106 CORRESPONDENCE IBIS 110

CORRESPONDENCE LARUS RIDIBUNDUS IN SPITSBERGEN

SIR,-Having read the paper by Messrs. M. A.,Ogilvie & R. J. F. Taylor entitled ' Summer records from West-Spitsbergen, 1964' (1967, ' Ibis 109 : 299-309), I feel that I am compelled to draw your attention to the fact that their record of Lurus ridibundus is not the first one from Svalbard. As early as 1961 Dr. Erik Halkier discovered one specimen on 27 June near Longyear City. This was published in the magazine of the Danish Ornithological Society (1961, Uszedvanlige observationer af m&ger pA Vest-Spitsbergen (with a summary in English: Some unusual observations of gulls in West-Spitsbergen), ' Dansk. orn. Foren. Tidsskr. ' 55 : 193-196).

Sorrentovej 12, ERIC KRAMSHoJ. 2300 Copenhagen S.,

Denmark. 24 September 1967.

PNEUMATIZATION OF THE CRANIUM AS A CRITERION OF AGE SIR,-Serventy, Nicholls .& Farner (1967, ' Ibis ' 109 : 570) stated that " It is not clear when it

(i.e., the pneumatization of the cranium) was first used as a criterion of age in passerine birds. . . , it was certainly in use by the turn of the century."

As far as I know, it was C. L. Brehm who first discovered that the pneumatization or ossification of the skull can be used as a criterion for estimating the age of birds. After having examined some hundred bird-skulls he reported on this new method in ' Beitrage zur Vogelkunde ' 11, p. 700 (1822). In order to make use of this in the study of bird skins he prepared some specimens of his famous collection in a manner that allowed examination of the ossification of the skull by lifting the skin of the nape (see fig. in ' Der Falke ' 1964, p. 151).

G. NIETHAMMER. Museum A. Koenig,

18 October 1967. Bonn.

WHITE-RUMPED SWIFTS IN SPAIN SIR,-Accompanying " short communications " from Messrs. F. G. H. Allen & P. G. C.

Brudenell-Bruce (1967, ' Ibis ' 109 : 113-115) is a photograph of a swift leaving its nest in a cavern in southern Spain. The same photograph, considerably enlarged and giving a clearer picture, is also used to illustrate a paper by Mr. I. J. Ferguson-Lees in ' British Birds ' (60 : 286-290). It is accepted in both publications that the swift in question if Apus .finis (Gray). Examination of the photograph, however, particularly that in ' British Birds , does not seem to support this identifica- tion. Not only does the tail appear to be well forked, but the three outer rectrices, particularly the two outermost, are markedly pointed, due to the emargination of the inner webs. The white of the rump is restricted to the back, and does not wrap around the flanks. These are all characters by which A. cuff0 (Lichtenstein) may be distinguished from A. ufinis. Furthermore, the white band on the rump in the photograph appears to be narrow, whereas A. ufinis koenigi (Reichenow), which breeds in Morocco, has the broadest white rump of any race of A. ufinis.

We feel, therefore, that despite the geographical improbability of A. cuffer occurring in Spain, A. ufinis should not be admitted to the European list of breeding species until a specimen has been obtained at the nest.

Since several of the observers who have seen swifts in southern Spain have had previous experience of A. ufinis, it may well be that two species are involved, ufinis and perhaps cuffe7, which was the one photographed at the nest. The breeding habits do not provide any precise clue to the identity of the species involved, since the northern populations of A. ufi;is, and all populations of A. cufer, use swallows' nests, though Ferguson-Lees (' British Birds 60 : 289) specifically mentions that these Spanish nests were more scattered than is usual for A. ufinis. We urge the collection of specimens in order to determine what species of white-rumped swifts really do breed in Spain.

Department of Zoology,

P.O. Box 8081, Causeway,

National Museum of Rhodesia,

C. W. BENSON. Downing Street,

Cambridge. R. K. BROOKE.

Salisbury, Rhodesia.

P.O. Box 240, Bulawayo,

Rhodesia.

M. P. STUART IRWIN.

Falcon College, P. STEYN. Essexville,

Rhodesia. 10 November 1967.