Infection and mortality in captive wild-trapped canvasback ducks

Area of Science:

• Avian pathology
• Wildlife health
• Infectious diseases in animals

Background:

• Wild-trapped canvasbacks (Aythya valisineria) were housed in confined pens for study.
• Confinement conditions may impact avian health and disease susceptibility.

Purpose of the Study:

• To investigate the causes of mortality in confined canvasbacks.
• To assess the role of infections and malnutrition in captive wild birds.

Main Methods:

• Monitoring of wild-trapped canvasbacks over a period of 158 days in open-water pens.
• Necropsy and microbiological analysis to identify causative agents of mortality.
• Comparison of survival rates between confined birds and those released into larger ponds.

Main Results:

• Heavy mortality was observed in penned canvasbacks, with deaths occurring between 21 and 158 days post-confinement.
• Infections identified included Aspergillus fumigatus, Escherichia coli, Staphylococcus sp., Streptococcus sp., Klebsiella sp., Enterobacter sp., and Plasmodium sp.
• Canvasbacks released onto large ponds exhibited higher survival rates during the study period.

Conclusions:

• Confinement stress likely reduced the immune resistance of canvasbacks, predisposing them to fungal, bacterial, and malarial infections.
• Malnutrition and infectious diseases were primary causes of mortality in this captive wild bird population.
• Larger, less restrictive environments appear more suitable for maintaining the health of wild-trapped canvasbacks.