, Oxford. Kerlinger, P Flight Strategies of Migrating Hawks. Univ. Chicago Press, Chicago. Panuccio, M., Agostini, N., & Massa, B Crossing the Tyrrhenian Sea: spring migration of Marsh Harriers (Circus aeruginosus), sex classes and relation to wind conditions. Vogelwarte 41: Sammut, M Marsh Harriers roosting in trees. Brit. Birds 98: Michele Panuccio and Nicolantonio Agostini MEDRAPTORS (Mediterranean Raptor Migration Network), Via Mario Fioretti, Rome, Italy; medraptors@raptormigration.org Hunting technique used by Eurasian Sparrowhawk attempting to catch a Common Swift On 27th July 2005, I was operating a tractordriven mower at Holkham NNR, Norfolk, to top thistles (Cardueae) among grassland of the grazing marshes. The mower was often surrounded by about 40 low-flying Common Swifts Apus apus a regular occurrence as the birds eagerly snap up flies and other winged insects that are disturbed from the grass during the mowing operation. About 150 m away, I noticed a male Eurasian Sparrowhawk Accipiter nisus fly in from the south, low to the ground, before landing abruptly in a low spot within the marsh. I stopped the tractor to look at the hawk with binoculars and, as it remained in the same area, eventually nestling down into the vegetation with its head held down almost flat with its back, I continued slowly towards it. Coming to within 15 m of the hawk, with a congregation of swifts wheeling around me in all directions, the hawk suddenly shot up at the nearest bird, which had unknowingly passed directly above the hidden predator. In a twisting, turning chase over a distance of about 50 m, covered in a few Andrew Bloomfield 20 Lancaster Road, Blenheim Park, Sculthorpe, Fakenham, Norfolk NR21 7PX seconds, the Sparrowhawk matched the swift s every move, almost grabbing its faster victim. Ultimately, it was simply not agile enough and the swift banked up at a crucial moment and ascended high in the opposite direction to avoid capture. Newton (The Sparrowhawk, Poyser, 1986) noted that Sparrowhawks will hunt small birds by deploying such a technique, particularly in open ground (he terms it still-hunting ) but does not mention swifts as victims in his account. The same author did, however, record Common Swift as a rare prey item of the Sparrowhawk; for a bird renowned for its exceptional speed and agility, the Common Swift might initially seem an unlikely prey species. I wondered whether, in the case described above, the Sparrowhawk had foreseen the situation of the swifts hawking around the tractor and used the low-growing flora as a potential ambush location? Or was it just coincidence that the swifts drew close, and the Sparrowhawk exploited an opportunistic situation? 368 British Birds 99 July

5 Common Tern apparently feeding on oilseed rape At about hrs on 3rd July 2005, while birdwatching at Wilstone Reservoir, Hertfordshire, another birder (unfortunately I did not ask his name) and I witnessed the following unusual behaviour. In a field of oilseed rape Brassica napus oleifera adjacent to the reservoir, we saw a Common Tern Sterna hirundo repeatedly diving down to the top of the crop, in a manner similar to that which it would employ to feed over water. The behaviour continued for several minutes, and I can only assume that the bird (probably from the small colony which breeds at College Lake, Buckinghamshire, some 3 km away) may have been picking up insects at the top of the crop canopy, although the rape had finished flowering and was in seed. Peter Hearn Selwood, 160 High Street, Aylesbury, Buckinghamshire HP20 1RE Eurasian Nuthatches feeding on Hawthorn berries The diet of Eurasian Nuthatches Sitta europaea is best detailed in BWP (Vol. 7, p. 303), which lists about 20 plant species. However, the berries of our common and widespread Hawthorn Crataegus monogyna are not mentioned. On 4th September 2001, two Nuthatches flew along the tops of a line of Hawthorn trees at my home, within a mature wooded suburb in Sheffield, South Yorkshire. They landed in the upper outer area of one of the Hawthorns and perched on twigs estimated at 8 10 mm in diameter. They began reaching up and taking and eating berries, swallowing them whole. Each bird took seven or eight berries before flying off. Interestingly, BWP does mention Crataegus as a food plant for Western Rock Nuthatch Sitta neumayer, a less obviously arboreal species. Mike G. Archer 14 The Elms, Chesterwood Drive, Sheffield S10 5DU Magpie foot-paddling Alexandra Louise Pollard School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3TL On 18th March 2005, on a mown grass lawn by the Main Building, Cardiff University, I observed a Magpie Pica pica foot-paddling. This behaviour continued for about ten minutes, when I counted some 15 bouts of about five seconds duration, interspersed with several minutes of pecking and walking. Two Lesser Black-backed Gulls Larus fuscus were also footpaddling close by. Foot-paddling is often exhibited by gulls and waders in order to obtain food. The behaviour, stepping repeatedly in the same location, generates vibrations and encourages earthworms (Oligochaeta) to rise to the surface. Anecdotally, the vibrations are thought to imitate rain hitting the ground, causing the earthworms to burrow out of the ground. Foot-paddling has been recorded in Common Raven Corvus corax (Ewins 1989), but I can find no published reference to this behaviour in the Magpie. I suggest that the observed Magpie had been able to learn that the gulls foot-paddling led to the appearance of food. Foot-paddling in gulls is considered to be an innate behaviour, modified by experience, and is not learnt (Buckley 1966), and the Magpie s behaviour could have been an instinctive one. However, the presence of the two foot-paddling Lesser Black-backs and lack of previous reports of Magpies footpaddling would seem to suggest that interspecific social learning is possibly the more likely explanation. Buckley, P. A Foot-paddling in four American gulls, with comments on its possible function and stimulation. Zeitschrift für Tierpsychologie 23: Ewins, P. J Raven foot-paddling. Brit. Birds 82: 331. British Birds 99 July

6 The note by Tom Gladwin concerning Lesser Redpolls Carduelis cabaret at garden feeders (Brit. Birds 99: 159) prompted a number of responses. Bob Frost commented that: In 1996, I was a member of a Royal Air Force Ornithological Society expedition to the Varangerfjord, Norway. We arrived at Vestre Jakobselv, our base for the first part of the survey, on 28th April. The area was covered with deep snow, and I bought bird seed, and fat balls in string bags, to attract birds to the base camp. One of the first species to arrive at the fat balls was Common Redpoll C. flammea; so redpolls have been attracted to food put out by humans for some time. In the UK, several readers have reported Lesser Redpolls visiting garden feeders during the 2005/06 winter. Counties from which these sightings were reported (with the food item taken, where specified) include: Cambridgeshire Notes Redpolls at garden feeders Calls of Northern Bullfinches (niger seed)*; Ceredigion (niger seed and peanuts); Greater Manchester (mixed seed and niger seed); Northamptonshire (niger seed and sunflower hearts); and Worcestershire (niger seed and sunflower hearts). Records marked * include Common Redpolls also. While it seems that the use of garden feeders by redpolls is a relatively recent development, at least in most parts of the UK, it is apparently now fairly widespread and no longer particularly unusual (and niger seed appears to be the best bet to attract them into your garden). We shall not publish further individual items on this topic unless they are of particular interest. The following readers responded to Tom Gladwin s note: Jenny Briggs, John Davis, Bob Frost, John Headon, John Le Gassick, Gary Palmer, C. M. Richards and Judith Smith. Eds In their excellent review of the Northern Bullfinch Pyrrhula pyrrhula pyrrhula invasion of autumn 2004, Pennington & Meek (2006) documented that, as well as the many individuals giving the distinctive trumpet call, many Northern Bullfinches gave a call that was similar to that of the British race P. p. pileata, the latter call being the one familiar to observers who had experienced previous irruptions of P. p. pyrrhula. The authors were rightly careful to note that it was not possible to state definitively from field observations of unmarked individuals whether the same birds made both the unusual trumpet call and the normal peeu call, recognising the potential for a varied repertoire among individual birds. In this context, the following observations may be relevant. Between 14th October 2004 and 1st May 2006, I trapped 277 unringed Bullfinches in a rural garden near the village of Nimtofte (56 26 N E), in eastern Jutland, Denmark, mostly of the (small) races europoea/coccinea, but also 50 individuals of the large pyrrhula race (differentiated by consistent size differences; see Fox in press). Birds were caught at more or less weekly intervals using mist-nets, and marked with standard Copenhagen Zoological Museum rings and unique colour-ring combinations that permitted identification in the field. Most Bullfinches utter the alarm/contact call on release after ringing, enabling a comparison of call types, including those of subsequent retraps. In 2004/05, of 30 large birds trapped, 25 called on release from first capture, of which 22 gave trumpet calls. Last winter, up until 1st May 2006, of 20 large birds trapped, 19 called on release and 17 of these gave trumpet calls. In 2004/05, seven birds that originally gave the trumpet call were recaptured (one twice), and all gave the same call on release. Two large individuals which wintered at the site in 2004/05, identified in the field on the basis of the colour-ring combinations, and which gave the trumpet call on release, were observed giving the trumpet call in the field on 12 and 5 occasions respectively, and were never heard to make the normal call. Three of the large birds gave a normal call on release and one of these was subsequently recaptured, when it gave a normal call on release. In 2005/06, six large, trumpeting birds were recaptured, three twice and one thrice and all repeated the trumpet call on every occasion, while two large normal-calling birds were recaptured, one 370 British Birds 99 July

7 twice, and both gave the normal call when released. Of a total of 213 trapped small Bullfinches (of the local form P. p. coccinea) for which the call was recorded after release at first capture, in both years combined, 149 called, all with the normal call (14 others were not recorded). Of these, 61 were captured more than once and consistently gave the normal call (two individuals which were recaptured six times in the course of winter 2004/05 did so upon each release). Overall, including retrapped birds originally caught before 14th October 2004, the handling of 230 coccinea Bullfinches on 310 different occasions resulted only in normal calls, and 41 resightings of calling small birds in the field all involved normal calls, there being no record of a trumpet call from this subspecies. From observations of colour-ringed birds attending the garden feeder and in the immediate environs, it was evident that large birds (including individuals known to utter one or other of both calls) tended to occur together in a group at the study site, although they did also mix with coccinea. Under these circumstances, and in situations where there were no individually recognisable birds, it would be possible to conclude that large individuals could potentially give both calls. Clearly, these observations do not provide unequivocal evidence that individual birds only utter one of the two types of calls. Nevertheless, they provide circumstantial evidence that marked birds in this study were all consistent in their use of calls (at least under the circumstances reported here) and confirm that those colour-marked individuals making the distinctive trumpet call were never heard to make the normal peeu call, despite many potential opportunities to witness such an event. Fox, A. D. In press.the 2004 invasion of Bullfinches Pyrrhula pyrrhula in Western Europe: a mix of local, trumpeting birds and others of unknown origin. Bird Study. Pennington, M. G., & Meek, E. R The Northern Bullfinch invasion of autumn Brit. Birds 99: Dr Tony (A. D.) Fox Department of Wildlife Ecology and Biodiversity, National Environmental Research Institute, Kalø, Grenåvej 12, DK-8410 Rønde, Denmark; tfo@dmu.dk EDITORIAL COMMENT Mike Pennington and Eric Meek have commented as follows: We are very interested to read of Tony Fox s results, which provide some statistical support for our casual field observations. We would reiterate Tony s caveat that this does not prove that both calls cannot be made by one individual, but it does suggest that any claim that this is the case should be backed up by strong evidence. Further evidence from stable-isotope analysis has also confirmed our tentative suggestions that birds in the 2004 influx may have come from a wide geographic area (Newton et al. in press.), which may help to explain the two different call types. What is still a puzzle is why the trumpet call is new to so many observers, especially as Mark Constantine (pers. comm.) has informed us that Bullfinch calls collected by the Sound Approach team in Finland in the breeding season are all of the trumpet type. It is difficult to be certain about this, but it seems unlikely that our Finnish correspondents would be completely unaware of the trumpet call unless it was a new phenomenon. It may be that trumpet-callers have only recently started breeding in Finland, perhaps only temporarily following earlier invasion(s). Clearly, more information on the situation in Finland would be welcome. Finally, another interesting point to note from Tony Fox s contribution is the abundance of trumpeter Bullfinches at his site in both 2004/05 and 2005/06. Correspondents in The Netherlands, France, Switzerland and Italy, as well as Denmark, have all informed us that they have had as many trumpet Bullfinches in 2005/06 as they had following the 2004 invasion. The 2005 movement clearly followed a different route from that of 2004, however, as although a few birds were recorded in Sweden in late October, there were, as far as we are aware, relatively few in Scandinavia, while hardly any reached Britain; e.g. the Shetland Bird Club database has records of only 16 individuals in autumn 2005, excluding Fair Isle records, although three of these were definitely giving trumpet calls. Reference Newton, I., Hobson, K. A., Fox, A. D., & Marquiss, M. In press. An investigation into the provenance of Northern Bullfinches Pyrrhula p. pyrrhula found in winter in Scotland and Denmark. J. Avian Biol. British Birds 99 July