Cape Verde Shearwater or Buller's Shearwater?

Buller's Shearwater Identification Guide

The Buller's Shearwater is a striking medium-sized seabird identified by its sleek, aerodynamic body and graceful flight patterns. It possesses a striking appearance with dark gray upper parts contrasted by a pure white underbelly. The upper wings and back display a mix of gray and white patterns, which form a distinct 'M' shape when seen from above. The bird's tail is wedge-shaped, and its long, slender wings are adapted for gliding over the ocean. Males and females of the Buller's Shearwater are almost indistinguishable in appearance, exhibiting similar size and coloration. Both sexes share the same flattened bill and webbed feet, which are adaptations for their marine lifestyle. There is no significant sexual dimorphism, so distinguishing between them in the field can be challenging. Juvenile Buller's Shearwaters resemble adults but with subtle differences. Young birds often have slightly duller plumage and less distinct patterns on their upper parts. The 'M' pattern on the back may appear less prominent. Over time, as they mature and go through molt cycles, they attain the sharper contrast and clearer markings that characterize mature adults.

Primary habitat

Buller's Shearwater typically inhabits the open waters of the Pacific Ocean, primarily around New Zealand. They are often seen in areas where the continental shelf meets deeper waters, utilizing ocean currents to forage for squid and small fish. These birds prefer temperate climates with access to plentiful marine resources.

Additional range

In addition to their primary habitat, Buller's Shearwaters have been observed extending their range to the northern Pacific during their non-breeding season. They have displayed adaptability by venturing into subtropical and cooler waters along the coasts, occasionally seen as far as California and Japan.

Natural diet

The Buller's Shearwater primarily feeds on small fish and zooplankton found within pelagic marine environments. Their diet mainly consists of small schooling fish such as anchovies and sardines. They are also known to consume squid and krill, diving under water to catch their prey or sometimes seizing it while flying close to the surface. These birds often follow large marine predators or fishing boats, taking advantage of leftovers or the increased availability of prey items. Seasonal variations occur, and during certain months they may shift their diet focus based on the abundance of different prey species.

Bird feeders

Buller's Shearwaters are unlikely to visit terrestrial bird feeders as they are strictly oceanic birds. In typical garden settings where bird feeders are placed, one would not expect to attract a Buller's Shearwater. These birds do not consume seeds, suet, or fruit, as their diet is entirely based on marine sources. Observers interested in Buller's Shearwaters should look to see these birds in their natural habitat, the open sea, rather than trying to feed them in other settings.