XIV MIGRATION 365 
affects only one migration, either that of spring or 
autumn, since the large quills are shed only once in 
the year, The Swallow having his one moult in early 
spring is detained in England by family cares only. 
The Swift leaves us much earlier, and as he rears only 
one brood, and as his main moult takes place in spring 
he is free to go. The old Cuckoos go, asa rule, before 
August ; like the Swift they moult chiefly in spring, 
and their young are in the charge of others. The 
majority of our migrants shed their wing feathers in 
autumn, and, if it were not for that, would, probably, 
start southwards earlier. 
In spring the order of departure is reversed. First 
come the old cock birds, the finest of all it is said 
leading the van ; then old hen birds ; then old hen birds 
and young birds mixed; then young birds alone ; 
and, lastly, cripples in every stage of dilapidation. 
In some cases it may be that two sets start together, 
but that the stronger birds outstrip the weaker and 
hence the different dates of arrival for the different 
sexes and ages. But Mr. Seebohm speaks of the 
young Swallows at Natal being later with their mault- 
ing than the old birds, and this necessitates a later 
start. Besides, if it were a race for which all 
started level, probably some of the hen birds would 
arrive with the first detachment, and this does not 
seem to happen. 
‘Partial Migrants. 
This name has been given to species some indi- 
viduals of which migrate, while others remain resident’ 
throughout the year. In England the old Robins 
