Food, foraging, and timing of breeding of the black swift in California.: An article from: Wilson Bulletin

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From the author: The nestling diet and breeding seasonality of the Black Swift (Cypseloides niger) were studied in southern California 1990-1992. The peak (40%) of egg laying was in mid-June and the peak of fledging (60%) was mid- to late August (n = 87 nests). Winged ants comprised 91% (n = 1179 prey items, 10 boluses) of nestling diet. Three main prey size classes were found: 6, 8, and 13 mm. Food bolus mass increased and number of trips per day to feed the nestlings decreased with nestling age. The parents made short and long foraging trips during early morning hours and long trips from early to late afternoon. Short trips were observed only during the first half of the nestling period. During the last half of the nestling period, parent swifts made a single foraging trip per day that lasted about 12 hrs. Perhaps the short foraging bouts are for feeding the young, whereas the long foraging bouts are not only for feeding the young but also for parental energy storage. The single foraging bout, during the mid- and late nestling period, might also serve to store fat for migration by the adults.

Citation Details
Title: Food, foraging, and timing of breeding of the black swift in California.
Author: Manuel Marin
Publication:Wilson Bulletin (Refereed)
Date: March 1, 1999
Publisher: Wilson Ornithological Society
Volume: 111 Issue: 1 Page: 30(8)

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