Annual survival of Arctic terns in western Iceland

Abstract

Many seabird species in the North Atlantic region have shown considerable declines in their populations during recent decades. One such species is the Arctic tern (Sterna paradisaea), a small seabird which migrates farther than any other seabird each year and whose global population is thought to be in decline. We used banding data of chicks and adults, spanning five decades ) from a tern colony on Flatey, in western Iceland, to generate the first assessment of annual survival in this species in Iceland. Survival from just after hatching to the next summer was estimated to be 0.119 ± 0.024 (SE), while annual survival of adult birds (older than one year) was high at 0.952 ± 0.030. Although our data were insufficient to assess annual variation in adult survival, we noted a reduced survival (0.851 ± 0.034) in recent years (since 2000), coincident with a collapse in local sand lance populations. Reduced adult survival, along with other factors, is likely contributing to declining populations of this iconic species in Iceland, a country supporting 20-30% of the world's breeding population.

Adult survival and annual movement patterns of common snipe in Iceland

“…Clair et al 2010). For context, we recently examined adult survival in Arctic terns (Sterna paradisaea) and common eiders nesting on Flatey, and estimated rates were amongst the highest reported for each species (Petersen et al 2020;Wood et al 2021). The snipe apparent survival rate on Flatey could be a bit higher than elsewhere on mainland Iceland, where nesting birds may experience predation pressure from feral American mink (Neovison vison) and Arctic fox (Vulpes lagopus).…”

Foraging Behaviours of Breeding Arctic Terns Sterna paradisaea and the Impact of Local Weather and Fisheries

“…Arctic terns annually undertake the longest recorded migration of any organism (Egevang et al, 2010), travelling over 100,000 km (Volkov et al, 2017) from circumpolar breeding locations in the Temperate (southernmost at 41 • N) and Polar zones to overwintering sites in the Southern Ocean (Hatch, 2002). Populations appear to be declining at many locations across the breeding range [e.g., in Canadian High Arctic (Mallory et al, 2018), Western Iceland (Petersen et al, 2020), Greenland (Burnham et al, 2017), and Norway (Barrett et al, 2006)]. Generally there is high adult survival (Devlin et al, 2008;Mallory et al, 2018), with very high regional (Egevang and Frederiksen, 2011) and colonial breeding site fidelity (Devlin et al, 2008).…”

“…In Iceland, the collapse of sandeels (Ammodytes sp. ), a key prey species, has coincided with lower adult survival since 2000 (Petersen et al, 2020), and low fledgling rates caused by starvation (Vigfúsdóttir et al, 2013). It is therefore key to understand how and where arctic terns forage during the breeding season, and whether their behaviour alters in relation to weather and fish stocks.…”

“…In the warmer waters in the south and west of Iceland, seabirds rely mainly on sandeels, and in the cooler waters in the north and east on capelin and krill (Lilliendahl, 2009). Following the collapse of the sandeel population in 2000, annual arctic tern adult survival reduced by 10% in west Iceland (Petersen et al, 2020). The present study focuses on the foraging behaviours of arctic terns in the west and southwest regions (west of the Reykjanes peninsula and Faxaflói bay), and highlights potentially important foraging areas that are used by commercial fisheries.…”

“…Historically the pelagic fisheries in Iceland landed mostly capelin (a known prey species of arctic terns and other seabirds off the north coast of Iceland, but have not been documented in their diet in the south) for the fishmeal industry (generally greater than 80% of pelagic landings), but due to declines in capelin stocks and new, more valuable species (e.g., herring Clupea harengus and mackerel Scomber scombrus) entering Iceland's waters, capelin landings have declined recently (Saevaldsson and Gunnlaugsson, 2015). Given the importance of this area for breeding arctic terns and other seabird species (Garðarsson, 1999), the link between poor fledging success and food availability (Vigfúsdóttir et al, 2013;Petersen et al, 2020), and the increase in pelagic landings in the region (Edvardsson et al, 2018), it is important to investigate the potential impact of the fisheries industry. Addressing factors that influence arctic tern foraging success will shed light on the potential causes of the declines, which is key to preserve this population, and will also benefit the wide range of other species that breed in the rich waters around Iceland.…”