The offspring of hundreds of thousands of breeding ibis at Middle Lake rookery near Kerang were this week the victims of local flooding.

The lake's water level increased significantly over the past three days, inundating the lignum nests inhabited by the water birds.

Veteran conservationist, Mr Des Thomas said that flooding caused a repeat of past tragedies which have killed young birds and forced adult birds to abandon their eggs.

Mr Thomas and Mr Fred Wilkinson have made constant visits to the rookery in recent weeks after new water flows stimulated breeding.

They said that the devastation was an indictment on the failure of the Department of Conservation and Natural resources to adequately manage the rookery.

"If you or I shot an ibis, we would be fined, yet the people who are supposed to manage the birds are unable to learn from past history," Mr Thomas said.

Local DCNR officials were unavailable for comment.