Cepphus grylle (Linnaeus, 1758)
Family: Charadriiformes > Alcidae
Found around the rocky coasts of Ireland and north-west Britain, this distinctive little seabird has a sharp black bill and scarlet feet.
In summer the Black Guillemot is all black, save for prominent white wing patches. In winter the plumage becomes almost white below with upperparts barred black-and-white. It is one of our smaller auks, only slightly larger than a Puffin and it has a thin whistling call
The Black Guillemot is one of our most sedentary seabirds, only moving a short distance offshore in winter. The provision of nest boxes sited within harbour walls has helped this species.
Select a topic for more facts and statistics about the Black Guillemot
Black Guillemot identification is usually straightforward. The following article may help when identifying Black Guillemot.
Summer Auks, in breeding plumage, at the shore or near to their colonies are relatively easy to identify. But in autumn and winter we tend to see them flying rapidly past, far offshore, or bobbing around in heavy seas offering poor views. When you add to this that their distinctive breeding plumage and colouring is lost, winter Auks can be a serious challenge to identify and separate.
Listen to example recordings of the main vocalisations of Black Guillemot, provided by xeno-canto contributors.
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Status and Trends
Population size and trends and patterns of distribution based on BTO surveys and atlases with data collected by BTO volunteers.
This species can be found on the following statutory and conservation listings and schedules.
Black Guillemots nest within rock crevices rather than in the open amongst other seabirds within cliff nesting colonies, and hence they are difficult to survey and counts were incomplete during the initial Seabird Census in 1969–70. The population remained broadly stable between the 1985–88 Census and Seabird 2000 (1998–2002) and annual data from the Seabird Monitoring Programme suggest it has been stable subsequently. Results from the recent Seabirds Count (2015–2021) are expected to offer a more comprehensive assessment of the recent trends (JNCC 2022 or link to website).
Black Guillemots are highly sedentary and their principal range in both seasons is the coasts of Ireland, Anglesey, the Isle of Man and northern and western Scotland. In winter there are additional scattered records along the coasts of the North Sea and southwest and southern England, perhaps reflecting limited dispersal away from breeding areas.
Occupied 10-km squares in UK
|No. occupied in breeding season||395|
|% occupied in breeding season||13|
|No. occupied in winter||403|
|% occupied in winter||13|
European Distribution Map
Breeding range change is most noticeable in the west of Scotland when compared with both of the previous atlases, with losses predominating in the Outer and Inner Hebrides, but striking gains are shown in the inner north Clyde area and on the east side of the Kintyre Peninsula.
Change in occupied 10-km squares in the UK
|% change in range in breeding season (1968–72 to 2008–11)||-5.5%|
|% change in range in winter (1981–84 to 2007–11)||+2.7%|
Black Guillemots are recorded throughout the year, though more consistently during summer at suitable coastal breeding sites.
Information about movement and migration based on online bird portals (e.g. BirdTrack), Ringing schemes and tracking studies.
Lifecycle and body size information about Black Guillemot, including statistics on nesting, eggs and lifespan based on BTO ringing and nest recording data.
View number ringed each year in the Online Ringing Report
|Maximum Age from Ringing||24 years 8 months 19 days (set in 2019)|
|Typical Lifespan||11 years with breeding typically at 4 year|
|Wing Length||Adults||164.6±4.7 | Range 157–174mm, N=43|
|Body Weight||Adults||409±36.33 | Range 360–480g, N=35|
Feather measurements and photos on featherbase
|Field Codes||2-letter: TY | 5-letter code: BLAGU | Euring: 6380|
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Interpretation and scientific publications about Black Guillemot from BTO scientists.
Causes of change
Unlike other auks, Black Guillemots tend to remain close to their breeding colonies when foraging and the stable trend suggests that conditions have remained reasonably favourable over the last 30 or 40 years. However, knowledge of the breeding ecology is limited in comparison to many other seabird species and therefore further knowledge of this species would be valuable in order to understand possible threats.
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