Feeding waterfowl: killing with kindness

IT IS NOT uncommon to witness the excitable frenzy that accompanies feeding waterfowl white bread. Our intentions are harmless, but increased consumption of white bread in waterfowl can cause the metabolic disease or deformity known as ‘angel wing’. As with everything in life, too much of anything can be problematic.

Angel wing can be due to genetic defects, calcium, manganese, or vitamin D deficiencies and unbalanced diets due to human intervention. A diet that is not nutritious can cause birds to have an accelerated growth rate in flight feathers. This increased weight on juvenile wings applies pressure on flight muscles, and the carpal joint is unable to provide the support needed. Gravity encourages the wing to hang and twist outwards – an irreversible deformity that reduces the ability to evade predators and is problematic for migratory wildfowl (i.e. Canadian geese).

Angel wing is asymmetric, damaging primary flight feathers on mainly the left pinion but can affect both wings. Wings appear ‘stripped’, leaving only the shaft and the odd

Image: Wikimedia commons

barbule to protrude from the remiges (symmetrical pennaceous flight feathers) and around the carpal joint. There are three environmental factors to be considered when caring for birds in captivity to reduce the risk of development of angel wing. Increased time to eat due to artificial lighting leads to increase growth rate and insufficiently sized enclosures result in reduced exercise of flight muscles.

Excessive incubation of enclosures reduces the amount of ATP used to keep warm; this excess ATP is reallocated and increases growth rate. Although angel wing has the potential to be fatal in semi-wildfowl, if administered early enough, treatment can be effective. Feathers can be taped up to the wing for three to seven days maximum and it is important to note that this method is most effective in juveniles. Levels of protein and carbohydrates should be reduced. Wildfowl/waterfowl are grazers and natural grazing should be encouraged. If grazing grounds are insufficient, placing food bowls distances apart will also act as a preventative method. If necessary, an osteotomy to realign of the distal carpometacarpus by insertion of a pin into the radial metacarpus can be performed to help correct the deformity. The last option is pinioning. This is controversial when used to restrict flight in domesticated birds as an alternative to surgery (there is always risk when putting any animal under anesthetic).

In many parks and areas open to the public, there are signs prohibiting the feeding of wildlife. Bans on feeding wildlife have been implemented to protect them, reduce human dependency, defend against invasive pest species like rats, and encourage natural behaviour. Feeding wildfowl can result in overcrowding, as everyone rushes to get the tasty morsels. Overcrowding puts that particular patch of habitat under stress due to competition and contamination of resources, leading to outbreaks of disease and a weakened immune response. The culture of feeding wildfowl and waterfowl causes flocks to delay or forfeit their migration. This can be fatal on population numbers as juveniles are not able to learn migratory routes.

If there is not a ban in certain areas and you would like to feed the wildfowl/waterfowl or any other wildlife, it is important to research and get advice from nature centres and feed them food suited to their needs. This will help prevent unintentional harm that could affect the health of the animals. This advice is applicable to all forms of wildlife, even in your own garden, as feeding birds during the winter can be lifesaving, but the wrong seeds can be fatal too. Don’t be afraid to approach wildlife centres to ask for advice. Do your bit and prevent, preserve, protect, and keep the wildlife wild.

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