The Long-tailed bat is now more endangered than the kiwi, kōkako and whio.

The city's critically endangered bat population could disappear altogether if a new development goes ahead unplanned.

The Department of Conservation recently elevated the threat status of the North Island long tailed bat from vulnerable to critically endangered.

Numbers in Hamilton are difficult to determine said Kessels Ecology senior ecologist Wiea​ van der Zwan who works with Project Echo.

Researchers have found the bats like mature trees in Hamilton's gully system with the greatest densities found at the southern end of the city.

But that puts them directly in the path of the new Peacocke development and the Southern Links roading project.

"Because they hang out in those very vulnerable areas like the gullies that are being developed, because we need more houses, all their habitat is going away, being chopped down or fragmented," van der Zwan said.

As a result, the bats will either find new habitat or begin "disappearing altogether".

The North Island long tailed bat population faced a major decline in numbers from 2012 vulnerable status. It is now more prone to extinction than kiwi, kōkako and whio, according to DoC.

"It's very significant," van der Zwan said. "It's the highest level of threat ranking that a species can have before it is extinct."

Van der Zwan briefed Hamilton City Council on managing the bat population with the threat of urban expansion approaching on Thursday.

She called for a long term strategy to plan future development in the city around habitat protection for the bat and a plan to manage tree felling.

And she wants a strategy around a huge threat to the bat - the city's rat population after several years of good breeding conditions.

"It is a great thing for a city to say we've got this critically endangered species in this city among all of this development that is going on," van der Zwan said.. "Being able to say that as a growing city I think is very special and I think Hamilton is pretty unique in that way

Hamilton City councillor Paula Southgate said large scale developments need to be planned well ahead to help protect bat habitat.

"The key is to get it integrated into the planning around new development, not put in as an afterthought, so we can protect the bat from the get-go rather than deal with the consequences of disturbing bat habitat afterwards."