A Waikato wetland sanctuary is reintroducing rats to try to drive out birds fouling a prized lake.
The move is a last resort to try to scare off half a million sparrows and starlings that have found a safe spot to roost overnight around pest-free Lake Rotopiko.
National Wetland Trust executive officer Karen Denyer says the non-native birds poo so much they are changing the ecosystem and endangering the water quality.
She spoke to Corin Dann.
