Date of Award

1998

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

First Advisor

James V. Remsen, Jr

Abstract

"Airbirds" are defined as those birds that are adapted to almost constant life on the wing and do not perch, except for breeding and roosting. They use the air as the only medium in which to find and gather food. One taxon meets that definition: the swifts (Apodidae). Foraging zones of airbirds can be segregated in terms of clutch size, commuting foraging distance, nestling period, and nestling feeding rate. This study looked at foraging behavior and nestling diet, incubation patterns and mode of development in cypseloidine swifts, that as a group has extreme life history patterns. In a temperate one-egg clutch cypseloidine species, winged ants comprised 91% of nestling diet. Parents made foraging trips (3--7 h) at early hours and in the afternoon (6--8 h). Morning trips were observed only during the first half of the nestling period. During the second half, adults made one foraging trip per day for about 12 hrs. The morning trips presumably are for feeding the young, whereas the long afternoon bouts are also for self-maintenance. As nestling age increased, so did food bolus mass. Based on a 12 h daylight, a one-egg species neglected the egg 50% of the time and incubated for 29 days. A two-egg species neglected the eggs 32% of the time and incubated for 25 days. Longer incubation and slower growth of the one-egg versus the two-egg clutch might be explained in terms of greater time away from the nest in foraging time. Foraging and incubation patterns in cypseloidine swifts are analogous to procellariiform seabirds. The time scale for cypseloidine swifts is in hours, whereas for procellariiform seabirds, it is in days. Because they face similar constraints with respect to food and nest sites, convergence in their life-history patterns follows. Postnatal growth pattern of Californian and Costarican subspecies of Cypseloides niger were compared. The Costarican subspecies has a longer incubation period, but both had roughly equal nestling periods. Nestlings of the Californian subspecies grew faster, as predicted by the general theory in growth rates. However, it contradicts the rule that smaller-bodied taxa grow faster than larger-bodied ones.

ISBN

9780599213906

Pages

111

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