Manipulating Individual State During Migration: Carry-Over Effects of Cumulative Stress on Survival

Area of Science:

• Wildlife physiology and ecology
• Stress response in animals
• Conservation biology

Background:

• The stress response is crucial for survival, but chronic stress can impair fitness.
• Long-term effects of cumulative stressors on wild populations' demographics are understudied.
• Previous research often relies on observational data, limiting causal inference.

Purpose of the Study:

• To experimentally investigate the demographic consequences of multiple stressors on greater snow geese.
• To assess the impact of fasting and prolonged captivity during spring migration on survival and reproduction.
• To examine the relationship between stress hormone levels (corticosterone) and demographic outcomes.

Main Methods:

• Female greater snow geese were experimentally subjected to fasting and/or prolonged captivity (up to 4 days) during spring migration.
• Blood samples were collected to measure corticosterone (CORT) levels at various time points.
• Subsequent reproductive success and survival in the following year were monitored.

Main Results:

• Stress-induced CORT levels at release were influenced by pre-experiment body condition, not peak stress response.
• No link was found between stress exposure and subsequent reproductive success.
• Food deprivation exhibited negative carry-over effects on survival in the subsequent year; hormonal response intensity marginally affected survival.

Conclusions:

• Cumulative stressors, such as food deprivation and captivity, can have significant carry-over effects on wildlife survival.
• The intensity of the hormonal stress response plays a role in determining long-term survival.
• Understanding stress physiology is critical for predicting and mitigating impacts on wild populations.