This species of parrot was believed to be extinct until some were recognised in the Bolivian savannah in 1992.
As such, endangered Lily and Margot are “ambassadors” for their species, London Zoo has said.
At the zoo, their diet and health is monitored by experts.
With help from local residents and Westminster Council, the Regent’s Park zookeepers have been combing the area for sightings.
With no luck, they are now appealing to the wider public.
