Flesh-footed Shearwater vs Buller's Shearwater

Flesh-footed Shearwater

Ardenna carneipes

How to recognise a flesh-footed shearwater?

General appearance

The Flesh-footed Shearwater is recognized by its uniform dark plumage, with feathers ranging from warm brown to almost black. Its flesh-colored legs and feet are striking against the dark body. The bill is pale, broad, and hooked at the tip, which helps distinguish it from similar species. The sheer size of this bird can also be notable, as it measures approximately 40-45 centimeters in length, with a wingspan of around 99-107 centimeters. The wings are long and slender, enabling it to glide effortlessly over the ocean.

Male vs female

There is very minimal sexual dimorphism in the Flesh-footed Shearwater, making it challenging to differentiate males from females based solely on appearance. Both sexes display the same dark plumage and flesh-colored feet. Their sizes are also comparable, with no significant variance in weight or wingspan that would aid identification.

Juvenile

Juvenile Flesh-footed Shearwaters closely resemble adult birds in coloration and size. However, juveniles can be identified by their slightly less worn feather quality, often appearing fresher and less glossy than those of adults. They might also venture closer to breeding colonies as they explore their surroundings, offering a clue to their age.

Size

15.7 - 18.9 in/22.9 - 28.6 oz

Habitat

Primary Habitat

The Flesh-footed Shearwater primarily inhabits the open oceans and coastal waters of the southern hemisphere. Its typical range includes the warm temperate and subtropical regions of the Indian and Pacific Oceans. They regularly breed on islands off Australia and New Zealand, favoring burrows on sloped terrains with vegetation that offer shelter.

Additional Range

Beyond their main habitat, these birds might adapt to cooler waters, venturing into more northern latitudes during non-breeding seasons. Occasionally, they are observed in unexpected coastal areas, attracted by food availability, particularly during migratory journeys.

Range Map

What do flesh-footed shearwaters like to eat?

Natural diet

The Flesh-footed Shearwater, which inhabits open ocean areas, predominantly feeds on marine prey. Its diet mainly consists of fish, squid, and crustaceans, which it catches by surface seizing during gliding flights. The bird's feeding behavior shows some seasonal variation, with a higher intake of squid during breeding seasons when they are most abundant. Due to its pelagic lifestyle, the Flesh-footed Shearwater relies heavily on the availability of shoaling fish, benefiting from the natural processes and upwellings that bring prey to the ocean surface.

Bird feeders

Flesh-footed Shearwaters do not visit land-based bird feeders or consume typical feeder offerings such as seeds or suet. As a seabird, it is specialized in marine environments and does not adapt well to terrestrial feeding scenarios. If individuals are found near coastal regions or islands, it is usually in search of natural marine food sources or during breeding seasons, rather than seeking food from human-provided feeders. Bird feeding recommendations for shore or sea bird conservation should emphasize the preservation of their natural habitats and food sources rather than supplementing with alternatives suited to land birds.

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Buller's Shearwater

Ardenna bulleri

How to recognise a 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.

Size

18.1 in/15.0 - 17.5 oz

Habitat

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.

Range Map

What do buller's shearwaters like to eat?

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.

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Flesh-footed Shearwater

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Buller's Shearwater

Flesh-footed Shearwater

Ardenna carneipes

General appearance

The Flesh-footed Shearwater is recognized by its uniform dark plumage, with feathers ranging from warm brown to almost black. Its flesh-colored legs and feet are striking against the dark body. The bill is pale, broad, and hooked at the tip, which helps distinguish it from similar species. The sheer size of this bird can also be notable, as it measures approximately 40-45 centimeters in length, with a wingspan of around 99-107 centimeters. The wings are long and slender, enabling it to glide effortlessly over the ocean.

Male vs female

There is very minimal sexual dimorphism in the Flesh-footed Shearwater, making it challenging to differentiate males from females based solely on appearance. Both sexes display the same dark plumage and flesh-colored feet. Their sizes are also comparable, with no significant variance in weight or wingspan that would aid identification.

Juvenile

Juvenile Flesh-footed Shearwaters closely resemble adult birds in coloration and size. However, juveniles can be identified by their slightly less worn feather quality, often appearing fresher and less glossy than those of adults. They might also venture closer to breeding colonies as they explore their surroundings, offering a clue to their age.

Size

15.7 - 18.9 in/22.9 - 28.6 oz

There's more to learn about Flesh-footed Shearwater

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Buller's Shearwater

Ardenna bulleri

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.

Size

18.1 in/15.0 - 17.5 oz

There's more to learn about Buller's Shearwater

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How to tell the Flesh-footed Shearwater from the Buller's Shearwater

Visual differences

The Flesh-footed Shearwater and Buller's Shearwater differ visually in several ways. Flesh-footed Shearwaters are larger, measuring 16-19 inches long, with uniform dark plumage, pale hooked bills, and flesh-colored legs. In contrast, Buller's Shearwaters are approximately 18 inches long, featuring distinctively patterned gray and white plumage, a slender, dark-tipped bill, and darker feet. The wingspan of Flesh-footed Shearwaters is broader at 39-42 inches, compared to Buller's at around 35-39 inches. These differences aid in identifying these pelagic birds at sea.

Key differences and behavior

Flesh-footed Shearwaters (Ardenna carneipes) and Buller’s Shearwaters (Ardenna bulleri) both exhibit oceanic lifestyles but differ significantly in their behaviors and preferences. Both species engage in extensive migrations, yet Flesh-footed Shearwaters travel between the Pacific and Indian Oceans, while Buller's Shearwaters migrate from New Zealand to the North Pacific. Flesh-footed Shearwaters uniquely use plunge-diving and sometimes kleptoparasitism for feeding, preferring fish, squid, and crustaceans. In contrast, Buller’s Shearwaters skim the surface for squid and small fish and may follow fishing boats for leftovers. While both species nest on isolated islands, Flesh-footed Shearwaters utilize vegetation-rich burrows more commonly, whereas Buller’s prefer elevated ground. Both birds display strong courtship and pair bonding, laying a single egg each season, but they differ in habitat adaptability and feeding choices.