A police spokesperson said a complaint has been made in relation to anti-1080 protesters leaving dead native birds on the steps of Parliament.
Police inquiries into the matter are ongoing they said.
Acting director general for the Department of Conservation Mervyn English said New Zealand has a predator crisis and 1080 is needed.
"There is significant science behind the safe use of 1080 and its effectiveness in reducing predators that kill our native wildlife in the wilderness.
"1080 is saving our birds, plants and insects. We have a choice between rats, stoats and possums or our unique native species. I choose protecting our taonga," he said.
Mallard said forensic experts say the birds were killed by blunt force trauma.
"It has been confirmed to me that kererū and weka, amongst other protected native species, were among the dead birds deposited on the steps of Parliament during the course of a protest action," Mallard said in statement.
"The kereru appears to have been killed by bludgeoning. As a protected species under the Wildlife Act 1953 it is an offence to kill any absolutely or partially protected wildlife. It is also an offence to buy, sell or otherwise dispose of, or have in his or her possession any absolutely protected or partially protected wildlife. Individual persons are liable for an imprisonment term not exceeding 2 years or a fine not exceeding $100,000, or both."
"I am supportive of reasonable protest action at Parliament and believe in the rights of individuals and groups to voice their opinion through protest, but I cannot condone illegal activity committed as part of a protest action on the grounds of Parliament, and therefore a complaint has been laid. I also personally find it regrettable that children were encouraged to be involved in this illegal activity."
English also said there were eight incidents were DOC staff were approached by anti-1080 supports which is more than usual.
"There have been eight incidents where staff have been physically confronted, abused and harassed.
"There have been seven incidents of abusive phone calls or emails. There have been countless incidents of social media threats and abuse.
"Threats and abuse are completely unacceptable and people attacking DOC staff can expect to see the cops on their doorsteps," English said.