Grey-faced Petrel / Ōi

The grey-faced petrel, also known as the Northern muttonbird, is a species of petrel endemic to the North Island of New Zealand. It is rarely seen in the sheltered waters of the Whangamatā Harbour but is often observed soaring fast and gracefully over the waves in search of their food sources in the deeper seawaters around the Coromandel peninsular. They generally feed alone but sometimes in small flocks, when seeking their favoured food squid.

Grey-faced Petrel. Photo credit Corinne Bowie.

Most of their feeding activity is at night when many of the squid species they target are more active near the sea surface. Studies have shown the majority of their food foraging is undertaken out over the continental shelf and beyond and is obtained mostly in the top 5m. However, they are capable of diving down to a depth of 23m.

Like many of the seabirds known generally as petrels, grey-faced petrel nest mainly in burrows excavated amongst tree roots on pest free islands in the upper North Island. A few small mainland island colonies still survive on some headlands and peninsulas around coasts of this area. The largest colonies occur on the Manawatāwhi (Three Kings), Hen and Chickens, Mokohinau, Mercury and Alderman Island groups, and also on Cuvier, Moutohorā (Whale), Whakaari (White) and East Islands. Small numbers are known to nest here on the Whangamatā Islands of Whenuakura (Donut), Hauturu (Clarke) and Maukaha. Their total population is thought to be in the order of 200,000 to 300,000 pairs. Their Conservation status is Partially Protected and a small number of chicks are legally harvested by Maori each year from nesting colonies on privately owned islands.

The grey-faced petrel is a largish petrel, 41cm long and weighing around 550gm, with plumage uniformly dark black-brown in colour. As its name suggests the feathering around its bill and throat is grey. Their eyes, legs and stout beak are black, with the beak boasting a large sharp hook which is used when capturing, holding and devouring their favoured prey.

This species has a particularly long breeding season, starting with burrow nest construction and mating courtship activity in March. Egg-laying commences in late June and July with just the one egg laid per pair. Incubation is carried out by the female for the first 4-16 days, followed by successive shifts of varying lengths by both parents. Eggs hatch after about 55 days incubation over the period mid-August to mid-September.

The emergent chicks are guarded for the first 2-3 days and then fed about every 4 days by both parents until fledging. They depart their underground homes from around early December to late January when about 118 days old. These young won’t commence breeding themselves until they are 7-10 years old. The oldest known bird recorded lived for over 40 years.

Unfortunately small numbers of young birds, new to flying, are driven ashore here during severe on-shore storm conditions. They are also attracted to the town's lights during such conditions and often in a disorientated and weakened state crash into buildings and other structures injuring themselves in the process. People finding such injured or weakened birds are urged to report their location to the Department of Conservation using the 24/7 emergency hotline 0800 DOC HOT (0800 362 468), or capture and transport them to the local Veterinary Clinic.

— John Adams, Whangamatā Harbour Care