The Black guillemot (Cepphus grylle) belongs to the Alcid family (Alcidae) along with the puffin (Fratercula arctica), the common murre (Uria aalge), the thick-billed murre (Uria lomvia), the razorbill (Alca torda) and the rare little auk (Alle alle). The Black guillemot is an arctic bird species that occupies many areas of the coastline in the north Atlantic and North America. There are five sub-species of the Black guillemot found in the world but the Icelandic sub-species Cepphus grylle islandicus is only found around Iceland.
Looks and behavior
The Black guillemot is a very dark alcid with black body feathers but a white spot on the wing and white underwing feathers that are seen during flight. The Black guillemot has a black belly but other alcids have a white belly. The bill is black and pointy but the mouth, tongue, and feet are bright red while the bird has its summer plumage. Juveniles and adults in winter plumage look alike. They have a grayish belly but a darker upper body with yellowish feet. The Black guillemot weights 14-17.6 oz and is 12-18 in length. It is a good diver like other alcids, flies fast but low over the sea and walks quite a bit around her nesting area.
Distribution and population size
The Black guillemot nests all around Iceland but is very sparse at the southcoast due to lack of good nesting sites. The main habitat is found at the shallow Breiðafjörður with abundant nesting sites in its rocky shores. Unlike other alcids, the Black guillemot does not nest in dense colonies but is sparsely distributed along the coast in between large rocks. The Black guillemot is mostly stationary in Iceland. It stays close to the shore all year round but there have been a few marked Icelandic birds spotted close to Greenland, it is mostly juveniles that roam that far.
The Icelandic population has decreased for the past years and birds moved from the mainland coast to islands and islets, The mink (Mustela vison) is one of the reasons that the Black guillemot has moved from many old nesting areas as the birds in their nests are an easy prey for the mink. Many Black guillemot also drown in lumpsucker fishingnets in the spring which are laid in shallow waters where the birds also feed. The big collapse in the sand eel population in 2005 also had a big negative impact on the Black guillemot population. Little was hunted of Black guillemots in Iceland during the years and in 2017 a hunting ban was established. The population size is not fully known but is probably 10000-15000 breeding pairs.
Did you know?
- There are five sub-species of Black guillemots in the world and the Icelandic one is a special sub-species, Cepphus grylle islandicus.
- The Black guillemot is the only alcid that lays two eggs. They become mature 4 years old and are loyal to both its companion and nesting site.
- The oldest Black guillemot was marked and recovered in Alaska, 27 years old.
- The main food items are rock gunnels and sand eels.
- The Black guillemot has been protected in Iceland all year round since 2017 as the population has decreased for the past years.
The courtship of the Black guillemot is a beautiful sight
Late February the Black guillemot starts to gather in sheltered shores to start their mating rituals. They pair for life and as other alcids the pairbonds are strong. The courtship of Black guillemot pairs is an interesting phenomenon. It resembles the waterdance of grebes (Podicipedidae) and loons (Gaviidae). They bow and brake on the ocean, dive and run on the water column. This strange behavior is a magnificent sight. This mating ritual is followed with a high pitched whistle sound which is the origin of the Icelandic name „teista“ The whistle sound is a beautiful bird-language that is fun to hear in the spring but the Black guillemot is otherwise silent.
Nesting ecology and feeding
Each pair has its own nesting site, the nest is most often in crevicles on rockyshores or between large rocks in manmade rockfences. The Black guillemot is the only alcid that lays two eggs in the nest. The eggs are white or creamy coloured with dark spots and weight about 1.8 oz each. The incubation is about 30 days.
Both parents care for the young wich stays in the nest until it goes out to sea 30-40 days old. The Black guillemot feeds mostly on sandeel (Ammodytes marinus) and rock gunnel (Pholis gunnellus) which is sometimes called butterfish or „teistu-fish“ after the Icelandic name of the Black guillemot. It also feeds on other small fishes, crustaceans, and invertebrates from the ocean.
Why is it called teista?
The Black guillemot is called „teista“ in Icelandic but also „þeisti“ or „teisti“. All these names have their origin in the whistle sound of the bird. The chicks of the Black guillemot was harvested for meat and feathers back in the old days, a tradition that is not practised today.
Cool links that tweet
Key information from the Royal Society for the Protection of Birds (RSPB)
What Oceanwide Expeditions wrote about the barnacle goose
A great page on The Wildlife Trusts’ website
How climate change will affect them by the National Audubon Society
Learn about the white-tailed eagle in Iceland
Learn more about Icelandic birds in our article section
Author: Dr. Þórður Örn Kristjánsson
Photographer: Dr. Þórður Örn Kristjánsson