Stress physiology during life history transitions in Laysan Albatross

Rachel S. Sprague, Ph.D. Wildlife Biology
Advisor: Creagh W. Breuner

Funding Source(s):
National Science Foundation
U.S. Fish & Wildlife Service
(Kauai National Wildlife Refuge Complex and Midway Atoll National Wildlife Refuge)
Kilauea Point Natural History Association
Society for Integrative and Comparative Biology
Five Valleys Audubon Society
Sigma Xi
American Ornithological Union
University of Texas at Austin

Project Duration: 2004-2008
UM Project Affiliation: WBIO

Objectives:

I am interested in the role of glucocorticoid (GC) hormones as a proximate mechanism mediating life-history transitions. Specifically, I am investigaging the action of GC hormones in a long-lived seabird with an extreme life-history strategy, the Laysan Albatross (Phoebastria immutablis):

1.  How do GC hormones and binding proteins change during long (2-3 week) incubation fasts?
2.  How does the GC stress response change with age?
3.  How do age, body condition, GC physiology, or environment affect parental behavior?

Progress and Status:

All sample collection from birds in the field and data analysis of samples in the lab is completed. We have found exciting relationships between age/experience, stress physiology, and behavior in adult albatross provisioning their chicks. Glucocorticoid hormones tend to promote self-maintenance activities (e.g. nest abandonment) at the expense of reproduction and usually rise in situations of food deprivation, social stress, or unpredictable environmental events (to name a few).

We have found that generally, stress hormones rise when body condition declines. Binding proteins (CBG) bind GC hormones in the blood and may restrict access of those hormones to receptors in tissue. Surprisingly, binding proteins also rise during incubation fasts as birds lose mass (generally thought to decline when body mass falls). This may help protect adults from the negative effects of elevated GC hormones on reproduction.

In this long-lived species, age appears to be an important factor influencing both physiology and behavior. Older parents appear to have a lower GC stress response, possibly making them less likely to abandon their current reproductive effort than younger birds. In 2007, older birds and birds in good body condition made foraging trips that resulted in heavier chicks. Interestingly, the types of trips they made were not predicted based on previous research from the Southern Hemisphere. These Northern Hemisphere birds may face ocean conditions that lead them to different foraging strategies than their southern counterparts.