THE MISSION OF THE BIRDS 
l 9 
And in the branches and among the leaves sparrows and warblers 
are abundant, ever searching for the tiny foes to plant-life. 
The transition from the shrubby border of the forest to the forest 
proper is generally gradual, and there is more or less connection 
between the insect life as well as the bird life in the two areas. On 
the whole insects exist in the forest in less variety than in the 
shrubby growth or the open fields. As a rule there is little food for 
them on the ground beneath dense woods, so that their food supply 
is limited to the trees themselves. Upon these, however, they are 
very often destructively abundant 
of various beetles, some species 
of which go deep into the trunk 
branches, while the 
and leaves are infested 
many sorts of bark-lice, 
The bark is full of the burrows 
or largei 
twigs 
by 
plant-lice and caterpillars. Of 
the leaf-feeding caterpillars, 
some go to the ground to pu- 
pate, and there they form an 
important part of the food of 
the ruffed grouse, which is one 
of the few birds that searches 
the soil surface in dense woods. 
The woodpeckers look after 
the bark and trunk borers, as- 
sisted more or less by the nut- 
hatches and creepers; while 
the plant-lice and the leaf cat- 
erpillars are always in danger 
from the hungry beaks of the 
chickadees, kinglets, warblers, 
Even the comparatively few insects found in marshes, along the 
shores of ponds, and living in the water itself are not free from bird 
attack. The blackbirds of various kinds, the numerous sparrows 
that live in lowlands, the snipe, woodcock, sandpipers, plovers, and 
rails, the herons and bitterns, the ducks, coots and grebes, all find 
in these insects part of their diet. The catbird makes a specialty 
of catching dragon flies just after they have emerged from their 
nymph stage, when they are waiting for the wings to harden before 
The Yellow Warbler 
vireos, ovenbirds and thrushes. 
