Nigel Sargent, EPA manager of regional operations, said results from initial tests show that the birds, primarily cockatoos and corellas, have consumed the insecticide omethoate.

“This is used on a variety of agricultural crops and fruit trees for insect pest management,” Mr Sargent said.

He said the results came from analysing a number of dead birds that were sent to Office of Environment and Heritage laboratories as part of the investigations.

Initial autopsies, which showed oat grain in the crops and signs of toxin.

The investigation came after residents initially reported and took a number of the dead birds to Murrumbateman Veterinary Clinic in early July.

Veterinarian Dr Iva Velevska said the clinic is continuing to work with the EPA in its investigation. Since mid July, Wildcare in Queanbeyan has been collecting the birds from the clinic for rehabilitation.

Maryanne Gates, bird coordinator at Wildcare, said she initially contacted the Yass Police Station.

“They advised me to follow it up with the EPA to investigate and confirm that poisoning was involved,” she said.

Ms Gates said the police did conduct extra patrol in Murrumbateman in mid July.

Since July 25, Wildcare has had 11 cockatoos, two corellas, one galah and one raven in its care.

“I had about 30 birds and I’d say there’s many that have died,” Ms Gates said.

“The ones that came in last weekend are now well enough to have been moved to an aviary to continue their recovery,” she said.

“We’re not convinced its stopped. There could be other bodies and people aren’t seeing them.”

At this stage, the EPA has not determined if the poisoning was deliberate. The misuse of pesticides is an offence in NSW and heavy penalties apply, including fines up to $120,000.

To provide information that may assist the EPA, please contact its environment department on 131555 or epa.nsw.gov.au/feedback.