Stress in the Red-cockaded Woodpecker: Hormonal Mechanisms of Reproductive Suppression in Helper Males and Impacts of Military Training Activities

The measurement of stress hormone levels in wild free-living animals is becoming an increasingly effective method for examining proximate mechanisms of animal behavior and the physiological impacts of human activities on wildlife. In these studies I measured plasma levels of the stress hormone corticosterone in the endangered red-cockaded woodpecker (Picoides borealis) to determine their role in the reproductive behavior of individuals in this species, and whether they are affected by human disturbance. In chapter one, I provide an introduction to the vertebrate stress response and I describe the natural history of the red-cockaded woodpecker. In chapter two, I compare corticosterone and reproductive hormone levels between breeding males and helper males to examine hormonal mechanisms of reproductive suppression in helper males. No hormonal differences existed between breeding and helper males. However, baseline corticosterone levels were lower in all males living in groups with two or more helper males, suggesting that male helpers reduce the workload of all other group members. In chapter three, I compare corticosterone levels between birds living in clusters subject to two different training restriction regimes on a military installation. Males living in clusters without training restrictions had lower baseline corticosterone than those living in clusters with training restrictions, suggesting that males habituate to chronic disturbance by downregulating baseline corticosterone levels.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Biology

Department dc:contributor.department

Biology

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2007

Author dc:creator

• Malueg, Amanda Leah

Chair dc:contributor.committeechair

• Moore, Ignacio T.

Committee members dc:contributor.committeemember

• Walters, Jeffrey R.
• Haas, Carola A.

• stress
• corticosterone
• cooperative breeding
• human disturbance
• Picoides borealis

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-09172007-214506

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/35091