Boyd's Shearwater

Puffinus boydi

Order: Procellariiformes / Family: Procellariidae

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black white small seabird coastal nocturnal migratory colonial rare endangered

About the Boyd's Shearwater

Boyd's Shearwater, scientifically named Puffinus boydi, is a seabird that belongs to the family Procellariidae. This species is primarily found in the eastern Atlantic Ocean, where it breeds on the Cape Verde Islands. The bird plays a significant role in the marine ecosystem as a predator of small fish and squid, helping to maintain a balanced food web. Its ecological importance is further highlighted by its role as prey for larger avian predators, thus contributing to the dynamic marine food chain. Boyd's Shearwater is adapted to a life predominantly at sea, coming to land only to breed. During the breeding season, it frequents the rugged cliffs and rocky islets of Cape Verde, where it nests in crevices and burrows. Outside the breeding season, the bird disperses widely across the Atlantic Ocean, demonstrating a highly pelagic lifestyle. This shearwater's migration patterns are largely influenced by the availability of food sources, which include fish and cephalopods. Seasonal changes in ocean currents and water temperatures also affect their distribution. As a result, Boyd's Shearwater serves as an indicator of oceanic conditions and changes in marine biodiversity. The bird's presence in various marine environments underscores its adaptability and significance as a species within its habitat.

The Boyd's Shearwater belongs to the family Procellariidae, within the order Procellariiformes. These birds typically live average 12 years with max recorded 18 years.

How to Identify a Boyd's Shearwater

Boyd's Shearwater can be identified by its striking plumage, with dark brown to black upper parts and contrasting white underparts. The bird's wings are long and narrow, typical of shearwaters, aiding in its efficient gliding flight over the ocean. The face is marked with a distinctive dark cap and a white throat, creating a stark contrast. Juveniles closely resemble adults but may exhibit slightly duller plumage. There is little sexual dimorphism, meaning males and females appear similar. However, males may be marginally larger. This species can be confused with other shearwaters such as the Manx Shearwater, but Boyd's Shearwater is generally smaller and has a more rapid flight pattern. In flight, the bird's silhouette is characterized by its long wings and streamlined body, enabling it to navigate the open sea effectively. While perching, Boyd's Shearwater maintains a horizontal posture, often resting on the water's surface.

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Boyd's Shearwater Habitat and Range

Preferred Habitat

Boyd's Shearwater inhabits coastal and pelagic zones of the eastern Atlantic Ocean. The bird breeds on the Cape Verde Islands, preferring rocky cliffs and islets for nesting. It is rarely found inland and avoids densely populated urban areas. During non-breeding seasons, it disperses across the Atlantic, favoring open ocean environments. These birds exploit areas with rich marine resources, often following nutrient upwellings and oceanic fronts. The shearwater's habitat preferences highlight its reliance on marine ecosystems, specifically those with abundant small fish and squid, which constitute its primary diet.

Geographic Range

Boyd's Shearwater breeds exclusively on the Cape Verde Islands, located off the western coast of Africa. During the non-breeding season, it disperses throughout the eastern Atlantic Ocean. They are primarily pelagic outside of the breeding period, venturing into international waters. The migration corridor encompasses a wide area, extending from the Canaries to the Azores and occasionally reaching as far as the western waters of the North Atlantic. The population is most concentrated around Cape Verde during the breeding season, where they form dense colonies.

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What Does the Boyd's Shearwater Eat?

Boyd's Shearwater primarily feeds on small fish and squid, which it captures by plunge-diving and surface-seizing techniques. This bird is an opportunistic forager, often taking advantage of schools of fish driven to the surface by predators. The diet varies seasonally depending on prey availability, with a preference for sardines and lanternfish during certain times of the year. Prey size typically ranges from 5 to 15 cm in length. The shearwater usually feeds during the daytime, often in mixed-species flocks, which helps increase foraging efficiency.

Boyd's Shearwater Behavior and Social Structure

Boyd's Shearwater displays a range of social behaviors, particularly during the breeding season when it forms large colonies on the Cape Verde Islands. These colonies are often situated on steep cliffs or rocky isles, providing protection from predators. Courtship involves synchronized flight maneuvers and mutual preening between pairs. The species is generally monogamous, with pairs reuniting each breeding season. Boyd's Shearwater is primarily nocturnal when on land, minimizing the risk of predation. At sea, it exhibits solitary or small group foraging behavior, although larger flocks may form over rich feeding grounds. The bird's daily activities revolve around foraging, interspersed with periods of rest on the water.

Boyd's Shearwater Nesting and Reproduction

Boyd's Shearwater nests in burrows or rock crevices on the Cape Verde Islands. The nesting sites are typically located on steep, inaccessible cliffs, which provide protection from land predators. The bird lays a single egg per season, with both parents sharing incubation duties over approximately 50 days. After hatching, the chick remains in the nest for about 70 days, with both parents involved in feeding and protecting the young. Boyd's Shearwater usually raises only one brood per year. Parental care is intensive, as both adults are responsible for feeding the chick until it fledges.

Boyd's Shearwater Sounds and Vocalizations

Boyd's Shearwater vocalizations are primarily heard at night on breeding grounds. The primary call is a repetitive cooing sound, often described as a series of low-pitched 'oo-oo' notes. These calls are crucial for mate recognition and territory establishment. Alarm calls consist of harsher, more abrupt sounds, used when predators are near. Outside the breeding season, the bird is mostly silent at sea, although it may emit soft calls while foraging in flocks.

Interesting Facts About the Boyd's Shearwater

1Boyd's Shearwater can fly over 1,000 kilometers in a single day while foraging at sea.
2The bird's nocturnal behavior on land helps it avoid predation by gulls and other daytime predators.
3Boyd's Shearwater relies on its keen sense of smell to locate food patches in the vast ocean.
4During courtship, these shearwaters engage in aerial displays that can last for several minutes.
5The species is named after British ornithologist Arnold Boyd, recognizing his contributions to bird study.
6Boyd's Shearwater chicks have a high fat content, enabling them to withstand long fasting periods.
7Despite their pelagic lifestyle, these birds exhibit strong site fidelity, returning to the same nesting sites annually.

Boyd's Shearwater Conservation Status

The IUCN lists Boyd's Shearwater as Near Threatened, with populations showing a stable trend. Primary threats include habitat degradation on breeding islands and accidental capture in fishing gear. Conservation efforts focus on habitat protection and minimizing bycatch. Recent initiatives aim to control invasive species on the Cape Verde Islands, crucial for safeguarding nesting sites. Historical population estimates suggest a decline due to human activity, but current measures aim to stabilize and hopefully increase their numbers.