Barolo Shearwater

Birds Name	Barolo shearwater
Science Name	Puffinus baroli
Domain	Eukaryota
Kingdom	Animalia
Phylum	Chordata
Class	Aves
Order	Procellariiformes
Family	Procellariidae
Genus	Puffinus
Species	P.baroli

In the vast, undulating blue expanse of the North Atlantic, where the interplay of wind and wave dictates the rhythms of biological life, there exists a seabird so elusive, so taxonomically complex, and so physically diminutive that it has famously been described by pelagic enthusiasts as a “flying cross” disappearing into the trough of a swell. This is the Barolo Shearwater (Puffinus baroli), a creature inextricably linked to the volcanic archipelagos of Macaronesia—the Azores, Madeira, and the Canary Islands. To the uninitiated observer, it is merely a small, black-and-white seabird, easily lost amidst the legions of larger Cory’s Shearwaters (Calonectris borealis) or mistaken for the widespread Manx Shearwater (Puffinus puffinus) that traverses the same ocean basins. However, to the seasoned marine ornithologist and the dedicated birder, Puffinus baroli represents one of the most compelling challenges in North Atlantic ornithology.

The Barolo Shearwater is a bird of paradoxes. It is a seabird that shuns the open ocean migration strategies of its cousins, preferring a sedentary life within the subtropical gyres. It is a member of the shearwater family, yet it flies with a manic, fluttering wingbeat that recalls an auk or a puffin more than the graceful arcing of a Calonectris. It is a species that breeds in the dead of winter, raising its single chick in deep rock crevices while the rest of the northern hemisphere’s avifauna battles the cold or migrates south. And, perhaps most intriguingly, it is a taxon that has been shuffled through the halls of scientific classification for over a century, moving from a subspecies of the Southern Hemisphere’s Little Shearwater to a close relative of the Caribbean’s Audubon’s Shearwater, before finally finding its place as a distinct, endemic species of the Northeast Atlantic.

For the North American birdwatcher, the Barolo Shearwater holds a near-mythical status. It is a “mega-rarity,” a vagrant that appears only when the Gulf Stream and atmospheric anomalies conspire to push a bird thousands of kilometers from its home waters. The few confirmed records off the coasts of Massachusetts and Nova Scotia are dissected with forensic intensity by records committees and hopeful twitchers alike. To identify a Barolo Shearwater in the field is to perform a high-wire act of observation, distinguishing the “face of a ghost”—the extensive white supraloral region—from the darker visage of the Audubon’s Shearwater (Puffinus lherminieri).

This report serves as an exhaustive monograph on the Barolo Shearwater. It is designed for the serious enthusiast who seeks not just to tick a box on a life list, but to understand the organism in its totality—from the evolutionary pressures that shaped its mitochondrial DNA to the hydrodynamic drag of its wings during a pursuit dive. We will traverse its taxonomy, dissect its morphology, map its cryptic movements, and document the conservation battles being fought on the remote cliffs of Corvo and Selvagem Grande. We will explore the bird’s connection to 19th-century Italian nobility and its role as a bio-indicator for the health of the oligotrophic waters of the central Atlantic. Through this deep dive, we aim to illuminate the life of a bird that spends the vast majority of its existence vanishing between the waves.

Taxonomy: Unraveling the Puffinus Knot

The classification of the small black-and-white shearwaters of the world has historically been one of the most tangled knots in avian systematics. The Barolo Shearwater sits at the center of a debate that spans over a century of ornithological thought, moving from morphological “lumping” to molecular “splitting.” To understand Puffinus baroli, one must first understand the chaotic history of the “Little Shearwater” complex.

Historical Classification and the “Little” Shearwater Concept

For much of the 20th century, the small shearwaters of the North Atlantic were treated as subspecies of the Little Shearwater (Puffinus assimilis). The Little Shearwater was first described by Gould in 1838 from specimens collected on Norfolk Island in the Tasman Sea, thousands of miles away in the Southern Hemisphere. Under this prevailing taxonomic regime, the birds of the Azores and Canaries were classified as Puffinus assimilis baroli, while the birds of the Cape Verde Islands were classified as Puffinus assimilis boydi.

This classification relied heavily on gross morphology. All these birds shared a similar “jizz”: they were small (significantly smaller than Manx), had blue legs (unlike the pink legs of some other Puffinus), and exhibited a distinctive fluttery flight style that contrasted with the “shearing” flight of larger species. Taxonomists lumped these geographically disparate populations—from New Zealand to Tristan da Cunha to Madeira—into a single “super-species” based on convergent evolution. They looked alike because they occupied the same ecological niche (small pursuit-diving planktivores), not necessarily because they were closely related.

The Molecular Revolution: Separating North and South

The advent of mitochondrial DNA (mtDNA) sequencing, particularly of the cytochrome b gene, shattered the assimilis consensus in the early 2000s. Landmark studies led by researchers such as Austin et al. (2004) and Sangster et al. (2005) revealed a surprising phylogeographic pattern that forced a complete rewrite of the textbooks.

The genetic data indicated that the “Little Shearwater” was a polyphyletic group—a wastebasket taxon containing unrelated lineages. The key findings were:

1. Southern Hemisphere “Little Shearwaters” (P. assimilis sensu stricto) form a distinct clade linked to the Southern Ocean.

2. North Atlantic forms (baroli and boydi) are not closely related to the southern assimilis. Instead, they are sister taxa to the Audubon’s Shearwater (Puffinus lherminieri) complex of the Caribbean and tropical Atlantic.

This revelation effectively “divorced” the Macaronesian birds from their Southern Hemisphere namesakes. The North Atlantic birds were revealed to be the result of a separate colonization event, likely an ancient invasion of the Atlantic by a Pacific ancestor that subsequently speciated into the Caribbean (Audubon’s) and Macaronesian (Barolo/Boyd’s) forms.

The Species Rank Debate: baroli vs. boydi vs. lherminieri

Once separated from assimilis, the question became: are baroli and boydi subspecies of Audubon’s Shearwater, or are they distinct species in their own right? This debate has played out across various checklist committees:

• BirdLife International: Historically retained the forms baroli and boydi within the Little Shearwater complex for conservation assessment purposes, though this is changing.

• The British Ornithologists’ Union (BOU): Accepted P. baroli as a distinct species in 2005.

• The American Ornithological Society (AOS): Followed suit in 2013, recognizing the distinct status of the Barolo Shearwater.

• Clements Checklist: Treats Puffinus baroli as a full species.

The current consensus among major authorities is to treat Barolo Shearwater (Puffinus baroli) as a distinct monotypic species endemic to the Azores, Madeira, and Canaries. Its closest relative, Boyd’s Shearwater (Puffinus boydi), breeds primarily in the Cape Verde Islands. Genetic data suggests boydi is actually closer to baroli than to the Caribbean lherminieri, but they are distinct enough in morphology (Boyd’s is darker), vocalizations (Boyd’s calls are flatter and less harsh), and range (Boyd’s is tropical, Barolo is subtropical) to be treated separately.

The Marquis of Barolo: Etymology and History

The specific epithet baroli offers a fascinating glimpse into 19th-century European history. The bird was formally described in 1857 by the French naturalist Charles Lucien Bonaparte (nephew of Napoleon Bonaparte) under the binomial name Procellaria baroli.

The name honors Carlo Tancredi Falletti (1782–1838), the Marquis of Barolo. Falletti was not a field ornithologist tramping through guano-covered colonies; he was a wealthy Italian nobleman, philanthropist, and patron of the arts and sciences based in Turin. Along with his wife, Juliette Colbert, he was instrumental in the development of the Barolo wine region (the “King of Wines”) and funded numerous charitable works, including schools and hospitals. Bonaparte likely named the shearwater after the Marquis to acknowledge his patronage of natural history collections or their personal friendship. It is a reminder that the taxonomy of the natural world is often inscribed with the social networks of the human aristocracy that cataloged it.

Table 1: Taxonomic Comparison of the North Atlantic Small Shearwater Complex

Feature	Barolo Shearwater (Puffinus baroli)	Boyd’s Shearwater (Puffinus boydi)	Audubon’s Shearwater (Puffinus lherminieri)	Little Shearwater (Puffinus assimilis)
Status	Distinct Species	Distinct Species (or ssp. of lherminieri)	Distinct Species	Distinct Species
Primary Breeding Range	Azores, Madeira, Canaries	Cape Verde Islands	Caribbean, Bahamas	Southern Oceans (NZ, Australia)
Phylogenetic Affinity	Sister to boydi and lherminieri	Sister to baroli and lherminieri	Sister to baroli and boydi	Distant relative (Southern Clade)
Key ID Trait (Face)	“White Face” (Eye isolated in white)	Darker face, intermediate	Dark Face (Eye in dark cap)	“White Face” (Convergent evolution)
Undertail Coverts	White	White (usually)	Dark / Mottled	White
Flight Style	Rapid flutter-glide (“Alcid-like”)	Rapid flutter, less gliding	Flutter-glide, more shear	Rapid flutter-glide
Vocalizations	Harsh, rhythmic ka-ki-kukukur-caa	Flatter, longer inhaled note	High-pitched whistling	Distinct from N. Atlantic forms

Table 1 Insight: The convergence in appearance between the Barolo Shearwater and the true Little Shearwater (P. assimilis) of the Southern Hemisphere is remarkable. Both evolved white faces and blue legs independently, likely as adaptations to similar camouflage requirements in open ocean environments or signaling needs at the colony. This is a classic example of cryptic speciation where genetics reveals what the eye cannot see.

Description and Identification: The “Flying Cross”

Identification of Puffinus baroli is one of the supreme challenges of Atlantic seawatching. The bird is small, fast, and often viewed in suboptimal conditions—distant, amidst high swell, or in poor light. For the birder standing on a headland in Massachusetts or staring off the stern of a pelagic vessel in the Azores, understanding the minute details of “jizz” and plumage is essential.

General Appearance and “Jizz”

The Barolo Shearwater is the smallest shearwater in the North Atlantic. Its diminutive size is the first clue. When seen alongside a Manx Shearwater, the Barolo appears roughly two-thirds the size, compact, and almost “toy-like.”

• Length: 25–30 cm (approx. 10–12 inches).

• Wingspan: 58–67 cm (approx. 23–26 inches).

• Weight: 170–275 g (mean approx. 220 g). To put this in perspective, a Manx Shearwater weighs nearly double this (350–575 g).

The structure is compact. It has a rounded head, a steep forehead, and a relatively short, slender bill compared to the longer snout of a Manx or Audubon’s. The tail is short and square, unlike the longer, graduated tail of the Audubon’s Shearwater.

The flight style is perhaps the most distinctive field mark at a distance. Due to its high wing loading (small wing area relative to body mass), the Barolo Shearwater cannot glide as efficiently as larger shearwaters. Its flight consists of a rapid, frantic series of wingbeats (whirring) followed by a very short glide, often described as “alcid-like” or resembling a tiny auk. It flies low to the water, hugging the contours of the waves, and rarely shears high above the horizon unless in very strong winds.

Detailed Plumage Analysis

The “White Face”

This is the “Holy Grail” feature for identification. In a classic Barolo Shearwater, the dark cap is restricted to the top of the head and stops above the eye. This leaves the dark eye isolated in the white of the face, giving the bird a “kind,” open-faced expression. This contrasts sharply with the Manx Shearwater and Audubon’s Shearwater, where the dark cap typically extends below the eye, obscuring it. However, caution is required: some Barolos can show a slight dark smudge near the eye, and some worn Audubon’s can show a paler face. The “isolated eye” is diagnostic when clearly seen, but distance often makes this difficult to judge.

Upperparts and the “Silvery Panel”

The dorsal plumage is generally a sooty black, turning browner with wear. A subtle but critical feature is the presence of a silvery panel on the secondary coverts. In fresh plumage, the greater coverts have pale tips, creating a distinct light bar or panel on the inner wing that contrasts with the darker flight feathers. This “two-toned” wing effect is absent in Manx Shearwaters and less pronounced in Audubon’s.

Underparts and Undertail

The underparts are pristine white, extending from the chin to the undertail coverts. The white undertail coverts are a crucial distinction from the Sargasso (Audubon’s) Shearwater, which typically has dark or mottled undertail coverts. If a small shearwater shows a “black butt” (dark undertail), it is almost certainly an Audubon’s. If the undertail is white, it could be a Barolo, a Boyd’s, or a Manx.

Bare Parts

The bill is slender, blue-grey with a darker tip. The legs are a striking pale blue (often described as bluish-pink), with blackish outer toes. This blue leg color is a feature of the “Little Shearwater” group and helps distinguish it from species with clearer pink legs, though at sea, leg color is rarely visible.

Flight Mechanics and Wing Loading

The flight behavior of the Barolo Shearwater is not just a quirk; it is a matter of physics. Wing loading is the ratio of body mass to wing area ($Mass / Area$).

• High Wing Loading: The Barolo has relatively short, rounded wings. This results in high wing loading, meaning each square centimeter of wing must support more weight than in a larger shearwater with long wings.

• Consequences: To stay airborne, the bird must generate lift through frequent, rapid flapping. It cannot rely on the passive lift generated by air currents over waves (dynamic soaring) to the same extent as a Cory’s Shearwater.

• Evolutionary Trade-off: Why evolve such inefficient wings for flight? The answer lies underwater. The Barolo Shearwater is a pursuit diver. Smaller, compact wings create less drag underwater, allowing the bird to “fly” through the sea with greater agility and depth to catch squid. The bird has traded aerial efficiency for sub-surface performance.

Table 2: Biometric and Identification Matrix

Feature	Barolo Shearwater (P. baroli)	Manx Shearwater (P. puffinus)	Audubon’s Shearwater (P. lherminieri)	Boyd’s Shearwater (P. boydi)
Total Length (cm)	25 – 30	30 – 38	27 – 33	27 – 30
Wingspan (cm)	58 – 67	76 – 89	64 – 72	60 – 65
Weight (g)	140 – 275	350 – 575	150 – 230	150 – 220
Face Pattern	Eye isolated in white	Dark cap below eye	Dark cap through/below eye	Intermediate (variable)
Undertail Coverts	White	White	Dark / Mottled	White (usually)
Upperwing	Black/Brown + Silvery Panel	Uniform Black	Brown, less contrast	Dark Brown
Flight Style	Manic flutter, short glides	Shearing, long glides	Flutter-glide	Manic flutter
Tail Shape	Short, Square/Rounded	Medium	Longer, Rounded	Intermediate

Table 2 Insight: Note the significant weight difference. A Barolo Shearwater is roughly half the weight of a Manx. This huge disparity explains why they look so different in high winds; a Manx cuts through the gale, while a Barolo can appear buffeted and frantic.

Distribution, Range, and Population

The Barolo Shearwater is a true Macaronesian endemic. Its entire life cycle is bound to the subtropical islands of the Northeast Atlantic, a distribution that makes it highly vulnerable to localized threats.

Breeding Range: The Island Strongholds

The species breeds on three main archipelago systems. The distribution is fragmented, with colonies often restricted to tiny, uninhabited islets to avoid predation.

1. The Azores

The Azores are a key stronghold. Breeding is confirmed on all nine islands of the archipelago (Flores, Corvo, Graciosa, Terceira, São Jorge, Pico, Faial, São Miguel, and Santa Maria), as well as the Formigas islets.

• Status: The population here is considered stable, estimated at 840 to 1,740 pairs.

• Habitat: Nests are primarily found on predator-free islets (like the Vila Franca islet off São Miguel) or on the sheer, inaccessible cliffs of the main islands where rats cannot easily reach.

2. The Madeira Archipelago

• Madeira Island: Breeding is very rare on the main island due to high human density and invasive predators.

• Desertas Islands: These uninhabited islands (Ilhéu Chão, Deserta Grande, Bugio) support a small but important population.

• Porto Santo: Colonies exist on the surrounding islets (e.g., Cima Islet), which are critical refuges.

• Population: Estimates for the main Madeira group are low, likely under 200 pairs.

3. The Canary Islands and Selvagens

• Canary Islands: Breeding is recorded on Tenerife, La Palma, El Hierro, La Gomera, and Lanzarote (specifically the Chinijo Archipelago: Alegranza, Montaña Clara). The population is fragmented and estimated at roughly 400 pairs, with a decreasing trend.

• The Selvagens (Savage Islands): Located between Madeira and the Canaries, this tiny Portuguese archipelago is the historical epicenter of the species.

  • The Decline: Historically, the Selvagens held the largest colony in the world, with estimates of 1,383 to 3,689 pairs in the late 1990s. However, recent surveys indicate a strong decline in this stronghold. The reasons are complex but may involve shifts in ocean productivity (climate change) or predation by geckos and other native species on eggs.

Population Trends and Status

The global population is small, likely numbering between 3,000 and 5,500 breeding pairs. While the Azores population appears stable due to intensive conservation management, the collapse of the Selvagens colony is a major concern. The species is listed as Least Concern globally by the IUCN (often lumped with Little Shearwater in older assessments), but regional assessments classify it as Vulnerable or Endangered within Europe due to its small, fragmented range and susceptibility to predation.

Table 3: Estimated Breeding Population by Archipelago

Archipelago	Historical Baseline (c. 1990s)	Recent Estimates (2010s-2020s)	Trend Direction
Azores	840 – 1,530 pairs	895 – 1,741 pairs	Stable (Conservation Dependent)
Madeira (Main/Desertas)	144 – 183 pairs	< 200 pairs	Unknown/Stable
Selvagens (Savage Is.)	1,383 – 3,689 pairs	Significantly Lower	Strong Decline
Canary Islands	~400 pairs	< 400 pairs	Decreasing
GLOBAL TOTAL	~3,000 – 5,500 pairs	~2,000 – 3,500 pairs	Declining

Marine Range and “The Black Hole”

Unlike the Manx Shearwater, which undertakes a massive transequatorial migration to South America, the Barolo Shearwater is largely sedentary to dispersive.

• Post-Breeding: After fledging in late spring, adults and juveniles disperse into the wider Northeast Atlantic. Tracking studies show they utilize a massive area of the subtropical gyre, ranging from the Iberian coast south to the Canary Current and west toward the Azores.

• The “Black Hole”: Between June and December, the birds vanish into the deep Atlantic. They generally do not cross the equator and rarely cross the Mid-Atlantic Ridge in large numbers. This restriction to the “oceanic desert”—the low-nutrient waters of the central gyre—is unusual for seabirds, which typically seek out nutrient-rich upwelling zones.

Habitat and Marine Ecology

The Barolo Shearwater is an inhabitant of the oligotrophic (low nutrient) waters of the subtropical North Atlantic. This habitat choice drives much of its biology, distinguishing it from species that thrive in cold, nutrient-rich waters.

Bathymetry and Oceanography

• Deep Water Specialists: In the Azores, tracking studies reveal that Barolo Shearwaters forage over areas with very deep bathymetry. They avoid the shallow seamounts and coastal shelves that are favored by Cory’s Shearwaters and Common Terns. This habitat segregation helps reduce competition with larger, more dominant seabirds.

• Temperature Preferences: Their distribution is closely linked to Sea Surface Temperature (SST). They generally remain in waters warmer than 15°C. This thermal preference likely limits their northward expansion and keeps them separated from the colder-water foraging grounds of the Manx Shearwater.

The “Oceanic Desert” Paradox

The central North Atlantic gyre is often called a biological desert because the stable stratification of the water prevents nutrient-rich deep water from reaching the surface. How does the Barolo Shearwater thrive here? The answer lies in mesoscale eddies. These are swirling currents that can trap nutrients and concentrate prey. Barolo Shearwaters are likely adept at locating these ephemeral patches of productivity within the vast, empty ocean. Their reliance on such patchy resources makes them highly sensitive to large-scale climatic oscillations like the North Atlantic Oscillation (NAO), which can alter current strengths and prey distribution.

Feeding Ecology: The Deep Diver

One of the most fascinating aspects of Barolo Shearwater ecology is its feeding strategy. While many shearwaters are surface seize feeders, picking prey off the top of the water, the Barolo is a proficient diver, arguably the “penguin” of the shearwater family in the North Atlantic.

Diet Composition: The Squid Specialist

Stomach flushing studies from the Azores and Selvagens have provided a detailed look at the Barolo’s menu. It is specialized on cephalopods (squid) and small pelagic fish.

• Cephalopods (Squid): Squid make up the bulk of the biomass. The most diverse prey group includes at least 10 different taxa.

  • Argonautidae: The Paper Nautilus (Argonauta argo) is a top prey item. Interestingly, the birds consume mostly juvenile Argonauts (hood length <1.5 mm).

  • Onychoteuthidae: Hooked squids (Onychia sp.).

  • Cranchiidae: Glass squids.

• Fish: The family Phycidae (Forkbeards) and other small mesopelagic fish are important.

• Trophic Shift: Isotope analysis reveals a fascinating seasonal shift. During the chick-rearing period (winter/spring), parents feed at a lower trophic level (smaller, lower-chain prey) than during the non-breeding season. This suggests they target specific, abundant larval pulses to feed their chicks, or that they are constrained to local waters where high-trophic prey is scarcer.

Diving Behavior and Physiology

The Barolo Shearwater feeds deeper in the water column than its larger cousins, exploiting a niche unavailable to surface feeders like Gadfly Petrels.

• Depth Profile: They regularly dive to 15 meters, with maximum recorded depths of 23 meters. While this pales in comparison to the Sooty Shearwater (which can hit 60m), it is significant for a bird of its size.

• Pursuit-Plunging: The bird often locates prey from the air, plunges into the water, and then continues the chase underwater. Its flattened humeri (upper wing bones) and laterally compressed tarsi (legs) are adaptations for this amphibious life, serving as hydrofoils and rudders.

• Diel Vertical Migration (DVM): The Barolo is a strategic hunter. Many of its prey species (like the Argonauts and lanternfish) live deep in the ocean during the day but migrate to the surface (upper 50 cm) at night to feed on plankton. The Barolo Shearwater aligns its foraging schedule with this migration, hunting extensively at night and during twilight to intercept these rising prey items.

Table 4: Diving Depth and Prey Comparison

Species	Average Dive Depth (m)	Max Dive Depth (m)	Primary Prey	Foraging Strategy
Barolo Shearwater	5 – 14	23	Juv. Squid (Argonauta), Forkbeards	Pursuit Plunging / Diving
Cory’s Shearwater	Surface – 2	10	Fish (Scomber, Boops), Squid	Surface Seizing / Shallow Plunge
Manx Shearwater	2 – 5	55	Herrings, Sprats, Sandeels	Pursuit Diving
Sooty Shearwater	10 – 30	67	Krill, Fish, Squid	Deep Pursuit Diving

Table 4 Insight: The Barolo’s intermediate diving depth allows it to partition resources. It dives deeper than Cory’s (avoiding competition for surface fish) but doesn’t compete with the massive shoals of Sooty Shearwaters that pass through on migration. It occupies the “middle lane” of the vertical water column.

Breeding Biology: The Winter Strategy

Unlike most North Atlantic seabirds that breed in the spring and summer (May–August) to capitalize on the massive plankton blooms, the Barolo Shearwater is a winter/spring breeder. This phenological shift is a critical evolutionary adaptation.

Phenology: Against the Grain

• Return to Colony: Adults return to the breeding grounds in late summer/autumn to reclaim burrows.

• Egg Laying: Occurs remarkably early, from January to February (sometimes late December).

• Incubation: Lasts approximately 52–58 days, shared by both sexes in shifting stints.

• Hatching: March and April.

• Fledging: Juveniles leave the nest in May and June.

Why breed in winter? The leading hypothesis is Inter-specific Competition Avoidance. The Macaronesian islands are crowded. By fledging in May/June, Barolo chicks vacate the burrows just as the larger, more aggressive Cory’s Shearwaters are returning from the South Atlantic to lay their eggs. If Barolos bred in summer, the massive Cory’s Shearwaters would likely evict them from burrows or kill their chicks. By shifting their cycle 4-5 months earlier, Barolos utilize the “timeshare” property of the nesting cliffs when the larger tenants are away.

Nesting and Parental Care

• The Burrow: Nests are deep cavities in volcanic rock, lava tubes, or burrows excavated in soft soil. Barolo burrows are typically smaller and possess a narrower entrance than Cory’s burrows, offering some protection from predation.

• Nocturnal Visits: Parents visit the colony strictly at night to avoid predation by Yellow-legged Gulls (Larus michahellis) and diurnal raptors like Buzzards (Buteo buteo). They arrive under the cover of darkness, navigate by sound and smell, feed the chick, and depart before dawn.

• Foraging Range: Unlike albatrosses that leave chicks for weeks to forage thousands of miles away, Barolo parents forage relatively close to the colony during chick-rearing (within a few hundred km). They return frequently (every 1-2 nights) to deliver fresh meals. This indicates that local waters around the Azores and Canaries must be productive enough in winter to support them.

Acoustic Behavior

The colonies are silent by day but raucous by night. The call is a rhythmic, throaty series of notes: “ka-ki-kukukur-caa” or “ka-ki-kaa”.

• Sexual Dimorphism: Females have lower-frequency, harsher calls, while males produce higher-pitched, clearer whistles. This allows pairs to identify each other in the chaos of the colony.

• Comparison: Recent studies show the call is distinct from Boyd’s Shearwater, which has a flatter, less modulated call structure. This acoustic divergence helps maintain reproductive isolation.

Threats and Conservation: Protecting the Ghost

Despite living on remote oceanic islands, the Barolo Shearwater faces a barrage of anthropogenic threats that have extirpated it from many traditional breeding sites.

Invasive Predators: The Primary Threat

The introduction of non-native mammals to Macaronesia since the 15th century has been catastrophic.

• Rats (Rattus rattus, Rattus norvegicus): Rats are agile climbers that enter burrows and consume eggs and small chicks. They are the primary reason Barolos are absent from the main islands’ accessible coastlines.

• Cats (Felis catus): Feral cats prey on breeding adults. A single cat can kill dozens of adult shearwaters in a season, as the birds are clumsy and defenseless on the ground.

• The “Mesopredator Release” Effect: Conservationists must be careful; eradicating cats can sometimes lead to an explosion in rat populations, which then devastate the eggs. Integrated management is required.

Light Pollution: The “Fallout”

Fledglings leaving the nest for the first time in May/June use the moon and stars to navigate to the sea. Artificial lights from coastal towns (streetlights, hotels, stadiums) disorient them.

• Mechanism: The birds circle the lights until they become exhausted or collide with buildings/wires, falling to the ground where they are eaten by cats or run over by cars.

• Hotspots: Towns in Tenerife and the village of Vila do Corvo are hotspots for this phenomenon.

• Mitigation: Campaigns like “Save a Seabird” (SOS Cagarro) in the Azores mobilize the public to rescue downed birds, though these focus largely on Cory’s, Barolos benefit too.

Climate Change and Oceanography

The decline of the Selvagens population is particularly worrying because the islands are a Nature Reserve with no introduced predators. This suggests a marine cause.

• The NAO Connection: Research indicates that breeding success is lower in years with a negative North Atlantic Oscillation (NAO) index. Negative NAO years are associated with lower marine productivity in the region. As climate change alters the frequency of these oscillations, the Barolo’s food supply may be becoming unreliable.

Conservation Success Stories: The LIFE Projects

There is hope. The European Union’s LIFE program has funded massive restoration efforts in the Azores and Madeira.

• LIFE “Safe Islands for Seabirds” (Corvo): This project built a predator-proof fence on Corvo Island to create a sanctuary for shearwaters. They eradicated cats and rats within the enclosure and used sound systems (social attraction) to lure birds back. The result has been a stabilization of the population and high breeding success within the managed area.

• Rat Eradication: Successful eradication of rats on islets like Vila Franca (São Miguel) has allowed seabird populations to bounce back rapidly.

Table 5: Conservation Status and Action Matrix

Region	Primary Threats	Key Conservation Actions	Current Trend
Azores	Rats, Cats, Light Pollution	LIFE Priolo / Safe Islands: Predator-proof fencing, islet deratization.	Stable / Recovering
Madeira	Rats, Light Pollution	LIFE Natura: Biosecurity on Desertas; flora restoration.	Uncertain
Selvagens	Climate/Oceanography, Geckos?	Strict Nature Reserve (since 1971); Monitoring.	Declining (Cause unknown)
Canaries	Rats, Cats, Urbanization	Local control; rescue campaigns.	Declining (Critical)

Migration and Vagrancy: The North American Connection

While the Barolo Shearwater is not a long-distance migrant, its dispersal patterns bring it into the sphere of North American birding, creating moments of high excitement and complex identification debates.

The Mechanism of Vagrancy

How does a bird from the Azores end up in Massachusetts?

• The Gulf Stream: The warm waters of the Gulf Stream current act as a highway. Birds dispersing west from the Azores may get entrained in the warm water eddies (rings) that spin off the Gulf Stream.

• Weather Systems: Persistent easterly winds or hurricanes tracking across the Atlantic can blow these small, lightweight birds westward.

• Overshooting: Young birds, exploring the limits of their range, may simply travel too far west, hitting the rich waters of the continental shelf break before turning back.

North American Records

The Barolo Shearwater is a “Code 4” rarity on the American Birding Association (ABA) list. Records are concentrated in late summer (July-August), coinciding with the warmest water temperatures and the post-breeding dispersal of adults.

• Massachusetts – The Hotspot: Massachusetts waters, specifically the deep canyons south of Nantucket (Veatch, Munson, Oceanographer Canyons), account for the majority of accepted US records.

  • August 25, 2007: The watershed moment. A bird was photographed 18 miles north of Veatch Canyon. The photos clearly showed the diagnostic white face and blue legs, eliminating Audubon’s. This became the first fully accepted US record.

  • July 29, 2011: An experienced seabirder (Mike Force) documented a bird 160 miles ESE of Nantucket.

  • August 26, 2012: Another photographed record from Oceanographer Canyon.

• Nova Scotia: Documented sightings exist, often correlating with the same weather systems delivering birds to New England.

Table 6: Summary of Accepted Massachusetts Records (MARC)

Record ID	Date	Location	Evidence	Decision	Context
2007-058	Aug 25, 2007	18 mi N of Veatch Canyon	Photos	Accepted	Found during a BBC Extreme Pelagic. First confirmed US record.
2011-033	July 29, 2011	160 mi ESE of Nantucket	Sight	Accepted	Found by Mike Force on NOAA survey.
2012-155	Aug 26, 2012	Oceanographer Canyon	Photos	Accepted	Photographed by Tom Johnson; clear ID.
2018-033	Aug 13, 2018	Munson Canyon	Sight	Not Accepted	Details insufficient to rule out Audubon’s/Manx.

Table 6 Insight: The pattern is clear: late summer, deep water canyons (off the shelf), and warm water incursions. Birders seeking this species must venture far beyond the standard whale-watching grounds, often 100+ miles offshore.

Cultural Significance: The Marquis and the Bird

The Barolo Shearwater carries a name that evokes the rolling vineyards of Piedmont, Italy, rather than the salty cliffs of the Atlantic.

• Carlo Tancredi Falletti (Marquis of Barolo): The bird is named after this 19th-century nobleman. His connection to the bird is likely through his patronage of the sciences. In an era before government grants, naturalists like Bonaparte relied on the funding of wealthy aristocrats to publish their monographs and maintain their collections.

• Local Lore: In the Azores, the bird is often lumped with other nocturnal shearwaters under the name “Estapagao” (one who turns off the lights/hides), referring to its nocturnal habits. In Madeira, it is affectionately known as “Pintainho” (Little Chick), a reference to its small size compared to the ubiquitous Cory’s Shearwater.

Conclusion

The Barolo Shearwater is a testament to the power of isolation. Separated from its ancestors by vast oceans, it evolved into a unique specialist of the subtropical Atlantic—a winter-breeding, deep-diving ghost of the Macaronesian cliffs.

Its future is precarious. While the Azores populations are currently stabilized by heroic conservation efforts, the mysterious collapse of the Selvagens colony serves as a warning that local biosecurity may not be enough in the face of global oceanographic change. For the birdwatcher, the Barolo Shearwater remains one of the ultimate prizes of the Atlantic—a fleeting white-faced phantom that demands skill, patience, and a healthy dose of luck to witness. As we continue to unravel the secrets of its taxonomy and ecology, we are reminded that even the “little” birds of the world hold massive stories of evolution, adaptation, and survival.