Cape Verde Shearwater vs Black-vented Shearwater

Cape Verde Shearwater

Calonectris edwardsii

How to recognise a cape verde shearwater?

Cape Verde Shearwater Identification

1. General appearance - The Cape Verde Shearwater is a medium-sized seabird, characterized by its slender body, long wings, and moderate forked tails. It has a mix of dark brown and pale grey coloration on its upper parts, with a more uniform greyish-white underside. A subtle darker cap over its head may blend into the pale throat. The wings, long and nimble, enable agile flight patterns over the ocean. 2. Male vs female - There is little to no visible differentiation between the male and female Cape Verde Shearwaters. Both sexes share an identical plumage pattern and size range, making it challenging to distinguish between them by appearance alone. 3. Juvenile - Juvenile Cape Verde Shearwaters resemble adults in many ways but may have slightly duller plumage. Young birds often exhibit a smaller build compared to fully-grown adults, with softer feather textures that later mature into the sleek and streamlined profile of adult shearwaters.

Size

16.9 - 20.9 in/10.2 - 14.3 oz

Habitat

Primary habitat

The Cape Verde Shearwater primarily inhabits the coastal waters and islands of Cape Verde. It prefers temperate maritime climates, nesting on rocky cliffs and slopes near the ocean. These birds are pelagic and spend considerable time at sea, exploiting nutrient-rich waters for feeding.

Additional range

Outside nesting seasons, the shearwaters may venture into the open Atlantic Ocean, adapting to varying marine environments. They exhibit flexibility in habitat by occasionally foraging near different archipelagos, benefiting from seasonal oceanic shifts to expand their feeding grounds.

Range Map

What do cape verde shearwaters like to eat?

Natural diet

The Cape Verde Shearwater is primarily a marine bird, and its diet is composed of various marine organisms found in the ocean. These birds predominantly feed on small fish, such as sardines and anchovies, which they capture by diving into the water. They are also known to consume squid and crustaceans, often locating their prey near the sea surface. These shearwaters are opportunistic feeders and may follow other marine predators, like dolphins, to find food. Their feeding habits can vary with seasonal shifts in prey availability; during certain times of the year, they may focus more on squid if fish populations are low.

Bird feeders

Cape Verde Shearwaters are not typically attracted to bird feeders as they are ocean-dwelling birds that seek food primarily in marine environments. Unlike songbirds or other terrestrial avians, their feeding habits are not suited to consuming seeds, fruits, or suet often provided at bird feeders. Instead, their natural preference leans towards maritime life, where they can find the necessary nutrients and energy to sustain themselves. Residential areas are unlikely to see these birds at feeders, as they thrive on ocean currents and the bounty they provide.

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Black-vented Shearwater

Puffinus opisthomelas

How to recognise a black-vented shearwater?

General Appearance

The Black-vented Shearwater is a medium-sized seabird featuring a streamlined body adapted for dynamic soaring. Its upperparts are primarily dark brown to charcoal, complemented by paler underparts, showcasing a striking contrast. Characteristically, it has a distinctive black ventral area which extends down to its undertail coverts. The bird's wings are long and tapered with pale grayish-white shading underneath, a key field mark during flight. Its bill is short, light gray with a hook at the tip, and the legs and feet are pink, providing subtle hints of color against its darker plumage.

Male vs Female

The Black-vented Shearwater exhibits minimal sexual dimorphism, making it challenging to distinguish between males and females through visual observation alone. Both sexes share the same plumage coloration, size, and shape, and typically weigh about the same, a common trait among many shearwater species. Behavioral observations during mating seasons might offer some differentiation, yet visually, they are largely indistinguishable.

Juvenile

Juvenile Black-vented Shearwaters closely resemble adults but can be identified by their slightly duller and softer plumage, which aids in camouflaging them from predators during their early life stages. They lack the more defined contrast seen in adults, appearing more uniformly gray. As juveniles grow and undergo their first molt, their plumage becomes more defined and similar to that of mature adults. Recognizing young birds in the field requires a keen eye for these subtle shifts in coloration and texture.

Size

11.8 - 16.9 in/8.9 - 13.4 oz

Habitat

Primary habitat

The Black-vented Shearwater primarily inhabits the coastal regions of the Pacific Ocean, particularly around the Baja California Peninsula. They breed on offshore islands, favoring areas with sandy soils where they can dig burrows. The climate in these regions is typically arid to semi-arid, with warm temperatures and limited rainfall.

Additional range

Outside the breeding season, Black-vented Shearwaters can be found along the Californian coast up to central California. They demonstrate adaptability by inhabiting pelagic zones far from the shore, utilizing the open ocean for feeding and migration despite primarily being coastal birds.

Range Map

What do black-vented shearwaters like to eat?

Natural diet

The Black-vented Shearwater primarily feeds on fish and squid, diving from the surface to catch its prey. These birds are known for following fishing vessels to take advantage of discarded bycatch. They exhibit a varied and opportunistic diet, adjusting according to food availability in their environment. During breeding season, they may expand their diet to include krill and other small marine organisms to meet the increased energy demands.

Bird feeders

While Black-vented Shearwaters don't typically visit bird feeders due to their marine-dependent dietary habits, they can occasionally be drawn to areas where fishermen dispose of fish waste. They have evolved to thrive on oceanic food sources, and typical bird feeder offerings like seeds and suet are not appealing or suitable for them. However, if shore-based feeding is attempted, providing fish scraps or similar marine fare might momentarily catch their interest. Yet, it's essential to maintain their natural habits and not rely on human-provided food.

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Cape Verde Shearwater

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Black-vented Shearwater

Cape Verde Shearwater

Calonectris edwardsii

Cape Verde Shearwater Identification

1. General appearance - The Cape Verde Shearwater is a medium-sized seabird, characterized by its slender body, long wings, and moderate forked tails. It has a mix of dark brown and pale grey coloration on its upper parts, with a more uniform greyish-white underside. A subtle darker cap over its head may blend into the pale throat. The wings, long and nimble, enable agile flight patterns over the ocean. 2. Male vs female - There is little to no visible differentiation between the male and female Cape Verde Shearwaters. Both sexes share an identical plumage pattern and size range, making it challenging to distinguish between them by appearance alone. 3. Juvenile - Juvenile Cape Verde Shearwaters resemble adults in many ways but may have slightly duller plumage. Young birds often exhibit a smaller build compared to fully-grown adults, with softer feather textures that later mature into the sleek and streamlined profile of adult shearwaters.

Size

16.9 - 20.9 in/10.2 - 14.3 oz

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Black-vented Shearwater

Puffinus opisthomelas

General Appearance

The Black-vented Shearwater is a medium-sized seabird featuring a streamlined body adapted for dynamic soaring. Its upperparts are primarily dark brown to charcoal, complemented by paler underparts, showcasing a striking contrast. Characteristically, it has a distinctive black ventral area which extends down to its undertail coverts. The bird's wings are long and tapered with pale grayish-white shading underneath, a key field mark during flight. Its bill is short, light gray with a hook at the tip, and the legs and feet are pink, providing subtle hints of color against its darker plumage.

Male vs Female

The Black-vented Shearwater exhibits minimal sexual dimorphism, making it challenging to distinguish between males and females through visual observation alone. Both sexes share the same plumage coloration, size, and shape, and typically weigh about the same, a common trait among many shearwater species. Behavioral observations during mating seasons might offer some differentiation, yet visually, they are largely indistinguishable.

Juvenile

Juvenile Black-vented Shearwaters closely resemble adults but can be identified by their slightly duller and softer plumage, which aids in camouflaging them from predators during their early life stages. They lack the more defined contrast seen in adults, appearing more uniformly gray. As juveniles grow and undergo their first molt, their plumage becomes more defined and similar to that of mature adults. Recognizing young birds in the field requires a keen eye for these subtle shifts in coloration and texture.

Size

11.8 - 16.9 in/8.9 - 13.4 oz

There's more to learn about Black-vented Shearwater

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How to tell the Cape Verde Shearwater from the Black-vented Shearwater

Visual differences

The Cape Verde Shearwater is larger than the Black-vented Shearwater, measuring 17-21 inches in length, compared to the Black-vented's 12-17 inches. The Cape Verde has a sleeker, elongated build with contrasting lighter underparts and a pale face, while the Black-vented exhibits darker, more uniform gray plumage, especially noted in juveniles. The Cape Verde features a more pronounced, hooked beak, whereas the Black-vented's beak is shorter and more rounded. These differences in size, plumage contrast, and beak shape aid in distinguishing the two species.

Key differences and behavior

Cape Verde and Black-vented Shearwaters both exhibit remarkable oceanic adaptability but differ in several key behavioral aspects. Cape Verde Shearwaters are known for their eerie calls and loyalty to familiar nesting sites on Cape Verde's rocky coastlines, while Black-vented Shearwaters nest on isolated islands near Baja California, favoring sandy soils. Both species form monogamous bonds, yet Cape Verde Shearwaters rely more on vocal courtship, whereas Black-vented Shearwaters engage in social interactions and synchronized displays. Their diets overlap, focused on fish and squid, but Black-vented Shearwaters are more opportunistic, often following fishing vessels. Notably, Cape Verde Shearwaters are slightly larger, weighing up to 0.89 lbs (405g), compared to the maximum 0.84 lbs (380g) of Black-vented Shearwaters, offering a subtle field distinction.