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The Aerial Capture of a White-throated Swift by a Pair of Falcons

Lee W. Arnold

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The Aerial Capture of a White-throated Swift by a Pair of Falcons.-On June lo, 1942, while camping at Horse Tank, a permanent desert watering tank within the boundaries of the Kofa National Game Range in the Castle Dome Mountains, about 50 miles northeast of Yuma, Arizona, I had occasion to witness a contest between two masters of flight-a large falcon and a White-throated Swift (4bomutes sexatis). [On the basis of color, the falcons were identified as Duck Hawks (Folco pevegrinzcr) , but since no specimen was obtained, the writer feels that a positive record of this species should not be claimed].

When first sighted at about 100 feet above the tank, the hawk was pursuing the swift. The falcon was about ten feet behind the smaller bird and both were apparently straining every muscle in an effort to gain more speed. As though in an attempt to discourage its pursuer, the swift made an almost perpendicular dive. Although the falcon followed the smaller bird down almost to the ground, it could not seem to shorten the distance between itself and its prospective prey. At about ten feet from the ground the swift pulled out of the dive and strove to gain altitude. The falcon followed closely behind it. Judging from this performance, I assumed that the race would be a fair one. However, just as the swift was regaining altitude, another, smaller falcon of the same species came into view a little above and behind the two birds I had been watching. This smaller falcon, probably the male of the pair, swooped down upon the swift from behind, but a slight change in course by the swift caused the hawk to miss its mark. The larger falcon, presumably the female, continued its dogged chase close to the tail of the swiit while the smaller falcon circled and gained altitude. After several moments, the smaller hawk again dove at the swift. This time it hit its mark squarely. When last seen, the pair of hawks was flying off into the distance. The smaller hawk was carrying the swift in its talons.

It will always remain a question in my mind whether or not the larger hawk could have mastered the situation without the cooperation of its apparent mate. Of particular interest was the fact that the two falcons chose to capture a bird as small and agile as a White-throated Swift within a few feet of a desert tank which at that time was frequented daily by several hundred White-winged Doves (Melopelia asiatica), Mourning Doves (Zenaidura macroura), and Gambel Quail (Lophortyz gambelii).-LEE W. ARNOLD, Arizona Game and Fish Commission, Phoenix, Arizona, August 4,1942.

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