Black Storm-Petrel vs Ashy Storm-Petrel

Black Storm-Petrel

Hydrobates melania

How to recognise a black storm-petrel?

Characteristics of Black Storm-Petrel

General appearance: The Black Storm-Petrel is a small seabird that exhibits predominantly sooty black plumage. Its feathers have a slightly glossy appearance, particularly noticeable in good lighting. This bird features a distinctly long, forked tail and long, slender wings, which help it navigate agilely over the ocean surface. The feet are notably dark, contributing to its overall black appearance, with pale webbing sometimes visible in flight. Male vs female: There is minimal sexual dimorphism in Black Storm-Petrels, meaning males and females appear almost identical to the untrained observer. Both sexes share the same sooty black colorations, long wings, and tail structure. As such, visual identification based on sex is typically not possible. Juvenile: The juvenile Black Storm-Petrel closely resembles the adult in terms of plumage and physical structure. However, juveniles may have slightly duller feathers and a less glossy sheen compared to mature birds. Their rectrices may also be shorter and less sharply forked, which may aid in differentiation from adults upon close inspection. Over time, as these juveniles mature, they adopt the full characteristic features of their adult counterparts.

Size

8.7 - 9.8 in/1.2 - 2.1 oz

Habitat

Primary habitat

The Black Storm-Petrel predominantly inhabits the offshore waters of the tropical and subtropical eastern Pacific Ocean. It thrives in the warm maritime climates spanning from California, along the Baja California Peninsula, and down to the Galápagos Islands. This species is typically found in pelagic zones, favoring open sea areas, and is rarely seen close to land.

Additional range

While mostly observed far from shore, the Black Storm-Petrel occasionally ventures nearer to coastal areas, especially during breeding seasons. They have the adaptability to withstand brief encounters with colder waters during long migrations or when following food sources, exhibiting resilient behavior in varied sea conditions.

Range Map

What do black storm-petrels like to eat?

Natural Diet

The Black Storm-Petrel, known for its distinctive dark plumage and erratic flight, predominantly feeds on oceanic-based natural food sources. This bird's diet mainly consists of small fish, squid, and various types of zooplankton, which it skillfully catches from the ocean surface. These seabirds often attend to "feeding fronts" where nutrient-rich waters attract ample prey. Seasonal variations can influence prey availability, with squid and small fish being more abundant during certain times of the year, such as in spring and summer when upwelling is more frequent. The petrels are adept at capitalizing on these fluctuations to sustain themselves.

Bird Feeders

While the Black Storm-Petrel's natural diet is heavily reliant on marine resources, there is limited interaction with traditional bird feeders, which usually cater to terrestrial and urban birds. Thus, it is unlikely for these seabirds to be seen at bird feeders on land, as they are highly adapted to extract their nutritional needs from the ocean. Bird feeding setups offering seed mixes, suet, or fruits do not typically attract storm-petrels, as these do not align with their natural feeding habits. Observing Black Storm-Petrels is best done along coastlines or aboard oceanic vessels, where their agile, sea-level foraging behavior can be witnessed firsthand.

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Ashy Storm-Petrel

Hydrobates homochroa

How to recognise an ashy storm-petrel?

Ashy Storm-Petrel Recognition Guide

General appearance: The Ashy Storm-Petrel is a small, slate-gray seabird notable for its uniformly ashy coloration without any striking patterns or contrasts. This bird typically measures about 18 to 20 centimeters in length with long, slender wings spanning approximately 43 to 47 centimeters. Its plumage has a soft, sooty color throughout, mirrored by dark brownish hue in its long, slightly forked tail. The bird's head, back, wings, and upper parts are varying shades of ashy gray, lending it camouflage against the ocean's murky horizons. Male vs female: Both the male and female Ashy Storm-Petrels showcase similar morphologies and plumage characteristics. There are no conspicuous differences, and thus, distinguishing the sexes based on appearance alone can be challenging. Both sexes share identical coloration and size, making external identification in the field infeasible without behavioral context or genetic analysis. Juvenile: Juvenile Ashy Storm-Petrels bear a close resemblance to adult birds with only subtle differences in appearance. They generally display slightly paler or duller plumage and may lack the full depth of coloration seen in mature birds. As juveniles age, they gradually acquire the adult's consistent ashy gray tone, completing the transition in several months as they mature in the marine environment.

Size

7.1 - 8.3 in/1.2 - 1.9 oz

Habitat

Primary Habitat

The Ashy Storm-Petrel primarily inhabits the coastal regions of the eastern North Pacific. This small seabird is most commonly found around the Channel Islands of California, preferring the cool, misty environments of rocky ocean islands. Its typical range extends from Northern California to Baja California, Mexico.

Additional Range

Beyond its preferred maritime climate, the Ashy Storm-Petrel has been observed straying into unexpected environments, such as offshore deep waters. During migration or dispersal, they may sporadically appear further inland. However, they remain largely dependent on island or coastal habitats for breeding and roosting.

Range Map

What do ashy storm-petrels like to eat?

Natural Diet

The Ashy Storm-Petrel primarily feeds at sea, where it forages for small fish, squid, and planktonic crustaceans. These birds often capture their prey by skimming near the water's surface, expertly dipping down to snatch meal items with their beaks. They occasionally follow ships to take advantage of fish scraps and other organic matter churned up in the water. There is little variation in their diet by season, as their foraging areas typically remain consistent year-round.

Bird Feeders

Bird feeders do not significantly supplement the diet of the Ashy Storm-Petrel, as its feeding habits are primarily geared towards marine environments. They rarely visit inland feeders, largely because they do not usually inhabit areas where feeders are prevalent. However, should an Ashy Storm-Petrel wander close to coastal feeders, it might show some curiosity towards fish-based suet or other seafood baits. Nevertheless, such occurrences are rare, and they are generally not observed feeding at human-provided feeder sources.

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Black Storm-Petrel

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Ashy Storm-Petrel

Black Storm-Petrel

Hydrobates melania

Characteristics of Black Storm-Petrel

General appearance: The Black Storm-Petrel is a small seabird that exhibits predominantly sooty black plumage. Its feathers have a slightly glossy appearance, particularly noticeable in good lighting. This bird features a distinctly long, forked tail and long, slender wings, which help it navigate agilely over the ocean surface. The feet are notably dark, contributing to its overall black appearance, with pale webbing sometimes visible in flight. Male vs female: There is minimal sexual dimorphism in Black Storm-Petrels, meaning males and females appear almost identical to the untrained observer. Both sexes share the same sooty black colorations, long wings, and tail structure. As such, visual identification based on sex is typically not possible. Juvenile: The juvenile Black Storm-Petrel closely resembles the adult in terms of plumage and physical structure. However, juveniles may have slightly duller feathers and a less glossy sheen compared to mature birds. Their rectrices may also be shorter and less sharply forked, which may aid in differentiation from adults upon close inspection. Over time, as these juveniles mature, they adopt the full characteristic features of their adult counterparts.

Size

8.7 - 9.8 in/1.2 - 2.1 oz

There's more to learn about Black Storm-Petrel

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Ashy Storm-Petrel

Hydrobates homochroa

Ashy Storm-Petrel Recognition Guide

General appearance: The Ashy Storm-Petrel is a small, slate-gray seabird notable for its uniformly ashy coloration without any striking patterns or contrasts. This bird typically measures about 18 to 20 centimeters in length with long, slender wings spanning approximately 43 to 47 centimeters. Its plumage has a soft, sooty color throughout, mirrored by dark brownish hue in its long, slightly forked tail. The bird's head, back, wings, and upper parts are varying shades of ashy gray, lending it camouflage against the ocean's murky horizons. Male vs female: Both the male and female Ashy Storm-Petrels showcase similar morphologies and plumage characteristics. There are no conspicuous differences, and thus, distinguishing the sexes based on appearance alone can be challenging. Both sexes share identical coloration and size, making external identification in the field infeasible without behavioral context or genetic analysis. Juvenile: Juvenile Ashy Storm-Petrels bear a close resemblance to adult birds with only subtle differences in appearance. They generally display slightly paler or duller plumage and may lack the full depth of coloration seen in mature birds. As juveniles age, they gradually acquire the adult's consistent ashy gray tone, completing the transition in several months as they mature in the marine environment.

Size

7.1 - 8.3 in/1.2 - 1.9 oz

There's more to learn about Ashy Storm-Petrel

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How to tell the Black Storm-Petrel from the Ashy Storm-Petrel

Visual differences

The Black Storm-Petrel (8.7-9.8 inches, 1.2-2.1 ounces) is larger and darker than the Ashy Storm-Petrel (7.1-8.3 inches, 1.2-1.9 ounces), which has smoky gray plumage. Black Storm-Petrels have a more uniform dark color, while Ashy Storm-Petrels exhibit a lighter, ash-colored hue blending into misty environments. Both have slender beaks, but the Ashy Storm-Petrel's gray plumage provides better camouflage in their foggy habitats, making it harder to spot compared to the typically open sea-favoring Black Storm-Petrel.

Key differences and behavior

Black Storm-Petrels and Ashy Storm-Petrels are distinct in behavior and habitat. Black Storm-Petrels, adept at weather navigation, inhabit tropical and subtropical pelagic zones, rarely approaching coasts except for nesting. They feed on small fish, squid, and zooplankton, thriving at nutrient-rich feeding fronts. Ashy Storm-Petrels, in contrast, favor cool, foggy coastal climates from California to Baja, often seen in nocturnal gatherings, displaying savvy survival tactics by nesting in secluded islands. Their diet is similar but includes following ships for scraps. Black Storm-Petrels perform aerial courtship acrobatics, while Ashy Storm-Petrels engage in nighttime displays. Both rely on remote nesting sites, the former using crevices and the latter using rocky burrows. Parental roles in fostering chicks are shared in both species, but Ashy Storm-Petrels involve males in provisioning.