Devastated: Geckos living in the area would have been wiped out. Photo / George Novak.
Mauao Area Wildlife Trust chairwoman Julia Graham said watching the fire was like "watching my house burn down".
She was "just holding my breath" that it did not reach the north west side.
"That would have been absolutely devastating as that is where our main [penguin] colonies are."
"Any loss of habitat and anything that happens on Mauao is a tragedy because it's such a special part of our community and country. It's such an iconic place."
The fire would have been in the middle of the Pacific gecko territory so the reptiles up in that area would have been wiped out.
Late nesting tuis would also be affected, she said.
Any fire was devastating for the wildlife on Mauao as the loss of forest leads to erosion and less habitat for the birds, she said.
The fire would have a large impact and it would take years for Mauao to recover.
Reforestation would need to be done or else the mountain would start to erode but the trust would have to wait until at least April to start doing that because more rain in the cooler months would be needed.
Funding would be needed for the trust to be able to start reforestation work.
New plants and trees would have to be grown then replanted in the affected area, she said.
Mrs Graham said firefighters did an awesome job containing the blaze when it broke out.
Long-time Mount resident and conservationist Allan Goodhall said the fire highlighted how Mauao was such a fragile and important environment.
"It is so important in so many ways to so many people."
Whether they were walking around the base track or up and down Mauao, whether they were members of the wildlife trust, or people working out - Mauao was so well used, he said.
"Luckily it was no where near the extent of the 2003 fire."
Mauao Area Wildlife Trust
• The Mauao Area Wildlife Trust is a legally constituted trust and is open for anyone to join. It was established in 2013 after a range of issues were discovered impacting native flora and fauna species prior to, and during monitoring of, little blue penguin and grey-faced petrel colonies affected by the Rena oil spill in 2011.