The Buller's Shearwater only breeds on a few areas in the Poor Knights Islands of New Zealand, but are regular visitors during the summer and early fall off the west coast of North America. They are relatively common off the west coast of the U.S. in the late summer and early fall, and overall populations appear to be stable. However, due to the extremely restricted breeding range, there are conservation concerns about the Buller's Shearwater, as a single disturbance event on their nesting islands or the accidental introduction of predators such as rats could be devastating to the species as a whole.
Habitat
Nests on a few islands near New Zealand, with suitable soil for digging burrows, or with rocky areas with adequate protected sites for nest building. Outside of the breeding season, they are typically found near upwelling currents, far from shore.
Diet
Feeds mostly on fish, squid, and small crustaceans.
Behavior
May use a variety of foraging techniques to capture food at or near the surface of the ocean. This includes short plunge dives, swimming on the surface and plucking food items, or dipping down while in flight and skimming food items from near the surface.
Nesting
The nest of a Buller's Shearwater is in a burrow, in a crevice in a rocky area, or in another similar protected area. The nest itself consists of a lining of pebbles, twigs, and other vegetation. The female lays a single egg, and both the male and female help to incubate it. Upon hatching, both parents help to feed the young, regurgitating food that they have captured.
Song
Usually silent
Migration
Buller's Shearwaters only breed on the Poor Knights Islands in New Zealand. Outside of the breeding season, the move north in the Pacific, and can be common in parts of the Pacific in summer and early fall.
Interactive eBird Map
Click to access an interactive eBird map of Buller's Shearwater sightings
Similar Species
In range, most likely to be confused with the Pink-footed Shearwater. Other smaller shearwater species in the Pacific off North America have white underparts and darker upperparts, but the Buller's and the Pink-footed are the only two large shearwater species with such a pattern. If seen well, the "crisp" plumage of the Buller's, with sharper borders between light and dark, is obvious compared to the "muddier" Pink-footed Shearwater. Also similar to the Wedge-tailed Shearwater, a extremely rare vagrant in North America.
Conservation Status
Global populations of Buller's Shearwaters are still thought to number over 1 million birds. However, because of their extremely restricted breeding range, they are considered at risk from introduced predators or other disturbances on their breeding islands. The IUCN lists the Buller's Shearwater as a "Vulnerable" species .
Further Information
Photo Information
Photo taken by Greg Schechter - September 24th, 2011 - Off the coast of Pacific Grove, California - Photo licensed under Creative Commons Attribution 2.0 Generic license .
