Ivory gull (Pagophila eburnea)
The ivory gull is a high-Arctic species that is associated with ice-filled waters throughout the year. The species is found in north-eastern Canada, Greenland, Svalbard and Russia. The global breeding population is estimated at approximately 14,000 pairs. The species finds its food at the edges of drift ice, but it can also exploit the remains of polar bear prey. In Svalbard, the ivory gull nests in relatively small, scattered colonies, mainly in the east of Spitsbergen, on Barentsøya and on Nordaustlandet. Monitoring of the breeding population in Svalbard shows an annual decline of about 3% a year since monitoring started in 2009.
What is being monitored?
The number of breeding pairs of ivory gulls in Svalbard
Development of the ivory gull population in 32 selected colonies, stated as a percentage of the average for the entire monitoring period. Monitoring of ivory gulls in Svalbard shows a decline in the breeding population of approximately 3% per year. The decline is seen in the context of the decline in the species' primary habitat – sea ice.
Cite these data
Norwegian Polar Institute (2021). The number of breeding pairs of ivory gulls in Svalbard. Environmental monitoring of Svalbard and Jan Mayen (MOSJ). URL: http://www.mosj.no/en/fauna/marine/ismaake.html| Unit | Data supplier | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Svalbard | % | Norwegian Polar Institute | 100 | 113 | 116 | 100 | 72 | 84 | 80 | 92 | 86 | 52 | 67 | 70 |
Method
A selection of 32 nesting colonies is visited late in the breeding season and early in the juvenile period, on foot or by snowmobile or helicopter. The number of occupied nests is recorded by two observers, as well as being documented with photographs. If work is done from a helicopter, the necessary distance from the colony is kept so that the birds do not leave the nests. The species can change nesting sites from year to year and it is therefore necessary to monitor a large number of colonies in order to discover whether the changes in numbers that are observed are due to movements between colonies.
Quality
The method is used in the four countries that have breeding populations of ivory gulls (Canada, Greenland, Norway and Russia).
Other metadata
All data is stored in the Norwegian Polar Institute's seabird database. Aggregated data is also stored in the SEAPOP databases.
Status and trend
Monitoring of ivory gulls in Svalbard shows a decline in the breeding population of approximately 3% per year since 2009. This trend is considered to be serious, given the population size of the species and its limited global distribution. However, the time series is short (12 years) and we lack basic knowledge about the species' biology. Caution should therefore be exercised in interpreting the data series. The decline in Svalbard is in line with similar trends in Canada and Greenland, where the species is also in decline.
Causal factors
The decline in the breeding population is seen in the context of an ongoing reduction in the species' primary habitat – sea ice – and high levels of environmental toxins. However, the direct links are unclear. A decline of 80% has been documented in the Canadian breeding population. The species has also disappeared from the southernmost breeding grounds in Greenland.
Consequences
About the monitoring
The ivory gull is monitored because the species is vulnerable to climate change and because such high levels of environmental toxins have been found that they could have an effect on the population size. The species is also classified as vulnerable in the Red List for Svalbard. The ivory gull is considered an ice-dependent species because it finds most of its food in the drift ice and remains in ice-filled waters throughout the year.
Places and areas
Monitoring is performed in 32 selected nesting colonies spread along the eastern side of Spitsbergen from Hornsund to Sorgfjorden, on Barentsøya and on Nordaustlandet.
Relations to other monitoring
- Monitoring programme
- International environmental agreements
- Voluntary international cooperation
- Related monitoring