Two species of bats are now regionally threatened in Auckland, according to the council.

The pekapeka-tou-poto, the northern lesser short-tailed bat, and pekapeka-tou-roa, the long-tailed bat, have been assessed as vulnerable in the region by the council and a panel of bat experts.

It is the first regional conservation status assessment of the species using the Department of Conservation's threat classification system.

Pekapeka, which are only the size of a thumb and the weight of an AA battery, are New Zealand's only native land mammals.

The short-tailed bat is only known to live on Te Hauturu-ō-Toi/Little Barrier Island in the Auckland region, while the long-tailed bat has been recorded more widely across the region.

Despite the latter being recorded more widely and Little Barrier Island being free of introduced mammalian predators, the council says they are still at risk due to habitat loss, other human impacts, and climate change.

Councillor Richard Hills, who is chair of the planning, environment and parks committee, says this assessment will help the council prioritise conservation efforts.

Auckland Council regional biodiversity adviser Jacinda Woolly says more information is needed on the species to be able to effectively protect them.

"We need to understand more about their roosting areas, flyaway and feeding areas and how they're using the whole landscape so further protection measures can be employed.

"If their key threats are left unmanaged at roost sites, their population will continue to decline, and the potential rate of that decline is of concern."

The council says there's also increasing interest from mana whenua and community groups, who have been monitoring pekapeka.

In 2021, the long-tailed bat was crowned bird of the year in a popular competition where the public votes for their favourite birds.

The Conservation Status Report programme of work delivers on council's obligations for regional biodiversity management under the 10-year Budget 2021-2031.

-RNZ.