The black guillemot (Cepphus grylle) is a medium-sized seabird in the alcid family. It breeds on coasts and islands in the northern Atlantic and Pacific oceans. The black guillemot is a striking bird with jet black plumage in the summer. In winter, its upperparts become dark gray and its underparts white. The black guillemot’s relatively short, pointed bill and red legs and feet help distinguish it from other alcids.
Black guillemots nest in cavities or crevices along rocky coastlines. Their eggs are brownish with dark speckles. Chicks hatch covered in down and remain in the nest cavity until they are ready to fly at four to five weeks old. Black guillemot chicks acquire their adult plumage in the fall of their first year.
The black guillemot feeds by diving underwater to catch fish, crustaceans, mollusks, and other marine invertebrates. It is able to dive to depths of over 30 meters (100 feet) to find food. Like other alcids, the black guillemot uses its wings to “fly” underwater. It is sometimes seen swimming on the surface with one wing raised above the water.
Fun Facts About the Black Guillemot
Here are some interesting and entertaining facts about the unique black guillemot:
They Have Bright Red Feet
One of the most distinctive features of the black guillemot is its bright red feet. Their feet help them cling to rocky surfaces along the shoreline. When they are swimming and diving in the water, their red feet trail behind them.
They Nest in Unusual Places
Black guillemots nest in rocky crevices and cavities on cliffs, island shores, and manmade structures. Their nest sites include natural holes, spaces under boulders and driftwood, and cracks in piers, bridges, and buildings. The small spaces help protect their eggs and chicks from predators and weather.
The Insides of Their Mouths Are Bright Blue
When a black guillemot opens its mouth, you can see its mouth lining is a striking sky blue color. The blue mouth may help attract a mate or serve some other visual signal purpose. It definitely adds a pop of color to this crevice-nesting seabird.
They Can Swim Upside Down
Thanks to their strong legs and feet, black guillemots are able to swim upside down underwater when searching for food. Their ability to orient themselves in any direction gives them an advantage when diving and pursuing fish and invertebrates.
They Spin Their Eggs
Black guillemot parents use an unusual technique to help incubate their pear-shaped eggs in rocky cavities. They use their beaks to spin their eggs frequently. Spinning maintains contact with the brood patch and ensures even incubation. It also helps prevent embryo adhesion to the inside of the shell.
They Perform Underwater Courtship Displays
In a courtship ritual unique among alcids, paired black guillemots face each other, nod their heads, and make clicking sounds. They may also pick up rocks from the sea floor and pass them to each other. Scientists think this serves to strengthen the pair bond.
They Can Dive Over 200 Feet Deep
The black guillemot is capable of diving to depths greater than 60 meters (200 feet) in search of food. Its streamlined body shape, short wings, and heavy bones help it descend rapidly and withstand the pressure underwater. They can stay submerged for over two minutes.
They Use Their Wings to “Fly” Underwater
Black guillemots beat their wings to propel themselves swiftly when pursuing prey underwater. Their wing shape provides enough lift to let them “fly” through the water. Other alcids like puffins also “fly” with their wings for agile movement when diving.
They Have Salt Glands
Like other marine birds, black guillemots possess special glands located above their eyes that remove excess salt from the bloodstream. The glands concentrate and excrete the salt through the nostrils, allowing the birds to drink seawater and maintain fluid balance.
Their Population Is Declining
Due to threats from human disturbance, pollution, oil spills, and commercial fishing, black guillemot populations are declining in portions of the North Atlantic. Conservation efforts focused on protecting nesting sites and cleaning up coastal waters benefit guillemots and other seabirds.
They Migrate Long Distances
Some black guillemot populations undergo long seasonal migrations between breeding and wintering areas. Banded birds have been documented traveling over 1,000 miles between nesting and winter grounds. Their strong flying skills allow them to navigate these lengthy journeys.
Description and Taxonomy
The black guillemot is a medium-sized alcid in the seabird family Alcidae, which includes murres, puffins, murrelets, and auklets. Its scientific name is Cepphus grylle. The genus name Cepphus is from the Ancient Greek word for some type of seabird. The species name grylle is derived from a Scandinavian word referring to this bird.
Size and Shape
Black guillemots measure 25-28 cm (9.8-11 in) long with a wingspan of 45-51 cm (17.7-20.1 in). They weigh around 450 g (16 oz). They have short, pointed wings and a short, stout body shape adapted for diving. Their legs are situated far back on their body to provide powerful propulsion for swimming underwater.
Plumage
In breeding plumage, black guillemots are entirely black except for a large white wing patch that is visible when the wing is spread. Their black coloration extends all the way to their pale bill. In winter, their dark back feathers are edged with white, giving them a scaled appearance. Their underparts turn white in winter. At all times of year, black guillemots have bright red feet.
Gender Differences
Male and female black guillemots are identical in appearance. Females average slightly smaller in size, but the sexes cannot be differentiated based on external features.
Juvenile Plumage
Hatchling black guillemots are covered in charcoal gray down feathers. As juveniles, they have variable amounts of white in their plumage. By early fall, juveniles molt into a female-like winter plumage with white underparts. Their full adult breeding plumage does not appear until the next summer when they are around one year old.
Behavior and Ecology
The black guillemot exhibits these interesting behaviors and ecological adaptations:
Breeding
– Nest in small cavities and crevices near water
– Form monogamous pair bonds that may persist for multiple years
– Lay 2 eggs per clutch from May to July
– Both parents incubate eggs for around 30 days
– Eggs are pear-shaped with brown speckled shells
– Parents spin the eggs during incubation
– Chicks hatch covered in dark gray down
– Chicks fledge at 4-5 weeks old but continue to be fed at sea
Feeding
– Dive from surface to catch fish, crustaceans, mollusks and other invertebrates
– Can dive to depths over 60 m to find food
– Swim underwater using wings for propulsion and maneuvering
– Have been recorded diving for over 2 minutes
– Surface often with prey in bill
Migration
– Northern populations migrate south in winter, some traveling over 1,000 miles
– Return to same breeding sites in spring
– Migratory flights occur both day and night
Threats and Conservation
– Populations declining in parts of range due to human disturbance, pollution, oil spills
– Listed as Near Threatened on IUCN Red List
– Protected under Migratory Bird Treaty Act in U.S. and Canada
– Conservation efforts aim to protect breeding sites and reduce pollution
Range and Habitat
Black guillemots are found along coasts and islands in the northern Atlantic and Pacific oceans. Their breeding and wintering ranges are:
Breeding
– Coastal Alaska south to Washington state
– Canada: Arctic islands south to Quebec
– Northeast U.S. from Maine to New Jersey
– Iceland, UK, northern Europe to Baltic and White Sea
Wintering
– Alaska, northern Canada, Greenland, Iceland, and northern Europe
– Some migrate south to Pacific Northwest, southern Canada, Great Lakes, and northern Atlantic coast
Habitat
– Nest along rocky shorelines, cliffs, and islands
– Forage in nearshore waters and bays
– Require access to undisturbed nest sites and clean waters with abundant food
Diet and Feeding
The black guillemot is a piscivorous seabird that feeds mainly on fish and marine invertebrates obtained by diving underwater.
Primary Prey Includes:
– Small fish such as sand lance, capelin, herring, and cod
– Crustaceans including shrimp, crab, and amphipods
– Mollusks like squid, octopus, mussels, and clams
– Marine worms and echinoderms
Foraging Behavior:
– Dive from surface to depths over 60 m in search of food
– Use wings to propel themselves swiftly underwater
-Swim on back or upside down when pursuing prey
– Seize food in bill once close enough to capture
– Consume small fish underwater but bring larger prey to surface
– Often forage in small groups or with mate
Feeding Habits by Season:
– Invertebrates important in spring before fish migrate in
– Switch to schooling fish like herring and sandlance in early summer
– Target young of year fish in shallow nursery areas
– Take cod and other bottom fish in late summer and fall
– Winter diet includes crustaceans, mollusks, and any available small fish
Diet Studies:
Research on the composition of black guillemot diet has shown:
Location | Primary Prey |
---|---|
Gulf of Alaska | Sand lance, crustaceans, rockfish |
Newfoundland | Capelin, sand lance, herring |
Maine | Herring, rock crab, winter flounder |
Baltic Sea | Herring, sprat, sticklebacks |
This table summarizes some key regional and seasonal differences in the black guillemot’s diet. Fish species like herring, sand lance, and capelin are consistently important prey across their range. But locally abundant fish and invertebrates are also heavily utilized.
Reproduction and Life Cycle
Black guillemots have an extended reproductive cycle adapted to their cliffside nesting habits. Here are details on their breeding biology and life cycle:
Sexual Maturity
– Reach breeding age at 2-3 years old
– Form monogamous pair bonds for breeding
– Display courtship rituals like underwater circles and head nodding
Nest Site Selection
– Select rocky crevices or holes for nest sites
– Nest in natural cracks and cavities on cliffs, bluffs, talus
– Also use spaces under rocks, driftwood, piers, buildings
– Require concealed sites safe from most predators
Egg Laying and Incubation
– Lay 2 eggs from May to July depending on latitude
– Eggs are pear-shaped with brown speckling
– Parents incubate eggs for 30 days by shuffling and spinning them
– Both sexes develop brood patches for incubating eggs
Hatching and Chick Rearing
– Eggs hatch asynchronously around July
– Semiprecocial chicks covered in dark gray down
– Chicks fed whole fish by parents at nest for 4-5 weeks
– Parents continue feeding chicks at sea until independence
Fledging and Immaturity
– Chicks depart nest site by jumping/gliding to water by 5 weeks
– Fledglings incapable of sustained flight initially
– Juveniles molt to immature winter plumage in fall
– Take 2-3 years to acquire adult breeding plumage
Population Status and Conservation
The global population of black guillemots is estimated at 1.5 to 3 million breeding pairs. However, some regional populations have declined, leading to an IUCN conservation status of Near Threatened.
Population Trends:
– Decreasing at rate of 10-30% over three generations in parts of range
– Declines observed in UK, Canada, USA, possibly linked to climate change
– Other populations remain widespread and stable
Major Threats:
– Disturbance and destruction of nesting sites
– Oil spills affecting birds and food sources
– Overfishing reducing prey populations
– Ocean pollution and plastics ingestion
– Climate change impacting distribution of prey fish
Conservation Actions:
– Protect and monitor breeding colonies
– Prevent oil spills and pollution near nesting areas
– Sustainable management of fish stocks
– Reduce entanglement in fishing gear
– Mitigate climate change and ocean acidification
Legal Protections:
– Listed under Appendix II of CITES treaty
– Protected by Migratory Bird Treaty Act in U.S.
– Classified as a Migratory Nongame Bird of Management Concern in U.S.
– Protected under various national laws and directives across range
Conclusion
In summary, the distinctive black guillemot exhibits many fascinating behaviors and adaptations for its cliff-nesting, fish-diving way of life. Some cool facts include its bright red feet, ability to swim upside down, and elongated breeding cycle. Major threats come from human impacts on its coastal habitat and prey species. Continued conservation efforts are needed to ensure healthy populations of this iconic seabird. Learning more about unique species like the black guillemot can inspire people to protect our amazing marine biodiversity.