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Updated: Jun 18, 2026
10:07
Thermal Imaging to Study Stress Non-invasively in Unrestrained Birds
Published on: November 6, 2015
Effects of small increases in corticosterone levels on morphology, immune function, and feather development
Michael W Butler1, Lynda L Leppert, Alfred M Dufty
1Department of Biological Sciences, Boise State University, Boise, Idaho 83725, USA. mike.butler@asu.edu
Physiological and Biochemical Zoology : PBZ
|November 26, 2009
Summary
Simulated chronic stress in American kestrels (Falco sparverius) did not immediately impact nestling development. However, delayed effects on wing length and immune function were observed after stress hormone levels returned to normal.
Area of Science:
- Avian biology
- Endocrinology
- Developmental biology
Background:
- Environmental stressors during development can alter an individual's phenotype.
- Chronic low-level stress is a significant factor influencing wildlife populations.
- Corticosterone is a key hormone mediating the stress response in birds.
Purpose of the Study:
- To investigate the effects of simulated chronic low-level stress on American kestrel (Falco sparverius) nestlings.
- To assess the impact of corticosterone exposure on growth, immunocompetence, and feather coloration.
- To determine if stress-induced changes persist after the stressor is removed.
Main Methods:
- American kestrel nestlings were exposed to simulated chronic stress via corticosterone implants or sham implants.
- Measurements included morphometrics (mass, tarsus, wing length, asymmetry), immune function assays, and feather coloration analysis.
- Effects were assessed both during the exposure period and one week after implant removal.
Main Results:
- No significant differences in morphometrics, immunocompetence, or feather coloration were observed during the weeklong exposure.
- One week post-implant removal, sham-implanted birds exhibited significantly longer wings compared to corticosterone-implanted birds.
- Sham-implanted birds also showed reduced cutaneous immune function relative to the corticosterone-implanted group.
Conclusions:
- Elevated corticosterone levels, even at 2 ng/mL above basal titers, can induce subtle but measurable long-term effects on avian development.
- These findings highlight the potential for delayed consequences of developmental stress on wild bird populations.
- The study underscores the complex interplay between stress hormones and developmental trajectories in birds.
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