More info from https://www.beautyofbirds.com/angelwing.html:
"Causes:
The disease manifests as an incurable anatomical condition which is acquired in young birds.
"Causes:
The disease manifests as an incurable anatomical condition which is acquired in young birds.
- Dietary Factors: May be caused by a high-calorie diet, especially one high in proteins and/or low in vitamin D, vitamin E and manganese, one or both carpus (wrist) joints are retarded in their development relative to the rest of the wing
- Canada geese fed high protein levels (20%) developed the condition more frequently than those fed lower protein diets (Ref. 1984 Kreeger, T.J. and Walser, M.M. Carpometacarpal deformity in giant Canada geese [Branta canadensis maxima Delacour] 20 245-248)
- Domestic breeds, which have been bred for rapid weight gain, appear more susceptible.
- Growth Factors: Thought to be related to excessively fast growth in relatively slow-growing temperate and tropical species. Rapid growth of flight feathers (primaries: longest wing feathers - and secondaries: shorter, upper "arm" feathers), exceeds the development of the supporting tissues of the wing.
- Temperate and tropical species are naturally slower growing and appear to be more susceptible. This condition has not been reported in species which breed in the high Arctic and have naturally very high growth rates.
- Incubation: A possible role of incorrect incubation conditions and/or hatching problems has also been suggested.
- Injury: Mechanical damage to the wing may precipitate the problem in some cases.
- Genetics:
- Males may be more susceptible than females.
- It is also possible that the cause could be genetic, as the same breeding pair can produce several Angel Wing chicks over many broods"
