Seabird hotspot in the North Atlantic to become a protected area | Polarjournal
Long-tailed jaegers breed throughout the Arctic in the dry tundra far from the coast during the boreal summer. On their migrations, they visit the hotspot in the North Atlantic. Photo: Dr. Michael Wenger

A comprehensive study involving 79 scientists from around the world has identified an area of great importance in the North Atlantic for millions of seabirds. Efforts are now underway to designate it a protected area.

Many seabird species often travel several thousand kilometers on their migrations from their wintering grounds to their summer breeding grounds and vice versa. On their way, they encounter numerous hazards, some of them man-made, such as longlines set by fishermen or plastic waste. In addition, overfishing and the effects of climate change are also affecting food availability. According to Johannes Lang, a wildlife biologist at the University of Giessen and co-author of the study, seabirds are consequently among the most threatened vertebrate groups, with nearly half of all species experiencing population declines.

In their study, led by BirdLife International and published in the journal Conservation Letters, the international team of researchers combined tracking, phenology and population data to map the abundance and diversity of 21 seabird species. As a result, the scientists identified an area in the North Atlantic that they estimate is important for up to five million seabirds from at least 56 colonies in 16 different countries.

The hotspot is located in the middle of the North Atlantic (green) between 41° to 53° N and 32° to 42° W and is approximately 595,000 square kilometers in size. Arrows indicate the marine ecosystems the birds are travelling from to the site, labelled with name and number of species. Dashed arrows are from areas in the South Atlantic (not visible on the map). Seabird colonies are shown in circles (black = data used in analysis, white = data considered but not included in final analysis) Map: Davies et al. 2021

According to the study, all 21 species studied visited the hotspot, including species that breed in the Arctic or boreal zone. For example, Arctic terns (Sterna paradisaea), Long-tailed jaegers (Stercorarius longicaudus) and Sabine’s gulls (Xema sabini) used the area as a stopover for their migrations, north or south depending on the season, to replenish their energy reserves. Probably the most numerous were Black-legged kittiwakes (Rissa tridactyla) and puffins (Fratercula arctica), which used the hotspot during the boreal winter. Species that breed in the Southern Hemisphere also fly up to 13,000 kilometers to visit the region during the austral winter, e.g., South Polar skuas (Stercorarius maccormicki), Great shearwaters (Ardenna gravis), and Sooty shearwaters (Ardenna grisea). The hotspot is particularly important for the Great Shearwater, with 1.5 million birds present from April to September.

In the boreal winter in the period from January to March, the total number of seabirds was at its highest with about five million. Between April and June, 2.9 million birds were still in the area before the number rose again to about 4.3 million in the last three months of the year. For three species, about two-thirds of the respective global populations use the area as wintering grounds: South polar skua, Long-tailed jaeger and Sooty shearwater. Long-tailed jaegers have been equipped with small geologgers by Johannes Lang, among others.

A small geologger on the leg of the Long-tailed jaeger provides information about its migration routes. Photo: Dr. Michael Wenger

The improved electronic tracking technologies are very valuable for researching species that are difficult to survey. “These advances are also crucial for seabird conservation – for example, in planning marine protected areas for this highly threatened group,” Lang explains. In addition, the biologist says, such data contribute to a better understanding of the dynamics of marine ecosystems in the context of climate warming.

The hotspot qualifies as an Important Bird Area (IBA) and can be considered the most important oceanic foraging area for breeding seabirds in the North Atlantic, as well as one of the most important aggregations of migratory seabirds in the Atlantic. Researchers believe the hotspot should be designated as a year-round Marine Protected Area (MPA), especially in light of the fact that 17 of the 21 species studied are affected by bycatch, overfishing, energy production, pollution and climate change, with declining population numbers. The OSPAR Commission (Oslo-Paris Convention on the protection of the North East Atlantic) is considering designating the hotspot as a Marine Protected Area.

Julia Hager, PolarJournal

Link to the study: Davies, Tammy E., Carneiro, Ana P.B., Tarzia, Marguerite, et al. Multispecies tracking reveals a major seabird hotspot in the North Atlantic. Conservation Letters. 2021; e12824.

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