By Alister Doyle, Environment Correspondent

Oslo - Australia's orange-bellied parrot and the Florida panther are in an exclusive but growing club - rare species getting costly protection even as the world faces what may be the worst wave of extinctions since the dinosaurs.

Governments in rich nations sometimes write virtual blank cheques to protect exotic animals - even as thousands of less glamorous creatures and plants slide silently into oblivion.

Many experts say it is impossible to set a ceiling on the value of a species and that willingness to pay may be widening, posing risks for businesses like mining, industry or logging that affect the habitats of rare animals or plants.

"Willingness to pay is related to wealth," said Don Coursey, a professor in public policy studies at the University of Chicago.

"As world wealth tends to grow, willingness to pay to protect species is growing even faster."

Coursey once wrote a report estimating it cost $4,9-million (R25-million) per creature to protect the endangered Florida panther - the most expensive US protection scheme and more than many insurers pay for a human life.

The California condor was second at $1,6-million (about R7-million) per bird.