174 



BRITISH BIRDS. 



[vol. xiir. 



did not go to sea again until November 9th. Thus I missed 

 what appears from my notes for 1917 to be the busiest period 

 of the autumn migration. From November 9th we had 

 very rough weather for ten days and no birds were seen on 

 migration west of Malta. Then we returned to Malta and 

 went into dry dock until well after the cessation of the 

 autumn migration. 



The spring migration of 1917 began about the last week 

 of March and lasted till the first week of June. The autumn 



Fig /. 



FfG a. 



March 

 April 



May 



Fig 3 



spring migration i917. 



Fig. I. WESTERN AREA. Fig. 2. EASTERN AREA. 



April 



May 



June 



3 

 10 



17 

 24 



I 

 8 



15 



22 



29 

 5 



Fig. 3. COMBINED. 



migration of 1917 began about the end of September and 

 lasted till the end of November. For the purpose of charting 

 these seasons I have prepared figures consisting of a number 

 of squares (see Figs, i, 2, 3). Each horizontal line represents 

 a week, each small square a day. Those dates on which we 

 were not at sea I have left blank ; those dates on which we 

 were at sea I have shaded ; those dates on which migrating 

 birds were seen I have blacked in. I have further roughly 

 divided the Mediterranean into western and eastern areas 



