Ngāpuhi leader Sonny Tau failed to take the appropriate steps before trying to take kererū from the South Island, a conservation organisation says.
Mr Tau is being investigated by the Department of Conservation after being found with kererū in his possession.
The New Zealand Conservation Authority's role is to advise the Minister of Conservation and the Director-General of Conservation on environmental issues.
Its chair, Warren Parker said tangata whenua can apply for permits to take protected species, such as kererū, for cultural purposes on a case-by-case basis.
Dr Parker said permits can be authorised if the preservation of the species is not affected, tāngata whenua support the application, and it is consistent with the relevant regulations.
He said it also had to be consistent with the purposes for which the land involved is held and there must be an established tradition of the intended customary use.
Dr Parker said as far as he understood, an application wasn't made by Sonny Tau.
He said it was disquieting that a leader did not respect the rules.
"It's particularly concerning in this case because the expectations and guidelines for accessing kererū for customary rights is pretty clear and the circumstances in which a special case can be made are specified so for a senior leader to not be cognisant of that and respectable of that is a concern."
Dr Parker said Mr Tau has been put under pressure by the public.
"The mood of the public and the awareness of the public in broad terms, iwi and Pakeha and other ethnic groups recognise the special nature of this bird and so that brings to bear some community pressure that this is not acceptable."
Dr Parker said he understood that in some cases, such as when a kuia or kaumātua are very ill, they would want to exercise their customary rights and taste kererū.