In a park near Croydon in south London is a notice saying that white bread causes the geese to have distorted wings. There are two geese with this problem in the park. How is white bread harmful to geese and does it really lead to wing damage?
• Canada geese may develop what is commonly known as angel wing, caused by excessive dietary protein when waterfowl are under 8 weeks old. White bread alone is not necessarily responsible – the source could be high-protein foods such as cheese in sandwiches.
The furthest joint of the wing, the carpus, is the last to ossify in young birds. Excess protein is deposited here, and this makes the carpus prone to deforming under the weight of the growing primary feathers, which are filled with blood. The blood is later reabsorbed, leaving empty quills.
In an adult with angel wing, the wing tip and ...