NOTES. 255 



lemming have become practically parasitical on these animals, 

 and so far as I am able to judge are generally to be found in 

 greater numbers wherever these rodents are concentrated, 

 the result being that many more nests are built in the area 

 covered than would be the case under normal conditions. 

 Consequently many more nests are found by collectors in that 

 area, with both large and small clutches ; incubated clutches 

 of tooand three Rough-legged Buzzard have been found on 

 several occasions in a lemming year, and I do not consider 

 clutches of four and five are unusual, for it can be proved 

 that they are found every year ; clutches of six must be 

 considered exceptionally rare, and are probably produced by 

 old birds in their prime. 



The strongest evidence against food increasing the powers 

 of production is to be found in the fact that it does not 

 affect birds which normally lay a completed clutch of one, 

 two, or four eggs, though it is well known on rare occasions 

 that even those birds depart from the rule. 



It may be of interest to note that though Buffon's Skua 

 (S. parasiticus), which normally lays two eggs, also feeds 

 largely on the lemming,* no mention has been made of any 

 increase in the normal clutch of the species. 



Mr. Gilroy is somewhat emphatic in his remarks (antea, 

 pp. 222 and 223), but his " proofs " are not very convincing. 

 In regard to the Sparrow-Hawk, surely if these birds were 

 allowed to have their own way they would naturally largely 

 increase, and consequently there would be a considerable 

 diminution in the food-supply if Mr. Gilroy's theory is 

 correct, this would result in smaller clutches. I know the 

 sandy district in Norfolk to which he refers quite well, and 

 out of twenty clutches of Wood- Lark inspected, sixteen were 

 of four, three of five, and only one of six. In Devon and 

 Wales clutches of five and six occur in about the same 

 proportion. Mr. Gilroy does not say what favourite food 

 of this species is found in Norfolk that is not so plentiful 

 in Wales, nor what is the food found by the Raven on the 

 coast that is not found inland. 



Percy F. Bunyard. 



MIGRATION ACROSS THE MEDITERRANEAN. 

 With regard to migration routes across the Mediterranean I 

 obtained some evidence on the 4th and 5th April, 1909. We 

 were steaming for Port Said and were at the time south of 

 the Adriatic, in a region, therefore, which Commander Lynes 



* Robert Collett, " Birdlife in Arctic Norway," p. 38. 



