A warning to the Government that there could be serious consequences if it doesn't increase the funding going to the Department of Conservation.

DOC staff are taking industrial action this week, saying they feel undervalued, with the Government trying to do conservation on the cheap.

1500 staff have said they will not be doing over-time, answering phones or emails.

The move comes after the latest offer from DOC was rejected by 95 percent of union members.

Green Party conservation spokesperson Kevin Hague says it's a major red flag.

"We have seen those shortcuts being taken in the past with events like cave creek and we've most recently had another bridge collpase."

Hague said DOC's work is too important to underfund it.

"If we do not preserve the unique species to this country then they will cease to exist on the planet. That's a terrible consequence and one that could be avoided if Government were to actually put money in."

Public Service Association National Secretary Erin Polaczuk said workers feel the whole department is under-funded, and the results of negotiations a couple years ago made little difference.

"Almost half of them didn't get any pay rise whatsoever and they've had enough. They feel undervalued, they feel that the work of DOC is undervalued by the Government, and they feel really passionately about their work and think that they're worth more."