This occurred at the coldest period of the season, when the ground was covered with snow to an unusual depth, and when the thermometer indicated a temperature at that time frequently as low as 15° below zero.
The nest is usually of great size, composed of sticks from three to five feet in length, pieces of turf, weeds, and moss. Its diameter is about five feet, and its depth is not unfrequently as great. In the warmer localities, where it breeds, the pair usually frequent the same nest throughout the year, and make it their permanent place of resort. This is also true, probably, wherever this Eagle remains throughout the year. Mr. T. H. Jackson, of West Chester, Pa., informs me that he met with three fresh eggs of this species in Maryland, on the 11th of February, 1871.
The eggs are usually two, sometimes three or four, in number; they are nearly spherical, equally rounded at either end, and more or less granulated on their surface. Their color is a dull white, unspotted, but often stained by incubation to a dirty white or a light soiled drab. Two eggs in my collection present the following measurements: Length 3 inches, breadth 2.75; length 2.88 inches, breadth 2.80. The first was obtained in New Jersey by Alexander Wilson, the ornithologist; the latter by Dr. Trudeau, in Louisiana.
Another, taken from a nest in Texas by Dr. Heermann, measured 2.80 by 2.20 inches. A fourth, from Sitka, measures 2.75 by 2.25 inches. These measurements, so far as they may be taken as typical, exhibit but little variation in size between the most northern and the most southern specimens.
Several nests were met with and the eggs taken by Mr. MacFarlane near Anderson River. They were generally built in high trees not far from river-banks. In a few instances the parents made hostile demonstrations when their nests were robbed, but generally kept at a safe distance, uttering loud and discordant sounds. The nests were built of dry sticks and decayed branches, and lined with deer’s hair, mosses, hay, and other similar soft materials.
Mr. Dall was informed by the Indians that this species breeds among the Alaskan mountains on inaccessible cliffs. This statement, however, may have had reference to the Golden Eagle.
Falco communis (Europe), p. 138.