Status Assessment 2025 - Ivory Gull

Confidence

High

Background Information

Year added to OSPAR list: 2008 (OSPAR Commission, 2009)

• Original evaluation against Texel-Faial criteria: The ivory gull was nominated for inclusion on the OSPAR list with particular reference to “regional importance, rarity, decline and sensitivity criteria, with information also provided on threat” (OSPAR Commission, 2009).
• Global/regional importance: At the time of listing, it was estimated that there were 2000-3000 breeding pairs of ivory gulls Region I, accounting for < 25% of the world population.
• Population decline: Before inclusion in the OSPAR list, historical evidence indicated that the global ivory gull population was declining. Population status and trend were poorly documented for Region I.
• Sensitivity: The ivory gull is very sensitive to long-term adverse conditions, because: 1) it is a long-lived species, 2) it has a slow reproductive rate with only 1-2 eggs per clutch and 3) it is an opportunistic breeder that will skip breeding if food conditions are poor. Because of this, the size of local breeding populations may fluctuate between years. The total ivory gull population may show less pronounced annual fluctuations, but it will be slow to recover from a decline.
• Anthropogenic pressures and biological factors: 1). The ivory gull is a high-Arctic seabird that is closely associated with sea ice throughout the year. It is extremely vulnerable to climate warming and rapid disappearance of its main habitat. 2). The ivory gull has a high trophic position in the Arctic marine food web and is exposed to high levels of environmental pollutants. 3). The ivory gull may be negatively impacted by intensified human activity associated with an increasingly ice-free Arctic.
• Last status assessment: The last status assessment recommended that the ivory gull should be added to the OSPAR list because of its “small population size within Region I, limited number of breeding locations, population decline, and the likelihood of suffering further declines due to climate change, environmental pollution, and lack of conservation measures” (OSPAR Commission, 2009).

Geographical Range and Distribution

Within Region I, ivory gull breeding colonies can be found at high latitudes (Strøm et al., 2019; Figure 1) in east and north-east Greenland, Svalbard (Norway) and the western islands of Franz Josef Land (Russia). Although there are no significant wintering areas in the Barents Sea or along coast of East Greenland (except for a small area off the coast of Southeast Greenland, Gilg et al., 2010), there is an important staging area north of Svalbard and Franz Josef Land (80-85°N). This area extends from the Fram Strait to the Laptev Sea (off Severnaya Zemlya) and is used in September and October before the start of autumn migration (Gilg et al., 2010). Birds from Region I mostly winter in the Davis Strait and Labrador Sea, where they forage close to the sea ice edge. This area is also used by birds from Canada and Russia and is therefore of great international importance for the species (Spencer et al., 2016). It should be noted however, that while most ivory gulls breeding in Region I migrate westwards and winter in the Davis Strait and Labrador Sea, some individuals migrate in opposite direction and winter in the Bering Sea (Gilg et al., 2010). Ivory gulls belong to a single Arctic-wide population. Their breeding distribution, wintering areas, staging areas, timing of migration, and migration routes all depend critically on sea-ice dynamics, making the species extremely vulnerable to climate change (Spencer et al., 2014, Gilg et al., 2016).

Method of assessment: 1a (Svalbard and Greenland), 2c,d (Russian Arctic)

Population/Abundance

Breeding pairs of ivory gulls are difficult to count, because colonies are situated in remote high-Arctic locations that are often inaccessible and hard to find. Moreover, colonies are not used each year, such that old colonies are abandoned, and new colonies are formed. Due to a lack of historical data and fragmented surveys, population numbers of ivory gulls were poorly documented. However, since the inclusion of the ivory gull in the OSPAR List of Threatened and/or Declining Species and Habitats (Agreement 2008-06) and the development of the CAFF International ivory gull conservation strategy and action plan (Gilchrist et al., 2009), collaborative research and monitoring effort has increased globally.

In 2019 a large, international aerial survey was conducted, along the coast and in nunatak areas in Region I. During this survey 2028 ivory gulls were identified in 25 occupied colonies in Greenland (Boertmann et al., 2020), whereas in Svalbard 1119 birds were counted in 55 colonies (Strøm et al., 2020). Considering the existence of some undiscovered colonies, the overall population size was estimated as 2000-2500 pairs in Greenland (Boertmann et al., 2020) and 1500-2000 in Svalbard (Strøm et al., 2020). The number of ivory gulls breeding on the western islands of Franz Josef Land, that are also included in Region I, is currently unknown. The best estimate for the whole of the OSPAR population is therefore 3500-4500 pairs. This estimate is higher than that given at the time of OSPAR listing. This is most likely due to increased research effort rather than an actual population increase. In fact, revisiting known breeding sites in 2009 and 2019 showed that the OSPAR population of ivory gulls continues to decline. It should be noted, however, that there are regional differences. In Greenland, population numbers seem to be stable (Boertmann et al. 2020; Table 1), whereas in Svalbard the population has declined by as much as 40% in recent years (Strøm et al., 2020; Figure 2).

Table 1: Results of the population survey in Greenland, comparison of 23 breeding sites visited in 2009 and 2019 (Data from Boertmann et al., 2020).

	2009	2019
Total number of birds observed (all 23 sites)	812	817
Average number of birds observed (all 23 sites)	35,4	35,5
Average no. birds per site (occupied sites only)	58,1	62,8

Method of assessment: 1a (Svalbard and Greenland), 2c,d (Russian Arctic)

Condition

Not assessed due to a lack of information on population structure, breeding performance etc. 

Method of assessment: 2d.

Threats and Impacts

The main threats to ivory gulls in Region I are climate warming and loss of sea-ice habitat, as well as high exposure to environmental pollutants. 

A northward shift of the marginal ice zone increases the distance between breeding colonies and traditional foraging areas. This can increase feeding costs (Dumas et al., 2022) and reduce breeding success and/or adult survival. This negative effect may be buffered by birds using glacier fronts as alternative feeding areas (Lydersen et al. 2014), but this would only be temporal as glaciers are also melting. Ivory gulls are also critically threatened by the disappearance of suitable winter habitat that combines appropriate sea ice conditions and sufficient day light for foraging. Given the strong links between ivory gulls and the sea ice-edge and/or areas with highly concentrated sea-ice, the species’ conservation status is unlikely to improve in the current context of climate warming.
 
Ivory gulls remain exposed to extremely high concentrations of environmental pollutants, such as mercury (Hg), organochlorides (OC), brominated flame retardants (BFR), and per- and polyfluoroalkyl substances (PFAS) that bioaccumulate in the Arctic marine food web (Miljeteig et al., 2009, Bond et al., 2015; Lucia 2016, 2017). High levels of pollution have negative health effects, as has been shown for several Arctic top-predators, including the ivory gull (Miljeteig et al., 2012). These negative health effects are likely to impact physiological control mechanisms and reduce the capacity for behavioural plasticity. This makes it more difficult for the ivory gull to cope with additional stressors associated with habitat loss and climate warming. 

Human activity (e.g. mineral and oil exploration, industrial shipping, tourism) is currently not causing much disturbance in very remote areas and is unlikely to affect ivory gull population numbers. However, this may change in the near future as the Arctic becomes increasingly ice-free and more accessible for humans.   

Method of assessment: 2b,c
 

Conservation measures

Collaborative research has taken place by the contracting parties to estimate ivory gull population size in the OSPAR region, locate the most important breeding colonies and study how often these are used. Long-term annual monitoring of production and adult survival is established in Svalbard. Moreover, satellite tracking has revealed migration routes, autumn staging areas and an internationally important wintering area (located outside the OSPAR region), while genetic studies have elucidated that ivory gulls belong to one Arctic-wide population effectively connected through dispersal.  

The ivory gull is legally protected in the whole of its distribution range. An international ”Conservation Strategy and Action Plan” (Gilchrist et al., 2008) was presented by the Arctic Council (Conservation of Arctic Flora and Fauna, CAFF) and CBIRD (CAFF’s circumpolar seabird group). The ivory gull is also listed as “Near Threatened” by the International Union for Conservation of Nature, IUCN (BirdLife International, 2018). In the OSPAR region, most ivory gull colonies and surrounding foraging areas are located in Marine Protected Areas (MPA). In Greenland, most ivory gull colonies are in the Northeast Greenland National Park. The Northeast Greenland National Park includes areas on land, fjords and marine habitat within 3 nautical miles from the coast. While it covers some marine terminating glaciers and a little of the ice edge habitat, it does not extend far enough to protect the whole foraging range of the ivory gull.
 

Conclusion (including management considerations)

The status of the ivory gull in Region I is deteriorating. Population size is small (current estimate: 3500-4500 pairs) with colonies located in a limited number of high-Arctic breeding sites in northeast Greenland, Svalbard, and the western islands of Franz Josef Land. The OSPAR population of ivory gulls is declining, especially in Svalbard where a 40% reduction in breeding pairs has recently been observed. A dramatic population decline (70-80%) has also been documented in Canada (Gilchrist and Mallory 2005, Environment Canada 2014). The species is extremely vulnerable to climate warming, because of the deterioration of its key habitat: the sea-ice. As a top predator in the Arctic marine food web, ivory gulls are threatened by high levels of contaminant exposure due to bioaccumulation of mercury and persistent organic pollutants. Disturbance related to more human activity in an increasingly ice-free Arctic may also have a negative impact on ivory gulls, although at the current scale it is not thought to influence population numbers. It is assumed that ivory gulls belong to one global population, with individuals moving frequently between breeding colonies and with most birds gathering in the Davis Strait and Labrador Sea in winter. Therefore, international collaboration, including countries outside Region I, is a prerequisite for continued monitoring and conservation management of ivory gulls.

Knowledge gaps

For conservation purposes, it is important to combine up to date survey data from the whole of the species’ distribution range, including Arctic Russia, where most colonies of ivory gulls occur (86% global population, Gilchrest et al., 2008). It is also important to investigate how ecological changes in the Davis Strait and Labrador Sea, the species’ main wintering area, may affect ivory gulls breeding in Region I. Furthermore, when assessing the status of the ivory gull, it will be important to consider multiple stressors and how they interact: climate warming, loss of sea ice habitat and contaminant exposure.

Sheet reference:

BDC2025/ivory_gull