VI FORM AND FUNCTION 157 
of Bean Geese that he saw in the north of Russia, 
making for the water when their moult was imminent. 
By the time the young can fly, the old birds have 
renewed their quills, and they start for the south 
together. Any land bird with such a system of 
moulting would be reduced to asad plight. He would 
be worse off than the Crayfish, who has cast his shell 
and, cowering in a hole, waits for the new one to form 
and harden. As far as is known, all birds who are 
not at home upon the water, shed their large feathers 
at intervals, a pair at a time, one feather from each 
side. In Hawks and other birds of prey, the intervals 
are very long, and the process continues nearly the 
whole year. In Homing Pigeons—the breed now in 
use for “carrying ”—and, I believe, in other pigeons 
also, the moult lasts nearly half the year. About 
May the tenth of the eleven primaries counting from 
the outermost is lost. A month later the ninth goes. 
By that time the tenth has grown nearly to its full size ; 
when the ninth is about half its proper length, the 
eighth falls; the others follow at intervals of from 
eight to fifteen days. In the tail, which has twelve 
feathers, the two which are fifth from the sides fall 
first. When the new ones are grown to three quarters 
of their full length, the two central ones are shed ; the 
remainder fall in this order: the fourth, the third, the 
outermost, the second. The Pigeon suffers much as 
the moult approaches its conclusion. He flies with 
difficulty, and is liable to arthritis, commonly known 
among Belgian fanciers as La Maladie des ailes. 
Badly fed birds have a defective moult. If Pigeons 
1 See his Siberia in Europe, p. 287. 
