We provide information on population parameters in colonies of the biscutate swift from southern Brazil using the capture—recapture technique. We captured 1020 adults, 233 nestlings and 25 subadults, totaling 1278 marked birds. Models with capture probabilities varying with time and individual animal (CAPTURE program), and with constant survival and time-dependent recapture (MARK program) best fit the data. The results of both methods were relatively similar because the models selected suggested that mortality, recruitment or movement events were unimportant. Population sizes were estimated to be between 187 and 1902 individuals in the four colonies studied. The estimated mean annual survival for the species was 0.88, a value corresponding to an average longevity of 18 years. Little individual movement occurred among the colonies; the largest displacement observed was 120 km. One of the colonies did not display the same capture pattern as that of the others, probably due to space conflicts or shelter occupation time. Our data show that in southern Brazil biscutate swifts do not migrate, possibly because food availability is more constant throughout the year than in other regions (southeast and northeast) where migration occurs.
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Vol. 47 • No. 2