The following has been adapted from original text by P. Ian Mitchell in Seabird Populations of Britain and Ireland (with permission from A&C Black, London).
The black guillemot or 'tystie' is a circumpolar species, concentrated around the North Atlantic, Barents Sea, Baltic and smaller numbers around the Chukchi Sea in northern Alaska and north-eastern Siberia. Approximately half of the UK's population breeds around the Northern Isles, with the remainder confined mainly to the coasts and islands of north and west Scotland. Their distribution within the core range is determined by the availability of suitable nest cavities that are safe from land predators such as rats Rattus sp., American mink Neovison vison, stoats Mustela erminea and otters Lutra lutra. Between censuses in 1969-70 and 1985-91, there was an expansion in the range of black guillemots, in particular the colonisation of new sites around the Irish Sea, including man-made structures (e.g. harbour walls, jetties, piers), and into north-east Scotland.
The species is one of the more problematic seabirds to survey. It tends to breed away from the large seabird cliff colonies and prefers small rocky islands and low-lying, indented stretches of rocky coast. Nests are hidden in rock crevices and under boulders, which makes them extremely difficult to census during the breeding season (see below).
Conservation status
Black guillemot is currently identified as a conservation priority in the following:
- Amber listed in Birds of Conservation Concern 4 (2015 update)
- further information on Conservation Designations for UK Taxa
- Amber listed in Birds of Conservation Concern in Ireland 2020–2026
International importance
|
UK Population |
% Biogeographic Population |
% World Population |
|
38,700 Individuals |
n/a |
5.8 |
The UK population figure (rounded to the nearest hundred) was derived from data in Mitchell, P.I., Newton, S.F., Ratcliffe, N. and Dunn, T.E. (eds.) 2004. Seabird Populations of Britain and Ireland. Poyser, London. This was also the source of figures for the Biogeographic and World populations.
UK population estimates and change 1969–2002 (census data)
During Operation Seafarer (1969-70), counts were conducted along with other cliff-nesting seabirds during June. At this time of year, black guillemots are often inconspicuous. Operation Seafarer therefore underestimated the population by an unknown number. Between 1982 and 1991, as part of the SCR Census, a survey of the number of adult black guillemots was conducted between late March and early May prior to the breeding season. Surveys were carried out between 06.00 – 09.00 BST when adults congregate close inshore for courtship and mating. Such counts have been found to be the most repeatable and accurate way of assessing population size. A pre-breeding survey was repeated during Seabird 2000 throughout Britain and Northern Ireland, and thus, provided the first opportunity to examine changes in the population of black guillemots in many areas since 1982-91. The main reason for this is that the spatial scales at which counts were conducted during the SCR Census and Seabird 2000 were highly compatible.
|
|
Operation Seafarer (1969-70) |
Seabird Colony Register (1985-88) |
Seabird 2000 (1998–2002) |
|
UK Population estimate (Individuals) |
n/a |
37,745 |
38,714 |
|
% change since previous census |
n/a |
n/a |
+3 |
For census results for individual countries and Ireland, the Channel Islands and the Isle of Man see under relevant sections below.
Distribution/abundance
The Seabird 2000 census provides the most comprehensive recent assessment of the distribution and abundance of breeding seabirds. Numbers of black guillemot found in different regions, and a map showing the locations and size of colonies, is provided in the Seabird 2000 black guillemot results page.
The locations sampled during the annual Seabird Monitoring Programme provide some information on distribution and are accessible via the Seabird Monitoring Programme online database.
Annual abundance and productivity by geographical area
With reference to the regional accounts below please note the following:
Breeding abundance: graphs of abundance index with 95% confidence limits are only shown for a region where the trend produced has been deemed accurate (see methods of analysis). Where a trend was thought to be inaccurate, graphs of abundance at major colonies in a region may be shown instead, particularly if such colonies hold greater than 10% of the regional population, are monitored frequently and may thus help illustrate regional population fluctuations outwith national censuses. Occasionally, too few data have been collected regionally to produce either of these.
Productivity: graphs of estimated reproductive success (hereinafter referred to as productivity) are only shown if data analysis of productivity data produced a significant result for regional and/or year effects (again see methods of analysis). If results were not significant, then a regional mean productivity value is given. However, on some occasions, too few data are available from which to provide a meaningful average.
Note: for clarity, the Figure 1 ‘Overview of all regions’ abundance graph does not include confidence limits. These can be found in the respective regional accounts below.
Overview of all regions
Breeding abundance
Figure 1. Trends in abundance index of black guillemot 1986–2019. UK (red) and Scotland (blue). Further details, including 95% confidence limits, can be found in the sections below. Based on SMP data; view the methods of analysis.
The UK and Scotland black guillemot abundance trends are closely matched, as a large proportion of the UK population and the sites monitored are in Scotland (Figure 1). Both trends declined steeply after monitoring began in 1986, reaching a low point of approximately 60% below the baseline in 1990 however, this should be treated with caution as only a very small sample size of sites was submitted to the SMP during 1988 and 1990 resulting in very large confidence limits. The trends have been relatively stable since then, fluctuating between 35 and 55% below the 1986 baseline although they appeared to be increasing in recent years. The number of colonies monitored frequently are only sufficient to allow meaningful abundance trends to be produced for the UK and Scotland.
Productivity
Due to an insufficient number of black guillemot colonies being monitored frequently for productivity, it is not possible to produce a meaningful productivity trend for any of the regions.
United Kingdom
Breeding abundance
Figure 2. Trend in UK abundance index (solid line) of black guillemot, 1986–2019 with 95% confidence limits (dotted lines; drawing of upper limit restricted to preserve detail in the abundance index). Based on SMP data; view the methods of analysis.
The UK annual sample of black guillemots is small though appears to be representative of the population as a whole (Figure 1). Abundance derived from the sample of colonies monitored as part of the SMP has declined steeply after monitoring began in 1986, reaching a low point of approximately 60% below the baseline in 1990. However, this should be treated with caution as only a very small sample size of sites was submitted to the SMP during 1988 and 1990, resulting in very wide confidence limits. The trend has been relatively stable since then, fluctuating between 50–75% below the 1986 baseline although they appeared to be increasing in recent years. Census results also indicate that the UK population changed little (+3%) between the SCR and Seabird 2000 (no comparable data are available from Operation Seafarer).
Productivity
Productivity of black guillemots derived from regularly monitored colonies in the UK (mostly located in Orkney and in Co. Down) was approximately 1.05 chicks fledged per pair per year between 1986 and 2018. No productivity data for 2019 were submitted to the SMP.
Scotland
Population estimates and change 1969–2002 (census data)
|
|
Operation Seafarer (1969-70) |
Seabird Colony Register (1985-88) |
Seabird 2000 (1998–2002) |
|
Population estimate (Individuals) |
n/a |
37,172 |
37,505 |
|
% change since previous census |
n/a |
n/a |
<+1 |
Breeding abundance
Figure 3. Trend in abundance index (solid line) of black guillemot in Scotland, 1986–2019 with 95% confidence limits (dotted lines; drawing of upper limit restricted to preserve detail in the abundance index). Based on SMP data; view the methods of analysis.
The black guillemot population in Scotland was stable between the Seabird Colony Register and Seabird 2000 censuses with c. 37,000 individuals recorded by each census. Abundance derived from the sample of colonies monitored as part of the SMP has declined steeply after monitoring began in 1986, reaching a low point of approximately 65% below the baseline in 1990. However, this should be treated with caution as only a very small sample size of sites was submitted to the SMP during 1988 and 1990, resulting in very wide confidence limits. The trend has been relatively stable since then and showing a slight increase since Seabird 2000. However, most data collected annually are from colonies in Shetland with few data from sites along other parts of the Scottish coastline and the number of sampled colonies in any year is never large. In 2019, data from 248 sites were submitted to the SMP and showed a 15% increase in individuals since Seabird 2000.
Productivity
Productivity of black guillemots in Scotland, which is derived from regularly monitored colonies mostly located in Orkney and Shetland, was approximately 1.01 chicks fledged per pair per year between 1986 and 2012. No data have been submitted to the SMP since 2012.
England
Population estimates and change 1969–2002 (census data)
|
|
Operation Seafarer (1969-70) |
Seabird Colony Register (1985-88) |
Seabird 2000 (1998–2002) |
|
Population estimate (Individuals) |
n/a |
14 |
7 |
|
% change since previous census |
n/a |
n/a |
-50 |
Breeding abundance
England holds only a few breeding black guillemots, all located at St. Bee’s Head. Fourteen individuals were counted during the Seabird Colony Register, but numbers had halved by Seabird 2000. Ten individuals were recorded in 2011 and 2012, however, since then numbers have been decreasing with only four individuals recorded in 2018 and five in 2019.
Productivity
No systematic data on the productivity of black guillemots in the small population in England have been submitted to the SMP.
Wales
Population estimates and change 1969–2002 (census data)
|
|
Operation Seafarer (1969-70) |
Seabird Colony Register (1985-88) |
Seabird 2000 (1998–2002) |
|
Population estimate (Individuals) |
n/a |
26 |
28 |
|
% change since previous census |
n/a |
n/a |
+8 |
Breeding abundance
Only 28 black guillemot individuals were recorded in Wales during Seabird 2000, mostly around Anglesey, a similar number to that found during the Seabird Colony Register. No sites of any size are monitored frequently, so the current status of the population is unknown.
Productivity
No systematic data on the productivity of black guillemots in Wales have been submitted to the SMP.
Northern Ireland
Population estimates and change 1969–2002 (census data)
|
|
Operation Seafarer (1969-70) |
Seabird Colony Register (1985-88) |
Seabird 2000 (1998–2002) |
|
Population estimate (Individuals) |
n/a |
533 |
1,174 |
|
% change since previous census |
n/a |
n/a |
+120 |
Breeding abundance
In Northern Ireland, black guillemots increased by 120% between the Seabird Colony Register and Seabird 2000 to 1,174 individuals, probably as a result of increased use of man-made structures for nest sites. Habitat such as harbour walls and piers provided important nesting sites, and it was estimated such habitat held over twice as many nesting black guillemots during Seabird 2000 than it did during the SCR; this equated to an estimated 22% of the national population1. Extensive survey work was carried out at 23 colonies in April 2017 and 2018 which held an estimated 80% of the country's population during Seabird 20002. A total of 879 individuals were recorded, 11% less than during Seabird 2000 when 989 individuals were recorded, indicating that the breeding population of black guillemot in Northern Ireland may be in decline. In 2019, there were an insufficient number of colonies surveyed to allow an updated population status assessment to be made3.
Productivity
On average 1.02 chicks were fledged per pair per year at monitored colonies between 1986 and 2014.
A study of a colony at Bangor Marina, where most pairs nest in specially provided holes and nest boxes, has revealed losses of eggs to children and predation of eggs and chicks by brown rats Rattus norvegicus, herring gulls Larus argentatus and domestic/feral cats Felis catus. Gulls have also been seen removing sitting adults, although this has been mitigated against by reducing the size of entrance holes4. Thus, losses of young due to predators are now quite low and very few nests are deserted. Overall, productivity at this colony was 1.08 chicks per nest in 2018, slightly above the long-term average of 0.98 (1986–2018). No productivity data were submitted to the SMP in 2019.
Republic of Ireland
Population estimates and change 1969–2018 (census data)
|
|
Operation Seafarer (1969-70) |
Seabird Colony Register (1985-88) |
Seabird 2000 (1998–2002) |
Republic of Ireland Census (2015-18) |
|
Population estimate (Individuals) |
n/a |
n/a |
3,367 |
3,917 |
|
% change since previous census |
n/a |
n/a |
n/a |
+16 |
Breeding abundance
Seabird 2000 was the first national census to record numbers of pre-breeding adult black guillemots in a systematic way in the Republic of Ireland. Counts carried out in April and early May recorded 3,367 individuals. Few colonies are currently monitored during the recommended month (April), or at the recommended time of day (the first few hours after dawn). The recent Republic of Ireland Seabird Census recorded 3,917 individuals; however, this is an interim assessment. The survey covered the majority of suitable habitat around the Republic of Ireland’s coastline; however, it is incomplete5.
Productivity
On average, black guillemots fledged 1.22 chicks per pair per year at the only colony monitored, Rockabill, between 2000 and 2014. No productivity data have been submitted to the SMP since 2014.
All Ireland
Population estimates and change 1969–2002 (census data)
|
|
Operation Seafarer (1969-70) |
Seabird Colony Register (1985-88) |
Seabird 2000 (1998–2002) |
|
Population estimate (Individuals) |
n/a |
n/a |
4,541 |
|
% change since previous census |
n/a |
n/a |
n/a |
Breeding abundance
With no coverage in the Republic of Ireland during the first two national censuses, the long-term black guillemot population trend for the whole of Ireland is currently unknown. However, numbers in Northern Ireland more than doubled between the Seabird Colony Register and Seabird 2000. The population for the whole of Ireland during Seabird 2000 was 4,541 individuals. In Northern Ireland, extensive survey work was carried out at 23 colonies in April 2017 and 2018 which held an estimated 80% of the country's population during Seabird 20002. A total of 879 individuals were recorded, 11% less than during Seabird 2000 when 989 individuals were recorded. A black guillemot census in the Republic of Ireland is underway but only provisional counts of 3,917 individuals have been provided to the SMP5.
Productivity
The productivity of black guillemots throughout Ireland showed no statistically significant variation over time. On average, 1.06 chicks were fledged per pair per year at monitored colonies between 1986 and 2014. No productivity data have been submitted to the SMP by either of the two countries since 2014.
Isle of Man
Population estimates and change 1969–2018 (census data)
|
|
Operation Seafarer (1969-70) |
Seabird Colony Register (1985-88) |
Seabird 2000 (1998–2002) |
Isle of Man Census (2015-18) |
|
Population estimate (Individuals) |
n/a |
303 |
602 |
211 |
|
% change since previous census |
n/a |
n/a |
+99 |
-65 |
Breeding abundance
Between the Seabird Colony Register and Seabird 2000, numbers of black guillemots on the Isle of Man almost doubled from 303 to 602 individuals. A black guillemot census was carried out on the Isle of Man during April 2018 and recorded a total of 211 individuals, a decline of 65% since Seabird 2000. Individuals were found at 27 sites, including 11 sites that did not hold any birds during the Seabird Colony Register Census6.
Productivity
No systematic data on the productivity of black guillemots on the Isle of Man have been submitted to the SMP.
Channel Islands
Black guillemot does not breed on the Channel Islands.
UK phenology, diet, survival rates
Figure 4. Median date of laying of the first egg of black guillemots nesting at North Pier, Bangor Marina, 1986–2014. Reproduced with kind permission of J. Greenwood7.
A detailed study of black guillemots nesting at Bangor Marina has allowed data on the date of laying of the first egg to be collected. In 2014, the median date of laying for the first egg was 26th May. From Figure 4, it can be seen that 2014 was a late year for the onset of egg-laying. There is evidence that the onset of egg-laying is associated with seawater temperature with warmer springs bringing the date forward7. On average, it was calculated that the breeding season became earlier by 2.5 days for every 1°C increase in April sea-surface temperature. No phenology data have been submitted to the SMP since 2014.
Diet
No systematic data on black guillemot diet have been collected as part of the SMP.
Return rate and survival rate
No systematic data have been collected as part of the SMP.
References
1 Leonard, K. and Wolsey, S. 2014. Northern Ireland Seabird Report 2013. British Trust for Ornithology, Thetford.
2 Booth Jones, K. and Wolsey, S. 2019. Northern Ireland Seabird Report 2018. British Trust for Ornithology, Thetford.
3 Booth Jones, K. 2020. Northern Ireland Seabird Report 2019. British Trust for Ornithology, Thetford.
4 Greenwood, J. 2014. A review of black guillemots breeding at Bangor, Co. Down, 1985-2013. In: Leonard, K. and Wolsey, S. eds. 2014. Northern Ireland Seabird Report 2013. British Trust for Ornithology, Thetford.
5 Cummins, S., Lauder, C., Lauder, A. and Tierney, T. D. 2019. The Status of Ireland’s Breeding Seabirds: Birds Directive Article 12 Reporting 2013 – 2018. Irish Wildlife Manuals, No. 114. National Parks and Wildlife Service, Department of Culture, Heritage and the Gaeltacht, Ireland.
6 Hill, R.W., Morris, N. G., Bowman, K. A. and Wright, D. 2019. The Isle of Man Seabird Census: Report on the census of breeding seabirds in the Isle of Man 2017-18. Manx BirdLife. Laxey, Isle of Man.
7 Greenwood, J. 2007. Earlier laying by black guillemots Cepphus grylle in response to increasing sea-surface temperature. Bird Study, 54, 378–379.
Partners
Data have been provided to the SMP by the generous contributions of its partners, other organisations and volunteers throughout Britain and Ireland. Partners to the SMP are: BirdWatch Ireland; The British Trust for Ornithology; Department of Agriculture, Environment and Rural Affairs (Northern Ireland); Department of Environment, Food and Agriculture (Isle of Man); Department of the Environment, Climate and Communications (Republic of Ireland); JNCC; Manx Birdlife; Manx National Heritage ; The National Trust; National Trust for Scotland; Natural England; Natural Resources Wales; NatureScot; The Royal Society for the Protection of Birds; Scottish Wildlife Trust; Seabird Group; Shetland Oil Terminal Environmental Advisory Group; States of Guernsey Government; UK Centre for Ecology and Hydrology. More about the SMP partners >>
Image of Black guillemot appears courtesy of Ian Rendall ©, is subject to international copyright law and may not be reproduced in any form whatsoever.
Categories:
Published: .