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«Pallid Swift: new to Britain and Ireland W. G. Harvey I n east Kent, 13th May 1978 began cold and damp with a light north- westerly wind and ...»

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Pallid Swift: new to Britain

and Ireland

W. G. Harvey

I n east Kent, 13th May 1978 began cold and damp with a light north-

westerly wind and intermittent rain. At dawn, D. Raine and I embarked

on a Kent Ornithological Society sponsored bird count through the Stour

Valley east of Canterbury. When we reached Stodmarsh at mid morning,

there was a perceptible rise in temperature and signs of a break in the clouds

which encouraged us to put aside earlier doubts and continue. As we

walked along the Lampen Wall across reed beds and lagoons of the National Nature Reserve, it was obvious that there was a substantial passage of Swifts Apus apus moving low WNW up the Stour Valley.

Shortly after passing three other birdwatchers (M. Marsh, M. Morley and P. Murphy) at about 10.30 GMT, we noticed a decidedly paler swift with a more deliberate flight. As we watched, it began feeding up and down the Wall, along a flight path of about 200 m, regularly passing us within 2 m.

We watched it for about 15 minutes, made field notes and then walked back to the others who had been joined by C. Clark. They had also been watching the bird and we all agreed that it was probably a Pallid Swift A.

pallidus. We watched it together for the next 40 minutes down to 2 m and from all angles, in dull light using a variety of binoculars. It was in company with up to 30 Swifts throughout.

The main features were the milky brown plumage, with dark brown primaries contrasting with paler secondaries and wing-coverts, the extensive pale face and throat, and the more deliberate flight, with shallower wing beats, more gliding and less agility than shown by its commoner companions. We were all conscious of the difficulties of field identification in view of the warnings given in current field guides and the fate of earlier, claimed British records. When we felt we had sufficient details to make identification certain, DR and I walked on to Grove Ferry to telephone the news as widely as possible. As the bird was easily watched from a footpath with no risk of disturbance, we were anxious that as many people as possible should see it. In the event, over the next nine days many hundreds saw it, and several photographs were taken (plates 99-104 and Brit. Birds 71: plate 135). It regularly appeared with Swifts at about 07.30 170 [ Bril. Birds 74: 170-178, April 198! J 171 Pallid Swift: new to Britain and Ireland hours and moved off, generally westwards, at about 16.30 hours, although on some days it was absent (or high out of sight) for long intervals. It was apparently never seen away from Stodmarsh. The last documented sight- ing was by Dr P. M. North on 21st May, although there were unsubstan- tiated reports up to 24th May.

Description Although this was known to be probably the first acceptable record in Britain and Ireland of a notoriously difficult species, only four descriptions were submitted to the Rarities Committee or the KOS apart from those of the original six observers. These came from R. E. E. Collins, Dr P. M.

North, D. W. Taylor and R. E. Youngman, and the following summary of the identification features draws on their notes as well as those of the original observers. My drawings are based on field sketches made on 13th May.

GENERAL APFEARANCE Appeared about size of Swift, though rather bulkier, with larger head, blunter wing-tips, broader wings and blunter tail fork. Generally paler, milkier 99-101. Pallid Swift Apuspallidm, Kent, May 1978 {DaridM. Cotlndge)

–  –  –

head particular!) noticeable in head-on views and probably contributed to impression of larger head than that of Swift.

t'N'DERPARTS Breast and belly appeared dark brown in most lights a n d contrasted with

undcrwing-covcrts. secondaries and throat:

seemed as d a r k as mantle, although more often in shadow (perhaps not real plumage characteristics, since H u d s o n did not notice it on skins). Showed scaling in close views, particularly on Hanks (I gained impression this created by d a r k borders to feathers, a l t h o u g h others noted pale borders similar to those on wing-coverts and mantle).

BARE PARTS Eyes and bill dark, probably black. M. M a r s h noted orange gape. Feet not seen.

GENERAL CHARACTERS Almost all observers Fig. 2. Pallid Swift Apus pallidus, Kent, Ma c o m m e n t e d on striking flight: steadier, more 1978 (from field sketch: IF. G. Harvey) deliberate, heavier and less manoeuvrable t h a n that of Swift. Wings a p p e a r e d broader, b l u n t e r and more blade-shaped, giving impression of shallower wing beats from the m a t i c t h a n that employed by the numerous shoulder (reminding me of the larger swifts, Swifts always present. After initial contact at Alpine A. metba and Mottled A. aequalonalis). close range, it could be picked up with naked M e t h o d of feeding while beating u p and eye at 100m, on flight style alone, even when d o w n dyke or e m b a n k m e n t was more syste- a m o n g m a n y Swifts. No call heard.

All observers with whom I discussed the bird were struck by its distinctive 'jizz' (indeed, it was a matter of concern that it was so distinctive!) and this was clearly a particularly striking individual in exceptional circumstances which allowed very close views in a variety of light conditions over quite a long period.





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Fig. 3.

Pallid Swift Apus pallidus from above (left) and below, Kent, May 1978 (from field sketches:

W. G. Harvey) occurred on 13th May, after winds had moved from light northerly on 9th and 10th to fresh E N E on 11th and light northwesterly on 13th. T h e passage of a cold front on the morning of 13th encouraged Swifts to move quickly through Kent. Over the following week, the winds were variable and light, moving to northeast on 20th and 21st, when the Pallid Swift was last reliably recorded. At Sandwich Bay Bird Observatory (15km ESE of Stodmarsh) Swift passage peaked on 13th-14th and 20th-23rd May, with only small numbers on 24th-26th (Martin Sutherland in litt.). Thus, the Pallid Swift arrived with the first peak and left with the second. If it was of the west Mediterranean race hrehmorum, it seems likely that it joined a build-up of northward-bound Swifts in the Mediterranean. Its striking paleness, however, at least admits the possibility that it was from farther south, and of the Saharan/Middle-Eastern race pallidus. With supremely aerial birds such as swifts, the possibility of distant origins for vagrants is greater than for most species, and the full range of subspecific characters must be borne in mind when attempting to identify a vagrant.

Distribution Vaurie (1965) gave the range as 'Madeira, Canaries, north western Africa, coastal regions of the Mediterranean and some of its islands and the Sahara westwards (sic: presumably eastwards is meant) through Egypt and the Near East to Iraq, southern Iran and southern Baluchistan'. He described three Palearctic races: brehmorum in the western Mediterranean, the darker illyricus in the eastern Mediterranean, and the paler pallidus in the Sahara and the Middle East. He considered that two further races, niansae of East Africa a n d somalicus of Somalia, may be conspecific, but White (1970) and Brooke (1978) considered these to be races of the Nyanza Swift A. niansae, forming a superspecies with A. pallidus.

T h e Pallid Swift is both migratory and resident, and there are single records from Uganda, Zambia and Cape Province. Unfortunately, the high flying of migrant and wintering swifts and the difficulties of field identiPallid Swift: new to Britain and Ireland

109. Swifts Apm apus, Lanarkshire (Strathdydc), June 1949 (C. Em Falmtf)

fixation, particularly in the range ol'niansae, mean that the migratory habits are not fully known, and these three Afrotropical records may not be typical.

In Europe, the northern limit of breeding is Piedmont, Italy (Boano 1979), while in France Pallid Swifts were first found in Corsica in 1932 and breeding proved there in 1936. Breeding was first confirmed on the mainland in 1950, and all breeding records are from the Mediterranean littoral except for a population in the Toulouse area discovered in 1966 (Ycatman 1976). This French evidence suggests a slow extension of range northwards, although R. Cruon (in lilt.) knows of no more northerly French records. Further, P. Goriup (in litt.) and Robert Hudson (in litt.) have been unable to trace any published records from elsewhere north of the breeding area, presumably because the difficulty of field identification precludes most claimed sightings from acceptance. A Pallid Swift at Bath, Zeeland, Netherlands, on 8th August 1979 was the first Dutch record (G.J. Oreel in litt. to Dr J. T. R. Sharrock). Interestingly, Bath is on almost exactly the same latitude as Stodmarsh (about 51° 20' north).

Throughout most of its range, the Pallid Swift is no more than locally common. Its habitat corresponds to that of Swifts, similarly nesting in cliffs and buildings. It usually favours more open locations in buildings and never utilises holes in trees as the Swift does in eastern Europe and Siberia.

Many, but not all, breeding colonies are in coastal towns and cliffs. The western Mediterranean subspecies hrehmorum returns to its breeding area in March and leaves in November. Its season is thus at least two months longer than that of the Swifts in the same area, which suggests a much shorter migration for most individuals.

–  –  –

sighting should not obscure the difficulty of separating Pallid Swifts from Swifts in the field. Light conditions have a variable effect on the apparent coloration, since the differences are largely matters of degrees of shade.

Wind conditions affect the mode of flight. Young Swifts are often paler than adults, show a more extensive pale throat patch and some mottling or scaling. There is also the possibility of unusual plumage variants and leucistic Swifts may be particularly misleading (e.g. Vinicombe 1978).

The Central Asian race of the Swift A. a. pekinensis is intermediate in coloration between the nominate race and the darker races of the Pallid Swift. It has a larger throat patch than the nominate race and may show pale tips to the breast and belly feathers. Its primaries are darker than its secondaries. I n an examination of skins at Tring, Robert Hudson could find no single plumage character which consistently separated all pekinensis from all Pallid Swifts. Since this subspecies ranges west to Turkey and the Levant, its occurrence in western Europe is possible, and it is necessary to exclude it in the field identification of suspected vagrant Pallid Swifts. This may not always be possible, particularly with distant views of single birds.

Lack (1956) discussed the differences between Swifts and Pallid Swifts, and also noted that most features are a matter of degree, with some overlap between the two species in most characters. He found that on most Pallid Swifts the first and second primaries were equal or almost so, while on Swifts the second was usually longer. P. R. Colston (in lilt.), however, in a more recent examination, found that the overlap is considerable, although there is a tendency for Apus apus to have longer second primaries (table 1). Lack (1956) confirmed Hartert's findings that the tails of Pallid Swifts are generally less forked than those of Swifts, and this was further confirmed by Colston (table 2).

On the basis of the comments of Lack (1956) and Robert Hudson (in litt.), and the available descriptions of the Stodmarsh individual, I suggest

–  –  –

that the following are the main identification features of Pallid Swifts when

compared with Swifts in the field:

/. Paler, milkier brown plumage

2. Dark brown outer primaries contrasting with paler secondaries and wing-coverts (compare with the contrary effect on Swifts)

3. Breast, belly and especially mantle appear darker than wing-coverts, head and rump.

The darker mantle can create a saddle effect and seems to be a consistent feature independent of light conditions, whereas the dark underparts may only be a factor of shadow

4. Pale, whitish throat extendingfarther down breast, to sides of neck and ontoforehead

5. Distinct mottling or scahness on contour feathers, most noticeable on wing-coverts andflanks

6. Dark eye shadow mark often showing clearly on pale head. Although afactor of light conditions, this can be a strikingfield mark

7. More blade-shaped wings, broader based and, usually, with blunter wingtips. Less obviously, the tail points look blunter and thefork shallower

8. Less agile, more deliberate flight, with more gliding It is likely that most, if not all, of these characters need to be clearly seen in good light conditions and at close range, preferably in direct comparison with Swifts, if certain identification of vagrants is to be established.

Acknowledgments I a m grateful to those who submitted descriptions of the Stodmarsh Pallid Swift, but, although I have m a d e use of their notes, the responsibility lor what goes before is entirely mine. I am also very grateful for the considerable help and constructive criticism of P. Britton, D r N. Collar, P. R. Colston, R. C r u o n, P. Goriup, R. Hudson, M. J. Rogers, D r J. '['. R. Sharrock, M.

S u t h e r l a n d a n d D. VV. Taylor. I also thank Jeff Pick and David M. Gottridge, who took the p h o t o g r a p h s, and M r s Sylvia Bastian, for typing the drafts.

Summary T h e first accepted Pallid Swift Apus patlidus in Britain and Ireland was seen at Stodmarsh, K e n t, d u r i n g 13th to 21st M a y 1978. Details of the species' world range are given and the identification problems are discussed.

References BOANO, G. 1979. II Rondonepallido/l/)«j/)affirf«jin Piemonte. Riv. Hal. Orn. 49 ( I I ) : 1-23.

BROOKE, R. K. 1978. In Snow, D. \V. (ed.) Alias of Speciation of African Non Passerine Birds.

London.

BUNDY, G. 1976. Checklist of the Birds of Libya. London.

C A R E Y, R. 1973. A Guide to the Birds of Southern Portugal. Lisbon.

E T C H E C O P A R, R. D., and H U E, F. 1978. Les Oiseaux de Chine Nonpassereux. Tahiti.

LACK, D. 1956. T h e species of Apus. Ibis 98: 34-62.

M O R E A U, R. E. 1971. The Palearctic-African Bird Migration Systems. London.



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