Type of Document Master's Thesis Author Harding, Sergio R. III Author's Email Address firstname.lastname@example.org URN etd-91597-204823 Title The Dynamics of Cavity Excavation and Use by the Red-Cockaded Woodpecker (Picoides Borealis) Degree Master of Science Department Biology Advisory Committee
Advisor Name Title Haas, Carola A. Jenssen, Thomas A. Walters, Jeffery R. Committee Chair Keywords
- red-cockaded woodpecker
Date of Defense 1997-09-25 Availability unrestricted AbstractQuantification of cavity excavation produced strong empirical support for the
ecological constraints model for the evolution of delayed dispersal in the cooperatively
breeding red-cockaded woodpecker. The long times required for cavity excavation select for competition over
breeding vacancies in established territories and against excavation of cavities in
unoccupied habitat. Duration of excavation varies between woodpecker populations, but
may require over 13 years in longleaf pine and over 10 years in loblolly pine. Duration of
excavation is extremely variable. Much of the variation is due to variation in effort by
excavating woodpeckers, which is in turn partially related to the need for new cavities in relation
to the number of available cavities on a territory. An average of only 11 % of an
individual's time budget is devoted to excavation, and only one individual per group
makes significant contributions to excavation. Once completed, cavities are used for
periods that may exceed fifteen years. Cavities in longleaf pine are used for significantly
longer periods than cavities in loblolly. Whereas cavities no longer used as nests are
abandoned altogether in loblolly, they are still roosted in for many years in longleaf.
Final abandonment of longleaf cavities appears to be related to cavity loss.
Quantification of cavity turnover revealed that three of the study populations were stable
in cavity numbers over the study period, while a fourth underwent alarming declines.
The continued use of restrictors and artificial cavities, and the protection of old-growth
upon which the woodpeckers depend for excavation, are recommended.
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