BREEDING. 
329 
to do so themselves. Thus the chicks are seen assembled 
round the mother, though they do not do so until she, 
after scraping, calls them, and begins to peck about 
herself. Young Water-birds are taught by their parents 
in a similar manner; Grebes, and others of the better 
Divers, require somewhat longer instruction. 
Those birds which are, so to speak, reared almost to 
maturity in the nest, naturally require much more 
parental care than the former. The parents are not 
only occupied with catering for their brood until these 
are ready to fly, and often for some time after, but have 
also other duties to perform. The generality of the 
Raptores, Crows, and a few others, alone avoid soiling 
their nests ; all other nestlings require the tender offices 
of the old birds to preserve them in a state of cleanliness. 
These carry away the excreta of the young from the nest 
in their beaks, and, to avoid discovery of the latter, often 
transport it some considerable distance. Pigeons and 
Hoopoes omit this act of cleanliness ; and every Pigeon- 
fancier is well aware how terribly the young of the former 
are infested with vermin. The actual business of feeding 
is alone no small matter. The everlasting little screamers 
require four times the nourishment the old birds do, 
which demand occupies their unremitting care and 
attention. Birds which feed their young from the crop 
have somewhat the advantage over others, inasmuch 
as they bring home more food at a time, and thus 
require to feed their young less frequently. All Warblers, 
as well as many other birds, are obliged to bring only 
a single insect, or at the most a few, in their beak 
at one time; and this occasions countless journeys to 
and from the nest: a pair of Goldcrests make a trip 
every three minutes. During breeding time noxious birds 
