A Synopsis of the Birds of North America

by John James Audubon

Swallow-tailed Hawk, Falco furcatus, Wils. Amer. Orn. v. vi. p. 70.

Falco furcatus, Bonap. Syn. p. 31.

Swallow-tailed Hawk, Falco furcatus, Aud. Orn. Biog. v. i. p. 368. v. v. p. 371.

GENUS IX. FALCO, Linn. FALCON.

Bill short, robust; its upper outline decurved from the base; cere short, bare; edge of upper mandible with a festoon and a prominent angular process. Nostrils round, with an internal ridge, ending in a central tubercle. Feet strong; tarsi moderate, reticulate; toes long, broadly scutellate, the anterior webbed at the base; claws long, well curved, very acute. Wings long, pointed; second quill longest, first and third nearly equal; outer toe abruptly cut out on the inner web. Tail rather long, nearly even.

19. 1. Falco Islandicus, Lath. Iceland or Jer Falcon—Gyr Falcon. Labrador Falcon.

Plate CCCLXVI. Adult Female. Plate CXCVI. Young Male and Female.

Tooth-like process of the bill generally obsolete in old, festoon slight in young birds; tail from three to four inches longer than the wings. Adult white, with slate-grey sagittate spots above, the bill pale blue, the cere and feet yellow. Younger birds light grey, the feathers white on the edges; the bill and cere light blue, the feet greyish-blue. Young brownish-grey above, the feathers margined and spotted with reddish-white, the lower parts yellowish-white, longitudinally streaked with dusky.

Male, 22¹/₂, 49. Female, 23¹/₂, 51¹/₄.

Breeds in the extreme north, and in Labrador. In winter, migrates southward as far as Maine.

Falco Islandicus, Jer Falcon, Rich. & Swains. F. Bor. Amer. v. ii. p. 27.

Gyr Falcon, Falco Islandicus, Nutt. Man. v. i. p. 51.

Iceland or Jer Falcon, Falco Islandicus, Aud. Orn. Biog. v. iv. p. 466. Adult Female.

Iceland or Jer Falcon, Falco Islandicus, Aud. Orn. Biog. v. ii. p. 552. Young Male and Female.