140 BRITISH BIRDS. 



evidence from all over the world, and the Mediterranean 

 is no exception, although I hardly think, from my 

 own observations in the latter district, that mere wind 

 in fine weather is to be looked on as the predominant 

 cause of derangement of migration routine for the 

 following reasons : — 



A. — The principal migration routes of the Mediterranean 

 are to a great extent dotted with land, and the chances 

 of effecting a pied-a-terre should an adverse wind spring 

 up are fairly good. Sea-distances are nowhere great. 

 To be blown out into the Atlantic or other great ocean 

 would be very different. 



B. — Birds will undoubtedly not start on their flight 

 across the sea if the wind is unfavourable, and although 

 weather in the Mediterranean may be very local, there 

 is generally a fair period of warning before strong winds, 

 so that the chances are greater that birds will have a 

 favourable passage, especially if the journey is not a very 

 long one. 



The effect of a strong head-wind upon migrating birds 

 was very noticeable on May 2nd, 1907, in Palmas Bay, 

 at the south end of Sardinia. 



Here, day after day, during the months of April and 

 May, in fine bright weather, very strong winds drive 

 down from the mountains seawards during the day time, 

 and subside again in the evening ; but they are quite 

 local winds, and do not extend many miles to seaward. 

 On this particular day the ship was manoeuvring about 

 Palmas Bay, and one of these very strong local winds 

 sprang up from due north early in the afternoon. No 

 migrants had been seen in the forenoon, but no sooner 

 had the wind freshened than migrating birds started to 

 appear — Redstarts, Wheatears and a Woodchat-Shrike 

 beating up to windward, hugging the surface of the water 

 to obtain the retarded velocity of air due to the water's 

 friction. Quite a few of these birds settled on board, in 

 spite of tlie fact that we were carrying out aiming rifle 

 practice, and what struck me as more remarkable still, 



