220 
BIRDS OF PENNSYLVANIA . 
New Castle, Delaware; correctly speaking, however, we cannot properly 
regard these birds as winter residents of the Keystone State. 
For a period of about one month following their vernal arrival they 
roam over the country, frequenting chiefly meadows, low lands and 
plowed fields. On the approach of night they collect in large numbers 
in some favorite roosting place, such as cedar or pine trees, thick woods, 
or dense thickets. 
Nest-building is usually begun about the middle of April, although 
on two or three occasions I have found nests, with full complements of 
eggs, as early as the first week in April. 
In colonies of from ten to twenty, seldom more, they locate them¬ 
selves for the purpose of nidification and reproduction. In this locality 
(Chester county) their favorite breeding resorts are apple orchards, the 
fruit and other trees commonly about the habitations of man. The nest 
is bulky and rudely constructed externally of rootlets, small twigs, dry 
plants, bits of corn-blades, etc., somewhat loosely but quite firmly 
bound together. Mud or mudded materials frequently enter into the 
construction of the nest, but this is not always the case; the interior is 
lined usually with fine grasses; occasionally I have seen leaves and feath¬ 
ers constituting the internal lamina. The construction of the nest 
occupies about one week; both sexes engage in its erection. It is 
built at the junction of two or more large-sized limbs or among the 
sprouts and matted twigs. The nests vary somewhat in size, but the 
one now before me—about the average—gives the following dimensions: 
Height, 6J inches; diameter, 7| inches; depth of cavity, 3 inches. 
Gentry observes that the female begins to deposit her eggs, one ovum 
per day, the day following the completion of the nest. Such may be 
the case, but my observation has been that oviposition does not often 
take place until three or even five days subsequent to the completion of 
the nest. The complement of eggs is commonly spoken of as six; gen¬ 
erally, however, I have found five, and regard this number as the full quota. 
The eggs are light greenish (sometimes pale rusty-brown), spotted, 
blotched and lined with black and dark-brown; they measure about 1J 
inches long and .90 of an inch wide. The period of incubation is from 
fourteen to fifteen days. The parent birds evince marked solicitude for 
their nest and its contents. 
It is evident from the writings of various authorities that the nesting 
sites of this species vary considerably. By Nuttall and others we are 
informed that they sometimes build in bushes. From the works of 
Audubon it is learned that in the south they build chiefly in hollow 
trees. I have found these birds building in common house ivy (Hedera 
helix) but never in bushes, and only on two occasions have I discovered 
their nests in hollow trees; both of these nests were built in apple trees. 
One was constructed in a limb about seven feet from the gxound, the 
