Puffinus gavia (J.R.Forster, 1844)

Species Common Name and Overall Appearance

Puffinus gavia, commonly called the fluttering shearwater, is a small to medium-sized shearwater with a dark brown and white body.

Upperparts Coloration

Its upperparts, including the neck, wings, and tail, are uniformly dark brown. The face and upper neck are grey-brown, fading gradually to white below the eye.

Underbody Coloration

The underbody, from the chin to undertail coverts, is white, save for a dark thigh patch visible when the bird is in flight.

Underwing Coloration

The underwing is usually white, while the axillary area is covered in grey-brown feathers.

Legs and Feet Characteristics

Legs and feet are pinkish-brown with dark webbing, and the feet extend past the tail during flight.

Bill Characteristics

The bill is long, thin, and dark.

Tail Characteristics

The short, fan-shaped tail shows a mix of dark brown and white in flight.

Moulting Schedule and Appearance

Moulting begins in late January, and dark upper surfaces quickly fade to mid-brown. Birds nearing moult, from February to April, are pale rusty brown and appear ragged.

Vocalization

The species’ call is an unusual, disjointed ka-hek-ka-hek-ka-hek, typically given in flight.

Flight Pattern

Its flight is low and fast, consisting of rapid bursts of wingbeats alternating with gliding.

Average Body Mass

Average body mass is 302 g (10.7 oz) for females and 243 g (8.6 oz) for males.

Egg Characteristics

Eggs are pure white and oval-shaped.

Juvenile Plumage

Juveniles already match the adult coloration when in the nest, but have paler edges on their wing coverts.

Nestling Plumage

Nestlings have thick, soft slate-coloured feathers on their upperparts and white down on their underparts.

Endemic Range

The fluttering shearwater is endemic to New Zealand.

Breeding Season Timing

It breeds there during the warmer months from September to February.

Non-breeding Distribution

During the non-breeding season between March and August, large numbers of the species are observed along eastern and south-eastern Australia, though most individuals remain near their New Zealand breeding colonies.

Migration Hypothesis

It is suspected that only juveniles migrate while adults stay in New Zealand’s productive waters, but this has not been confirmed.

New Zealand Breeding Range

In New Zealand, fluttering shearwaters breed on coastal islands across the country.

North Island Breeding Locations

Large breeding populations are found on north-eastern North Island islands including the Aldermen Islands, Moturoa Island, Bream Islands, north-west Chicken Islands, Mercury Islands, and Motuharakeke Island in the Cavalli Islands.

South Island Breeding Locations

They also breed on islands throughout the Marlborough Sounds and Cook Strait region of the South Island.

Breeding Island Proximity to Mainland

Most breeding islands are offshore and located within 40 km of the New Zealand mainland.

Occupied Habitat Types

Fluttering shearwaters occupy both marine and terrestrial habitats, including coastal marine areas, scrubland, and forest.

Marine Habitat Parameters

They are most often found in subtropical waters at around 24 °C with intermediate to high salinity of approximately 35%.

Inshore Habitat Usage

They are common in accessible inshore areas such as harbours, inlets, bays, and straits.

Breeding Site Characteristics

For breeding, they typically choose stony, scrub-covered slopes near hill peaks, as well as rock cracks and holes located far from the water, which gives them clear space for takeoff.