What can lead to sour crop in a bird?

Having a large meal when at the low end of their flying weight can lead to sour crop in a bird because it can interfere with normal digestion. When birds are close to their lower weight limit, they may overeat due to hunger or instinct. If a bird consumes more food than its digestive system can handle, particularly when it is not at its optimal weight, it can result in a slow transit time for food through the digestive tract. This sluggish movement can create a favorable environment for bacterial fermentation, leading to sour crop.

This condition is characterized by the fermentation of food, which can produce gases and acidic contents, resulting in a foul-smelling crop. Proper weight management and feeding—ensuring birds are adequately nourished but not overfed, especially at lower weights—are crucial parts of care to prevent this condition.