424 K. C. PARKES 



(Erolia ferruginea) and the Ruff {Philomachiis pugnax) ; and two 

 are gulls, the Black-headed Gull {Lams ridibundus) and the Little 

 Gull (L. minutus)} 



What particular attribute, if any, do these six species share to 

 give them the propensity for such frequent Transatlantic crossings 

 against the prevailing winds? Three of the species, the two ducks 

 and the Black-headed Gull, are known to nest as far west as Iceland. 

 But why, then, do not other, related, Iceland nesters make the 

 same trip? Among the gulls, for instance, the Lesser Black-backed 

 Gull (Larus fuscus) breeds in Iceland, but the two specimens of 

 this species that have been collected in North America were both 

 of the British rather than the Icelandic breeding race. Of the three 

 remaining species, the Little Gull nests as far west as Denmark and 

 the coast of the North Sea, the Ruff to western France, and the 

 Curlew Sanrlpiper only in eastern arctic Siberia. The breeding ranges 

 of all these species are more or less duplicated by those of related 

 species or other birds of similar migration patterns. Why, then, do 

 we see these six so much more often along our East Coast? Several 

 possibilities suggest themselves. One is that other vagrant species 

 are being overlooked. Readers familiar with the zeal of the bird- 

 watching groups on Cape Cod or Long Island will discount that 

 one immediately. It has been said that the publication of Peterson's 

 Field Guide to European birds in 1954 was a real boon to many 

 Massachusetts bird-watchers, who had by then worn out their 

 Field Guides to the birds of western North America! 



Another possibility is some sort of innate tendency in these few 

 species to go astray, so to speak; perhaps a high incidence of error 

 in their "direction-finding apparatus," that mysterious organ for 

 which ornithologists still search in vain. This would be exceedingly 

 difficult to demonstrate, and seems rather unlikely from an evolu- 

 tionary point of view, since getting lost would not appear to be a 

 selectively advantageous trait. A third possibility and perhaps the 

 most reasonable, at least for some of the species, is the existence of 

 undiscovered breeding areas of these species much closer than any 

 we know of now, perhaps even in North America itself. Certainly 



1 The list of eight European birds most regularly observed on the Atlantic Coast of 

 North America presented by Lindroth (1957, p. 251), which overlaps the above list by 

 four species, was based on an obsolete and incomplete reference, the 1931 edition of the 

 A.O.U. Check-list. Even the 1957 edition is misleading in this respect; see Eisenmann, 

 1958, for remarks on the status of certain European birds in the New York City region. 



