Least Storm-Petrel vs Ashy Storm-Petrel

Least Storm-Petrel

Hydrobates microsoma

How to recognise a least storm-petrel?

General Appearance

The Least Storm-Petrel is a small seabird known for its compact form and distinctive flight pattern. Its plumage is predominantly sooty black or dark slate, which can appear darker under direct sunlight. On the upper wings and back, the dark feathering enhances the bird's streamlined appearance. The feet are webbed, aiding in swimming, and its beak is small and pointed, ideal for surface skimming. The tail is short and slightly notched, contributing to its agile maneuvering in flight.

Male vs Female

There is a marked similarity in the appearance of male and female Least Storm-Petrels, making sex determination challenging without close observation or scientific examination. Both sexes typically exhibit the same size and feather coloration, minimal sexual dimorphism is present. This similarity helps them avoid predators by making it difficult for them to be targeted as pairs or individuals.

Juvenile

Juvenile Least Storm-Petrels closely resemble adults in terms of shape and coloration, although they may appear slightly duller. Their feathers might lack the fully weathered sheen seen in mature individuals and could display more subtle sooty tones. Juveniles have shorter wings and may not demonstrate the same level of flight skill as adults, as they are still developing their flight capabilities and muscle strength.

Size

5.1 - 5.9 in/0.7 - 1.0 oz

Habitat

Primary habitat

The Least Storm-Petrel primarily inhabits open ocean environments, particularly across the warm and tropical waters of the eastern Pacific Ocean. It is commonly found off the coasts of Baja California and islands including the Gulf of California and the Revillagigedo Archipelago. These areas provide suitable conditions for breeding and feeding.

Additional range

Despite its preference for open seas, the Least Storm-Petrel may occasionally be sighted near coastal regions and in areas with colder waters due to migratory patterns or environmental shifts. It can adapt to varying oceanic conditions, demonstrating a broader habitat range than initially expected by scientists.

Range Map

What do least storm-petrels like to eat?

Natural diet

The Least Storm-Petrel, a small seabird, primarily feeds on marine life. Its diet consists mainly of small fish, plankton, and crustaceans, which it catches while gliding over the sea surface. During daylight hours, the bird relies heavily on lanternfish, a significant prey. Nocturnal foraging sees it consume more plankton and krill when these organisms gather near the surface. This dietary pattern is consistent throughout the year, although slight variations occur as the bird adjusts to the availability of seasonal prey in different marine environments.

Bird feeders

The Least Storm-Petrel rarely visits bird feeders as it is a purely pelagic bird, preferring remote oceanic habitats far from human activity. As such, it does not consume typical bird feeder offerings like seeds or suet. However, it is theoretically possible for it to consume small fish bits or marine-based supplements if presented. Yet such feeder interactions are improbable and not observed in standard feeder environments.

There's more to learn about Least Storm-Petrel

View full details

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.

There's more to learn about Ashy Storm-Petrel

View full details

Least Storm-Petrel

Tap To compare

Ashy Storm-Petrel

Least Storm-Petrel

Hydrobates microsoma

General Appearance

The Least Storm-Petrel is a small seabird known for its compact form and distinctive flight pattern. Its plumage is predominantly sooty black or dark slate, which can appear darker under direct sunlight. On the upper wings and back, the dark feathering enhances the bird's streamlined appearance. The feet are webbed, aiding in swimming, and its beak is small and pointed, ideal for surface skimming. The tail is short and slightly notched, contributing to its agile maneuvering in flight.

Male vs Female

There is a marked similarity in the appearance of male and female Least Storm-Petrels, making sex determination challenging without close observation or scientific examination. Both sexes typically exhibit the same size and feather coloration, minimal sexual dimorphism is present. This similarity helps them avoid predators by making it difficult for them to be targeted as pairs or individuals.

Juvenile

Juvenile Least Storm-Petrels closely resemble adults in terms of shape and coloration, although they may appear slightly duller. Their feathers might lack the fully weathered sheen seen in mature individuals and could display more subtle sooty tones. Juveniles have shorter wings and may not demonstrate the same level of flight skill as adults, as they are still developing their flight capabilities and muscle strength.

Size

5.1 - 5.9 in/0.7 - 1.0 oz

There's more to learn about Least Storm-Petrel

View full details

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

View full details

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

Visual differences

The Least Storm-Petrel (0.7-0.9 oz, 5.1-5.9 in) is significantly smaller than the Ashy Storm-Petrel (1.2-1.9 oz, 7.1-8.3 in). Visually, the Least Storm-Petrel has a darker, sooty-brown coloration, whereas the Ashy Storm-Petrel features a distinctive smoky-gray plumage. The Least Storm-Petrel has a petite beak, often blending with its dark feathers, while the Ashy Storm-Petrel's beak contrasts slightly with its ashier hue, enhancing its structured shape. In terms of patterns, the Least appears more uniform, and the Ashy appears slightly mottled in certain lighting.

Key differences and behavior

The Least Storm-Petrel (Hydrobates microsoma) and Ashy Storm-Petrel (Hydrobates homochroa) exhibit distinct behaviors and habitat preferences. The smaller Least Storm-Petrel, inhabiting tropical Pacific waters, is known for its day and night foraging on plankton and small fish, often using synched calls during nighttime activities. It breeds in isolated coastal areas, forming long-term pair bonds. Conversely, the Ashy Storm-Petrel, found in the cooler coastal regions from Northern California to Baja, is adept at performing nocturnal breeding displays to minimize predator exposure. It nests in rocky crevices, with both parents sharing chick-rearing duties. Its diet mirrors the Least Storm-Petrel's but includes squid and relies on skimming nearshore waters. Neither species frequents bird feeders, yet the Ashy Storm-Petrel sometimes scavenges near ships.