210 USEFUL BIRDS. 
tracted by the berries of the mountain ash. The northward 
migration is usually under way in March, but comparatively 
few birds are ordinarily seen in central Massachusetts until 
late in May. In spring and early summer they seem to feed 
almost entirely on insects. They are always plentiful at this 
season in a cankerworm year, and they deserve at such 
times the local name of “cankerworm birds,” for they fre- 
quent infested orchards in large flocks, and fill themselves 
with the worms until they can eat no more. There is no 
doubt that the countless thousands of caterpillars that they 
destroy more than compensate for the cherries they eat, 
although in some seasons they are very destructive to cherries. 
Such little gluttons rarely can be found among birds. The 
Cedar Bird seems to have the most rapid digestion of any 
bird with which experiments have been made. Audubon 
said that Cedar Birds would gorge themselves with fruit 
until they could be taken by hand; and that he had seen 
wounded birds, confined in a cage, eat of apples until suffo- 
cated. They will stuff themselves to the very throat. So, 
wherever they feed, their appetites produce a visible effect. 
Professor Forbes estimates’ that thirty Cedar Birds will 
destroy ninety thousand cankerworms in a month. This 
calculation seems to be far within bounds. 
Cedar Birds are devoted to each other and to their young. 
Sometimes a row of six or eight may be seen, sitting close 
together on a limb, passing 
and repassing from beak to 
beak a fat caterpillar or juicy 
cherry. I have seen this 
touching courtesy but once, 
and believe it was done not 
so much from politeness as 
from the fact that most of 
the birds were so full that they had no room for more, —a 
condition in which they can afford to be generous. Never- 
theless, the manner in which it is done, and the simulation 
of tender regard and consideration for each other exhibited, 
render it a sight well worth seeing. They also have a habit 
of “ billing,” or saluting one another with the bill. 
Fig. '75.— Passing the cherry. 
