Feather extension helps native hawk-eagle fly again

When a bird loses feathers and can no longer fly, vets in Singapore can use a special "feather extension" technique to restore its wings and return it to the sky.

This process, known as imping, was used by vets at the avian hospital in Jurong Bird Park on a changeable hawk-eagle on Jan 20.

The nationally threatened raptor was rescued by the National Parks Board (NParks) on Jan 7, when it was found with severe thermal damage to all the important flight feathers on its wings and tail, and unable to fly.

It was then taken to the hospital for closer examination, and was found to be in good health, apart from its burnt feathers that were suspected to have been singed by hot gas or flares.

A spokesman for the park said: "While birds will naturally grow new feathers through their moulting cycle, it could take up to 12 months for the eagle to fully regrow its feathers and be able to fly again."

This is an issue because keeping a wild bird in captivity comes with risks, such as causing unnecessary stress to the bird, or the bird becoming overly dependent on human care.

"The veterinary team decided to imp its wings and tail feathers to help speed up the bird's release to the wild," the spokesman said.

Imping, which is thought to be centuries-old, with roots in ancient falconry, involves joining the remains of a damaged feather to a new feather by its shaft.

The new feather is affixed by inserting an imping needle - which is made out of bamboo or other materials - and securing it using an adhesive.

Dr Ellen Rasidi, the veterinarian at Jurong Bird Park, compared this practice with humans getting hair extensions.

Dr Rasidi said: "However, unlike hair extensions, we have to be extra meticulous in ensuring that each individual replacement feather is carefully trimmed, measured and arranged in the right position to match the patient's original feather length and orientation as much as possible."

This is because fixing feathers incorrectly and at wrong angles will affect the bird's ability to fly.

Also, feathers donated have to preferably be from the same species.

The changeable hawk-eagle ended up having more than 50 of its feathers on its wings and tail imped successfully with bamboo chopsticks.

After adapting to its new feathers well, the eagle took off a day later on Jan 21.

Based on a satellite tracking device attached to the imped tail of the eagle prior to release, the bird has since flown at least 10km away from the release site.

The tracking device is expected to be shed along with the bird's imped feathers as it grows new feathers through its moulting cycle, with both these man-made inventions fulfilling their purpose.

For fixing the feathers, Jurong Bird Park approached animal protection charity Acres and NParks for suitable donor wings from changeable hawk-eagles that had died from severe injury or disease.

Acres fortunately found a dead changeable hawk-eagle on the road on Jan 11, and donated it to the park.

Mr Kalai Vanan, the co-chief executive of Acres, said that while it was a suitable donor, not all carcasses qualify to be feather donors, which leads to their rarity.

Mr Kalai said: "We find suitable donors only once in a while because not only are such findings dependent on chance, but these carcasses also need to be assessed for their feather quality.

"Only adult birds with fully grown feathers can be used. The feathers must also not be brittle and not be infested with parasites like mites."

Acres started a feather bank in the middle of last year to ensure that there is a stock of donor wings for rescued birds that need them.

About 30 sets of wings and tails of different bird species have been frozen for use at a later date.

Dr Venisri Raj, senior veterinarian at Acres, said: "We don't always have feathers for some species, and sometimes, waiting for a good donor could mean a longer time in captivity for the bird that needs it.

"So when we stumble upon a carcass with perfect feathers, we definitely try to preserve it."