_Measurements._ +----+-----------+-----------+---------+---------+-----------+----------+ |Sex.| Wing. | Tail. | Culmen. | Tarsus. |Middle Toe.|Specimens.| +----+-----------+-----------+---------+---------+-----------+----------+ | ♂ |14.50–00.00| 9.00–00.00| .90–0.00|2.12–0.00| 1.90–0.00| 1 | +----+-----------+-----------+---------+---------+-----------+----------+ | ♀ |15.50–15.75| 9.50–10.00|1.00–1.05|2.00–2.35| 2.00–2.10| 2 | +----+-----------+-----------+---------+---------+-----------+----------+ HABITS. In treating of the general habits of the Gerfalcons of North America it will not be necessary, nor will it be possible, to give the distinctive peculiarities belonging to the several forms in which these Falcons occur. Whether, on account of their variations of plumage, we consider them as races or as specifically distinct, does not affect their history in this respect. There is no good reason for presuming that they have any very noticeable variations as to any of their habits, although certain writers claim for some of them certain well-marked peculiarities of character. In the matter of geographical distribution they are all, for the most part, rarely seen, even in midwinter, south of the 50th parallel of north latitude, and are found in the summer as far north as the Arctic Ocean. The Gerfalcon of the McKenzie River region, occurring from the Slave Lake to Anderson River and the Yukon, is the form elsewhere given as the _F. sacer_. Along our eastern coast region occurs another form, the _F. labradora_, which is the bird met with in Labrador, and described by Mr. Audubon. The _F. candicans_ or _grœnlandicus_ is a form peculiar to Greenland, visiting also, in the winter, the Hudson’s Bay region; while the _F. islandicus_, a well-known European form, occurs in Greenland also, and occasionally farther south. Holböll, in his account of the birds of Greenland (Isis, 1845), appears to recognize but one species of Gerfalcon as occurring there, to which he gives the name of _islandicus_. This is, he states, the most abundant Falcon in Greenland, and is equally common in the northern and in the southern parts. Their great variations in color he regarded as indicative of differences in ages to only a very limited extent, and as in no respect specific. These differences in color were found among both nestlings and breeding birds, white and dark birds being found together in both circumstances. The white birds were more numerous in Northern Greenland, and the dark ones oftener seen in the southern portion.