Last updated 4 May 2023

Since the Brünnich’s guillemot (Uria lomvia) feeds on key species in the ecosystem (for example polar cod) and is so abundant, it may be a good indicator for the productivity of the ecosystem. The Brünnich’s guillemot makes up the largest proportion of the seabird biomass in the Barents Sea (over 60%). The species is considered as vulnerable (VU) in Svalbard and critically endangered (CR) on mainland Norway for the Norwegian Red List of Species 2021. It is a generalist and an important predator on capelin, polar cod, pelagic amphipods and krill.

Brünnich’s guillemots breeding at Alkefjellet, Svalbard. Photo: Malin Kjellstadli Johansen / Norwegian Polar Institute

What is being monitored?

Breeding population on Svalbard and Jan Mayen

The figure shows the trend in the breeding population of Brünnich’s guillemots in 7 selected colonies on Spitsbergen, 2 on Bjørnøya and 3 on Jan Mayen. For each colony, the population size is shown as a percentage of the average in the colony during the entire monitoring period. The time series represents active nests in delimited parts of the colony, so-called plots. The time series for the different colonies can be on different scales, therefore, by using percentage of the average the time series can be shown on a common scale.The population has declined in all the monitored colonies on Bjørnøya and Spitsbergen. The decline is around 4% per year, except for Jan Mayen, where the data series are too short to allow interpretations on population size. Because of this, the Brünnich’s guillemot is listed as Vulnerable (VU) in the Norwegian Red List from 2021.
(Cite these data: Norwegian Polar Institute (2023). Brünnich’s guillemot breeding populations, percentage of colony average. Environmental monitoring of Svalbard and Jan Mayen (MOSJ). URL:

Details on these data

Last updated4 May 2023
Update intervalYearly
Next updateApril 2024
Commissioning organizationMinistry of Climate and Environment
Executive organizationNorwegian Polar Institute
Contact personsHallvard Strøm
Sébastien Descamps


3 counts of each plot (1 count per observer) are made 1–8 times per season, from late incubating to early chick rearing period. Counts are made with 10×40 binoculars.

On Spitsbergen, counts are only conducted in the western part. Results do not necessarily apply to colonies in eastern Spitsbergen; monitoring started in eastern Svalbard in 2015, and there is not enough data yet to assess a trend.

Monitoring takes place in six colonies on the west coast of Spitsbergen: Ossian Sarsfjellet (Kongsfjorden), Fuglehuken (Forlandet), and Alkhornet, Tschermakfjellet, Grumant and Diabasodden (Isfjorden), and on Bjørnøya and Jan Mayen. Some monitoring was previously conducted in the colonies in Sofiekammen and on Amsterdamøya on the west coast of Spitsbergen, but this work has not been continued since 2001.


The method is internationally standardized (Walsh et al. 1995), and is also standardized with the SEAPOP Norwegian monitoring.

Other metadata

All data are stored in the Norwegian Polar Institute’s seabird database, and in SEAPOP’s databases.

Reference level and action level

Red List status: a 30-50% reduction in the population over the last three generations means that the species qualifies for the category vulnerable (VU) on Svalbard.

Barents Sea Management Plan (monitoring group): a reduction in the population of 20% or more during more than 5 years, or unsuccessful breeding 5 years in a row.

Status and trend

In all, 142 colonies are known in Svalbard, with a total breeding population estimation of 615,000 pairs. The largest colonies (> 100,000 pairs) are situated in the southeastern part of Spitsbergen (Koval’skifjella and Stellingfjellet) and on Hopen and Bjørnøya. More than 80 % of the Svalbard population breeds within this “triangle”.

Following a period of relative stability or increase, the breeding population of Brünnich’s guillemots has been declining by ca 4% per year since the mid-nineties. This decline has been observed in all the monitored colonies on West-Spitsbergen, Bjørnøya and Jan Mayen. An equival trend has been observed in Finnmark colonies (mainland Norway). Trends for colonies in East-Svalbard are currently unknown.

The species is listed as Critical Endangered on mainland Norway and Vulnerable (VU) on Svalbard in the Norwegian Red List from 2021.

Causal factors

The cause of the Brünnich’s guillemot decline in Svalbard is likely connected to the warming of oceans in the species’ winter habitats near Iceland and Greenland. Here the warming most likely has led to changes in the food web and different access to prey for the Brünnich’s guillemot.

Brünnich’s guillemots are hunted in Greenland, but the hunting pressure has been decreasing since 2001. Harvesting is therefore probably not causing the recent Brünnich’s guillemot decline in Svalbard, even though it contributes negatively. By-catching of guillemots in fishing gear and/or oil pollution may also contribute to the decline in the population.


All colonies of Brünnich’s guillemots monitored in Svalbard (western Spitsbergen and Bjørnøya) show signs of decline since the mid-1990s.

The number of breeding birds has declined by approximately 4% per year. This means that the size of the Brünnich’s guillemot population has probably declined by a third in the last decade, at least on Bjørnøya and western parts of Spitsbergen.

Brünnich’s guillemots play an important role in the ecology of Svalbard through their transport of large amounts of nutrients from the marine environment to the terrestrial environment, when they fertilize local areas of tundra with their guano (excrement). A reduction in the breeding population may thus reduce this nutrition “pump”, which may have consequences for the terrestrial environment.

About the monitoring

The Brünnich’s guillemot is one of the most numerous seabirds in Svalbard, and breeds in dense colonies all over the archipelago. The diet of adult Brünnich’s guillemots is more varied than that of common guillemots. It consists mainly of fish and crustaceans, but during the breeding season, chicks are essentially fed with fish, such as polar cod (the most important prey item in Spitsbergen) or capelin (the most important prey item on Bjørnøya).

Brünnich’s guillemots are thus considered to be a good indicator of the availability of pelagic fish stocks. They are also very sensitive to oil spills and by-catching in fishing nets.

Brünnich’s guillemots are monitored on Bjørnøya and the west coast of Spitsbergen since 1988, and on Jan Mayen since 2011. The size of several colonies is estimated annually in order to detect short- and long-term changes in population size. Moreover, to explain and even predict those changes, several other parameters are monitored annually. This includes the annual adult survival of Brünnich’s guillemots and breeding success.

In each monitored colony, the total number of Brünnich’s guillemots present in some study plots is counted annually. This represents the best and internationally accepted method to detect changes in a Brünnich’s guillemot colony, and thus the population size.

In addition, studies using GLS (light loggers) are used to study activity patterns, migration routes and winter ecology.

Places and areas

Fuglehuken is one of the largest Brünnich’s guillemot colony on western Spitsbergen. Ossian Sarsfjellet is located innermost in Kongsfjorden and is easily accessible from Ny-Ålesund. Bjørnøya has one of the largest Brünnich’s guillemot colonies in Svalbard, and the southernmost. Jan Mayen is an important breeding location for Brünnich’s guillemot in the North Atlantic. Colonies are spread around the entire island, but colonies in the north are particularly large. The monitoring takes place on the islands east coast, not too far from the island’s meteorological and military station.

Relations to other monitoring

Monitoring programme

International environmental agreements

  • None

Voluntary international cooperation

Related monitoring

  • Pollutants in Brünnich’s guillemot
  • Additional studies (not part of the MOSJ monitoring) have also focused on the winter foraging ecology and migration routes of Brünnich’s guillemots through the use of external loggers (e.g. temperature–depth recorders and geolocators).

Further reading



  1. Anker-Nilssen, T., Strøm, H. 2010. Nytt klima for sjøfugl? Sjøfugl – Speiler havets tilstand – Ottar 5/2010. Ottar 283: 73–81.
  2. Descamps, S., Strøm, H., Steen, H. 2013. Decline of an arctic top-predator: synchrony in colony size fluctuations, risk of extinction and the subpolargyre. Oecologia 173(4): 1271–1282.
  3. Fluhr, J., Strøm, H., Pradel, R., Duriez, O., Beaugrand, G., Descamps, S. 2017. Weakening of the subpolar gyre as a key driver of North Atlantic seabird demography: a case study with Brünnich’s guillemots in Svalbard. Marine Ecology Progress Series 563: 1–11.
  4. Frederiksen, M., Descamps, S., Erikstad, K.E., Gaston, A.J., Gilchrist, H.G., Grémillet, D., Johansen, K.L., Kolbeinsson, Y., Linnebjerg, J.F., Mallory, M.L., McFarlane Tranquilla, L.A., Merkel, F.R., Montevecchi, W.A., Mosbech, A., Reiertsen, T.K., Robertson, G.J., Steen, H., Strøm, H., Thórarinsson, T.L. 2016. Migration and wintering of a declining seabird, the thick-billed murre Uria lomvia, on an ocean basin scale: Conservation implications. Biological Conservation 200.
  5. Gaston, A.J., Gilchrist, H.G., Hipfner, J.M. 2005. Climate change, ice conditions and reproduction in an Arctic nesting marine bird: Brunnich’s guillemot (Uria lomvia L.). Journal of Animal Ecology 74(5): 832–841.
  6. Irons, D.B., Anker-Nilssen, T., Gaston, A.J., Byrd, G.V., Falk, K., Gilchrist, G., Hario, M., Hjernquist, M., Krasnov, Y.V., Mosbech, A., Olsen, B., Petersen, A., Reid, J.B., Robertson, G.J., Strøm, H., Wohl, K.D. 2008. Fluctuations in circumpolar seabird populations linked to climate oscillations. Global Change Biology 14(7): 1455–1463.
  7. Lorentsen, S.-H., Anker-Nilssen, T., Strøm, H. 2010. Bestandsutvikling hos sjøfugl. Pp. 38–46 in: Sunnana, K., Fossheim, M., Olseng, C.D. (eds.): Forvaltningsplan Barentshavet – rapport fra overvakingsgruppen 2010. Fisken og havet 1b-2010. Institute of Marine Research (IMR).
  8. Strøm, H. 2006. Brünnich’s guillemot. In: Kovacs, K.M. & Lydersen, C. (eds.): Birds and mammals of Svalbard. Tromsø, Norwegian Polar Institute.
  9. Sandvik, H., Erikstad, K.E., Barrett, R.T., Yoccoz, N.G. 2005. The effect of climate on adult survival in five species of North Atlantic seabirds. Journal of Animal Ecology 74(5): 817–831.
  10. Walsh et al. 1995. Seabird monitoring handbook for Britain and Ireland: a compilation of methods for survey and monitoring of breeding seabirds. Published by JNCC / RSPB / ITE / Seabird Group, Peterborough.