398 USEFUL BIRDS. 
All the rooms will be backed by this, and the pole will go 
into it. The pole may be made to go into a socket in the 
ground, and then both pole and house may be taken down 
in the fall and kept under shelter until the Martins return in 
the spring; or, if the pole is hinged near the bottom, the 
‘box may be still more readily taken indoors. This will 
prevent the Sparrows from intrenching themselves within. 
If a cedar pole is used, the bottom should be well tarred 
wherever it comes in contact with the ground. It should 
be set deep in the ground to give it the requisite firmness. 
If the nests of Martins are dusted occasionally with fresh 
insect powder, it will relieve them of the vermin which 
always congregate in large, occupied bird houses. 
Furnishing Nesting Material. 
An abundance of suitable and easily accessible nesting 
material may chiefly influence some birds in choosing a site 
for a home. 
It is now believed that the Parula Warbler breeds only 
where the usnea moss grows luxuriantly, for in this moss she 
usually secretes her nest, constructing it largely of the same 
material. Robins, Swallows, and Phcebes must have mud for 
nest building. The Chipping Sparrow lines her nest with 
hair, usually that of the horse, cow, or deer. Vireos and 
Orioles must have hair or strands of some kind to construct 
the pendent fabrics which they skillfully weave. If we hang 
nesting materials gn bushes, trees, or fences, or place them 
on the ground in the open, where birds will be in no danger 
from cats while securing them, this may prove to be the final 
“straw ” which will decide several pairs of birds to nest on 
our premises. Such supplies, when watched, furnish ready 
means of tracing the nest builders to their nests. We can 
then take means to protect the nests from marauders. Root- 
lets, fibers of birch, cedar or grape vine bark, straw, fine 
hay, hair, feathers, thread, twine, rope yarn, jute, sphag- 
num moss, —all will serve a purpose. It is important to 
furnish twine, hemp, yarn, or some similar material for the 
Orioles ; otherwise they may get it by tearing to pieces the 
nests of other birds which have used such materials. In 
