By Victoria Gill Science reporter, BBC News
14 September 2016
A bird so rare that it is now extinct in the wild has joined a clever animal elite - the Hawaiian crow naturally uses tools to reach food.
The bird now joins just one other corvid - the New Caledonian crow - in this exclusive evolutionary niche.
Dr Christian Rutz from St Andrews University described his realisation that the bird might be an undiscovered tool user as a "eureka moment".
He and his team published their findings in the journal Nature.
"I've been studying New Caledonian crows for over 10 years now," Dr Rutz told BBC News. "There are more than 40 species of crows and ravens around the world and many of them are poorly studied.
"So I wondered if there were hitherto undiscovered tool users among them."
Previously, Dr Rutz and his colleagues have reported that New Caledonian crows have particular physical features - very straight bills and forward-facing eyes. The researchers suggested these might be tool-using adaptations.
They then searched the crow family for species with similar features, and Dr Rutz said he quickly realised that the "Hawaiian crow was the perfect candidate for further investigation".
Though it will now be something of a scientific celebrity, the Hawaiian crow has recently been rescued from the very brink of extinction.