BIRDS AND LIGHTHOUSES 267 



separately, and apart. Each goes its own pace, 

 and the flocks then keep well together on their 

 route. 



Another fact which has been ascertained and 

 placed beyond doubt by experiments made at 

 various times and places, is that the same in- 

 dividual birds return year by year to particular 

 spots where they have successfully reared their 

 young. This has been proved by the experiment 

 of catching birds on the nest without injuring them, 

 marking them by tying silver wire or coloured 

 twine round the legs, and restoring them to 

 liberty. The following year the marked birds have 

 been caught in their old haunts ! Nowadays, 

 therefore, no one doubts the fact of migration. 

 What we want to know, however, is the cause or 

 causes, the manner in which, and the faculty whereby 

 it is performed. 



It is remarkable that until quite recently no 

 English ornithologist had set himself earnestly to 

 work to try and solve these problems. It is true 

 that for the last century, ever since the days of 

 Gilbert White and Markwick (whose " Calendars of 

 Nature " are so familiar to us), hundreds of persons 

 have amused themselves with noting the earliest 

 and latest dates of arrival and departure of 

 migratory birds, and some of them have carried out 

 the practice for many years. But they have done 

 nothing more. Their observations have brought 

 us no nearer to a solution of the questions at 

 issue. Indeed the great mass of such reports 

 of the arrivals of migratory birds as are annually 



