Hawaiian Petrel vs Cook's Petrel

Hawaiian Petrel

Pterodroma sandwichensis

How to recognise a hawaiian petrel?

General Appearance

The Hawaiian Petrel is a striking seabird known for its dark gray or almost black upperparts and contrasting white underparts. Its wings are long and pointed, aiding in its efficient flight over the ocean. Notable features include a white forehead and face, with a distinct dark gray stripe running through each eye. The bill is slender and black, curved at the tip. Its tail is relatively short and fan-shaped, often visible against the sky as the bird glides high above the waves.

Male vs Female

There are no significant differences in the appearance of male and female Hawaiian Petrels. Both sexes possess similar plumage and physical traits, making gender identification in the field nearly impossible without closer inspection or genetic analysis. This lack of sexual dimorphism suggests that both males and females share similar roles in nesting and caring for young.

Juvenile

Juvenile Hawaiian Petrels resemble adults but with some subtle features that differentiate them. Young birds often have slightly duller plumage and may exhibit a less refined bill structure. The gray on their upperparts lacks the same depth of color seen in mature birds. As they age, their feathers will achieve the darker shades and distinctive markings that characterize adult petrels. In their first year, juveniles undergo molt as they transition to mature plumage, completing their transformation by the end of their first year.

Size

15.7 - 18.1 in/13.1 - 21.2 oz

Habitat

Hawaiian Petrel Habitat

Primary habitat: The Hawaiian Petrel primarily inhabits the mountainous regions on the Hawaiian Islands, such as Maui and the Big Island. These seabirds prefer nesting in burrows on steep slopes, within native forests that offer protective cover from predators. They range primarily across open ocean waters, feeding during their vast marine journeys. Additional range: While primarily marine, Hawaiian Petrels have also been spotted in lowland coastal areas when resting during migrations. Their adaptability allows them to feed over deep ocean waters and occasionally nest on isolated inshore and offshore islands.

Range Map

What do hawaiian petrels like to eat?

Natural diet

The Hawaiian Petrel predominantly feeds on a diet consisting of oceanic prey. These seabirds primarily consume squid and small fish, which provide the necessary nutrients for their energetic lifestyle. During the nesting season, they embark on extensive foraging trips, traveling vast distances to hunt for food. They often capture their prey at night, utilizing a keen sense of smell and sight. While their diet does fluctuate slightly during breeding, squid remains an essential component throughout the year. During warmer months, when squid populations are abundant, their consumption increases.

Bird feeders

The Hawaiian Petrel is not known to visit bird feeders, as its feeding habits are closely tied to marine environments. These seabirds are not attracted to the typical offerings found in backyard settings, such as seeds or suet. Their diet relies heavily on open ocean resources, making them unlikely to benefit from typical bird feeder provisions. As such, there are no specific feeder recommendations or preferences for the Hawaiian Petrel, given its specialized foraging behavior and dietary requirements.

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Cook's Petrel

Pterodroma cookii

How to recognise a cook's petrel?

General appearance

Cook's Petrel is a medium-sized seabird featuring a streamlined body and long, slender wings. The plumage predominantly consists of striking blue-gray tones on the back and upper wings while the underparts are white, contributing to its distinct appearance. The bird's face exhibits a sharp contrast with a dark brown mask extending from the eyes to the beak. Its tail is short and wedge-shaped, maintaining a similar blue-gray coloring. The Petrel’s slender, black bill is perfectly adapted for its dietary habits in the wild.

Male vs female

Cook's Petrel shows minimal sexual dimorphism, meaning that males and females look strikingly similar. Both sexes boast the same color patterns and body size, making it difficult to distinguish between them based solely on external characteristics.

Juvenile

Juveniles closely resemble adults but might possess slightly duller plumage and less defined facial markings. Their dark face mask may not be as prominent, and the contrast between the blue-gray upper parts and white underparts can appear less distinct. As they mature, the plumage becomes more vivid, attaining the characteristic features of adult Cook's Petrel. Juvenile birds are often less experienced fliers but gradually gain proficiency as they age.

Size

10.2 - 11.8 in/3.0 - 7.8 oz

Habitat

Cook's Petrel Habitat Description

Primary habitat - Cook's Petrel predominantly roams the open ocean, primarily inhabiting subtropical and temperate marine zones. They breed exclusively on few island sites in New Zealand, notably Little Barrier Island, breeding in burrows on forested ridges. This species favors the vast expanses of the South Pacific Ocean during non-breeding seasons, where they find ample food supply and minimal land-based threats. Additional range - Outside their primary range, Cook's Petrel has occasionally been observed in diverse climatic conditions such as the coastal waters of South America. These sightings suggest some adaptability to varying environments, albeit infrequently.

Range Map

What do cook's petrels like to eat?

Natural diet

Cook's Petrel, primarily a marine bird, has a diet that revolves around the rich resources of the ocean. These birds feed mostly on small fish, cephalopods like squid, and various crustaceans found in offshore waters. Their dietary patterns may shift slightly with seasonal changes, as they tend to follow the distribution of prey that is most readily available. These petrels are foraging experts, using their sharp beaks to catch agile fish and their keen eyesight to spot prey in surface waters.

Bird feeders

Given their nature as seabirds, Cook's Petrels do not typically visit bird feeders. They thrive in open ocean environments and are adept at capturing their preferred marine food sources, making traditional feeder foods like seeds, suet, and fruits largely unsuitable. Birdwatchers may admire their flying prowess over oceans but won't typically encounter them at feeders in gardens or parks. To attract more common feeder-friendly birds, offering foods like black oil sunflower seeds, mealworms, or nectar may yield more success.

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Hawaiian Petrel

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Cook's Petrel

Hawaiian Petrel

Pterodroma sandwichensis

General Appearance

The Hawaiian Petrel is a striking seabird known for its dark gray or almost black upperparts and contrasting white underparts. Its wings are long and pointed, aiding in its efficient flight over the ocean. Notable features include a white forehead and face, with a distinct dark gray stripe running through each eye. The bill is slender and black, curved at the tip. Its tail is relatively short and fan-shaped, often visible against the sky as the bird glides high above the waves.

Male vs Female

There are no significant differences in the appearance of male and female Hawaiian Petrels. Both sexes possess similar plumage and physical traits, making gender identification in the field nearly impossible without closer inspection or genetic analysis. This lack of sexual dimorphism suggests that both males and females share similar roles in nesting and caring for young.

Juvenile

Juvenile Hawaiian Petrels resemble adults but with some subtle features that differentiate them. Young birds often have slightly duller plumage and may exhibit a less refined bill structure. The gray on their upperparts lacks the same depth of color seen in mature birds. As they age, their feathers will achieve the darker shades and distinctive markings that characterize adult petrels. In their first year, juveniles undergo molt as they transition to mature plumage, completing their transformation by the end of their first year.

Size

15.7 - 18.1 in/13.1 - 21.2 oz

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Cook's Petrel

Pterodroma cookii

General appearance

Cook's Petrel is a medium-sized seabird featuring a streamlined body and long, slender wings. The plumage predominantly consists of striking blue-gray tones on the back and upper wings while the underparts are white, contributing to its distinct appearance. The bird's face exhibits a sharp contrast with a dark brown mask extending from the eyes to the beak. Its tail is short and wedge-shaped, maintaining a similar blue-gray coloring. The Petrel’s slender, black bill is perfectly adapted for its dietary habits in the wild.

Male vs female

Cook's Petrel shows minimal sexual dimorphism, meaning that males and females look strikingly similar. Both sexes boast the same color patterns and body size, making it difficult to distinguish between them based solely on external characteristics.

Juvenile

Juveniles closely resemble adults but might possess slightly duller plumage and less defined facial markings. Their dark face mask may not be as prominent, and the contrast between the blue-gray upper parts and white underparts can appear less distinct. As they mature, the plumage becomes more vivid, attaining the characteristic features of adult Cook's Petrel. Juvenile birds are often less experienced fliers but gradually gain proficiency as they age.

Size

10.2 - 11.8 in/3.0 - 7.8 oz

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How to tell the Hawaiian Petrel from the Cook's Petrel

Visual differences

Hawaiian Petrel (Pterodroma sandwichensis) is larger, weighing 13-21 oz (370-600g) and measuring 16-18 in (40-46cm) in length, compared to Cook's Petrel (Pterodroma cookii), which weighs 3-8 oz (86-220g) and measures 10-12 in (26-30cm). Hawaiian Petrel's plumage is darker with deep gray upperparts, while Cook's Petrel features blue-gray upperparts with a distinctive white underside and dark mask. Both have slender bills, but Cook's Petrel's bill is thinner and black. Hawaiian Petrel's tail is more rounded, whereas Cook's Petrel's is short and wedge-shaped.

Key differences and behavior

Hawaiian Petrels and Cook's Petrels exhibit distinct behaviors and habitats. Hawaiian Petrels primarily inhabit the Hawaiian Islands' mountainous regions, nesting in isolated burrows on volcanic slopes. They are nocturnal hunters, relying heavily on squid and fish, and are known for their intricate courtship displays involving synchronized flights. In contrast, Cook's Petrels breed on New Zealand's islands, frequenting open ocean waters for feeding, predominantly on fish and cephalopods. They are renowned for incredible long-distance migrations and synchronized aerial courtship, like Hawaiian Petrels. Both species lay a single egg per season and are monogamous, but Cook's Petrels have a shorter incubation period (50 days). Hawaiian Petrels weigh 370-600g with a length of 16-18in, while Cook's Petrels are lighter and shorter at 86-220g and 10-12in, respectively. Hawaiian Petrels specialize in star navigation, while Cook's Petrels handle extensive migrations without relying on stars.