282 SPOLIA ZEYLANICA. 
point and from start to finish of their journey ? The great 
majority cannot possibly be guided by unaided sight or 
memory, as most of the migration takes place at night, and 
often over hundreds of miles of trackless ocean. Again, in 
many species, the young birds migrate apart from their 
parents, and so have no bird with actual experience of the 
route to guide them. The older Cuckoos leave England some 
weeks before the yearling birds, which have been brought up 
mainly in the nests of English residents and have never seen 
their parents. Yet the young Cuckoos hatched in England 
manage the long autumn trip over strange ground to their 
winter home which lies in Africa, south of the Sahara. There 
is no doubt that birds possess a special and mysterious sense of 
direction, known technically as “ orientation,’’ or, as Professor 
Newton phrases it, “inherited but unconscious experience.” 
Explorers in Antarctic seas have come across flocks of 
flightless Penguins trudging along over the open ocean to 
breeding grounds hundreds of miles away. Practical experi- 
ments with other birds have also proved their possession of 
this mysterious power of direction. The Florida Keys are the 
most northerly breeding grounds of the Noddy and Sooty Tern. 
Fifteen marked birds of these two migrant species were taken 
from their nesting haunts on one of these Keys and placed 
on board a steamer. They were then released at distances 
varying from 20 to 850 miles away. Some of them were set 
free off Cape Hatteras, many degrees northward of their usual 
range. Thirteen out of fifteen found their way home. 
It is also fairly obvious that in the course of long flights, 
which may extend to over a thousand miles, many birds must 
frequently be blown by contrary winds far out of their direct 
route, so that, if they had not this sense of direction, few would 
ever reach their destination. 
But this sense, as might be expected, is by no means 
infallible, and birds often stray. No doubt the majority of 
these strays come to a tragic end, but some find unaccustomed 
havens, and account for the irregular appearance of many 
species far away from their usual haunts. Some of these waifs 
may owe their salvation to falling in with a train of another 
species using a different route. This explanation has been 
