BULLER'S SHEARWATER


Buller's Shearwater - Field Marks

Monterey Bay, California, is a good place to look for this pelagic species. Take a boat trip into the bay to enjoy spectacular birding and an opportunity to see mammals such as the sea otter.

Buller's Shearwater
Puffinus bulleri
Formerly: New Zealand Shearwater

A cleanly patterned seabird, nesting only near New Zealand but visiting waters off the west coast of North America in fall. Buller's seems more buoyant and graceful in flight than most shearwaters, with more gliding and less flapping. It often arcs up high on one wingtip and then the other, and small flocks may turn and glide over the waves in unison.

Field Marks
A rather uncommon white-bellied shearwater; separated from the two other West Coast white-bellied species by a broad M or W formed by the contrasting pattern on back and wings. Tail wedge-shaped. Feet pale, but variable.

Size
16 1/2" (42 cm)

Range
Breeds northern New Zealand. Fall visitor offshore along our Pacific Coast, mostly from central California north to Washington, rare north to Alaska.

Buller's Shearwater - Range Map

Migration
Breeding adults move north in May, common in parts of North Pacific in summer, returning to New Zealand by September. Seen off our Pacific Coast mainly June to November, most common September-October; evidently these are mostly non-breeders and immatures.

Habitat
Open ocean. Tends to concentrate at areas of strong upwelling, or where warm and cool water currents meet, bringing food to the surface. Rarely comes close to shore. Nests on islands with soil suitable for burrows or with crevices among rocky cliffs.

Feeding
Diet: Crustaceans, fish, squid. Diet not well known. Near breeding grounds may feed mostly on euphausiid shrimp and other crustaceans. Off California, may eat mostly small fish and squid.

Behavior: Food is taken at or just below surface of water. Forages by dipping to surface in flight, plunging into water from a few feet above surface, swimming with head submerged, sometimes upending with head down and tail up. Rarely dives underwater. May feed at night.

Nesting
Breeds on Poor Knights Islands off North Island, New Zealand. Adults arrive there in September, most eggs laid in late November, young depart in May. Breeds in dense colonies. Adults noisy around colonies at night, may climb up into trees to take flight more easily.

Nest: Site is in burrow under tree roots or rocks, or in cave or rock crevice. Both sexes help dig burrow. Nest chamber is lined with leaves, twigs, pebbles. Where birds nest in Maori burial caves, may use human bones as nest material.

Eggs: 1 per season. White. Incubation is by both sexes, roughly 51 days.

Young: Both parents feed young, by regurgitation. Period from hatching to departure from nest probably about 100 days, but not well known.

Conservation
On some islands, where colonies were nearly wiped out by feral pigs, shearwaters recolonized after pigs were eradicated in 1936. Total population estimated at more than 2 million.

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