SEASONAL AND GEOPGRAPHICAL VARIATION IN DOWNY WOODPECKER (PICOIDES PUBESCENS) METABOLISM AND THERMOREGULATION
File(s)
Date
2012-10Author
Cousineau, Christopher J
Advisor(s)
Cooper, Sheldon
Metadata
Show full item recordAbstract
Downy woodpeckers (Picoides pubescens) are small, non-migratory, nonpasserine
birds. Non-migratory birds that overwinter in cold temperate zones are
exposed to energetically costly conditions during winter. These conditions include
decreased daytime for foraging, long nights requiring increased periods of fasting, and
decreased food availability. These birds will also be exposed to extremely cold
temperatures in winter months. To survive these conditions birds must go through a
process of season acclimatization. In birds, seasonal acclimatization has been found to
mainly focus on adjustments in metabolic rates such as basal metabolic rates (BMR) and
summit metabolic rates (Msum) when under cold stress. Another possible factor in
seasonal acclimatization is the substitution of heat produced from locomotive muscle
activity for thermoregulatory heat. Despite the impact that metabolic rates have been
shown to have on seasonal acclimatization, there has been little research into geographic
variation in metabolic rates and ventilation of birds. The purpose of this study was to
observe seasonal variation in metabolic rates and ventilation variables between
Wisconsin Downy woodpeckers and South Dakota Downy woodpeckers. A secondary
goal of this study was to observe seasonal variation in thermoregulatory substitution in
Wisconsin Downy woodpeckers.
Open-circuit respirometry was used to measure oxygen consumption (VO2) and
ventilation in seasonally acclimatized Downy woodpeckers. Metabolic rates and
ventilation were measured under cold stress using a helox (~79% helium and ~21%
oxygen) gas mixture and at thermoneutral zone (TNZ) conditions. Foraging activity was
also measured using an infrared camera and a closed-circuit television monitor. During
foraging trials activity was measured by time spent foraging on a peanut feeder placed
into the metabolic chamber. Heat of activity was measured using a thermocoupler when
birds were foraging and when feeders had been removed and birds were at rest.
Wisconsin Downy woodpeckers showed a significantly higher BMR and Msum in
winter compared to summer. South Dakota Downy woodpeckers had a significantly
higher Msum in both summer and winter compared to Wisconsin Downy woodpeckers.
Wisconsin Downy woodpeckers had significantly higher EO2 in the winter compared to
summer during both BMR and Msum testing. Thermoregulatory substitution was
observed in Wisconsin Downy woodpeckers during summer.
Subject
Birds behavior
Picoides
Downy woodpecker
Permanent Link
http://digital.library.wisc.edu/1793/65114Description
A Thesis Submitted In Partial Fulfillment of the Requirements For the Degree of Master of Science - Biology