The Grey-faced Petrel Project was New Zealand’s longest running mainland seabird project [1990-2013].
About 500 birds use the colony at Mauao, spread around the base of the mountain under the skirts of the pohutukawa forest, with some burrows higher up to a maximum of c.75m above sea level. It is one of New Zealand’s most common seabirds, with vast colonies on Moutuhora (Whale Island) off Whakatane, and a large number on Motuotau (Rabbit Island) just offshore from Moturiki (Leisure Island).
There are no Grey-faced Petrel burrows being used currently on Moturiki, but a few burrows of similar size have been found.
The Ornithological Society of New Zealand (now Birds NZ) has collected data from Motuotau and Mauao in the past to see if the birds were maintaining their numbers.
It was proven that in fifty years time, without pest control, the numbers birds using the Mauao colony would be half the number they are now. In 200 years, there would be no birds. Current pest control methods are maintaining the numbers of birds.