Avian cholera in eider ducks in Maine

Area of Science:

• Avian pathology
• Wildlife disease ecology
• Ornithology

Background:

• Avian cholera, caused by Pasteurella multocida, frequently impacts common eider populations in Maine.
• Outbreaks typically occur during early summer.

Purpose of the Study:

• To investigate the patterns and potential causes of avian cholera outbreaks in common eiders.
• To identify factors contributing to high mortality rates in specific demographic groups.

Main Methods:

• A seven-year study period was utilized to collect data on avian cholera outbreaks.
• Observations focused on mortality patterns, particularly in relation to nesting and incubation behaviors.

Main Results:

• Over 90% of avian cholera-related losses were observed in incubating female common eiders.
• Weakened physiological condition, stemming from fasting during incubation, is a potential contributing factor.
• High nesting densities may exacerbate disease transmission and mortality.

Conclusions:

• Incubating female common eiders are highly vulnerable to avian cholera, likely due to physiological stress.
• While carrier birds were identified, the primary source of Pasteurella multocida requires further investigation.
• Management strategies should consider factors influencing female eider condition and nesting behavior.