TORONTO -- Ontario's environmental watchdog warns the government "needs to walk the walk" to protect the province's biodiversity following a 20 per cent drop in the moose population over 10 years and a steep decline in several bat species.

Environmental commissioner Dianne Saxe says the Liberals need to put words into action to combat wildlife declines, control invasive species and implement better forest fire management - by letting more fires burn.

Saxe says the populations of eight of 27 amphibian species in Ontario are at risk of being lost from the province, while four of eight bat species are now endangered because of an aggressive fungal disease known as white nose syndrome.

In her annual report, the commissioner says invasive species such as Asian carp, zebra mussels, the emerald ash borer and even feral wild pigs can disrupt or destroy entire ecosystems.

Zebra mussels alone are estimated to cost Ontario over $75 million a year as they clog intake pipes at water treatment plants and power generating stations on the Great Lakes.

Saxe gave the government high marks for passing a new invasive species act last year, but wonders if it will work because "most of the hard front-line work is still left to municipalities, conservation authorities and private landowners."