Long-term dataset reveals declines in breeding success and high fluctuations in the number of breeding pairs in two skua species breeding on King George Island

Population decline of the cape petrel (Daption capense) on King George Island, South Shetland Islands, Antarctica

“…Both species use the same food source in the study area (Creet et al 1994;Casaux et al 1998;Reinhardt et al 2000). Therefore, it is likely that local prey availability has varied considerably over recent years with, in consequence, major effects on the two predator species (Krietsch et al 2016). We therefore conclude that reduced food availability is the main cause of the cape petrel collapse.…”

“…This was confirmed by Weidinger (1998a) in several nearby cape petrel colonies. However, the brown skua population in the study area was stable over the years of cape petrel collapse (Krietsch et al 2016) and thus predation alone is unable to explain the sudden decline in one prey species when others are unaffected. In addition, because skuas are generalist feeders, they are easily able to switch to other prey and alternative prey are abundant in the area as several seabird species breed there (Braun et al 2017).…”

“…The current decline in the cape petrel population on the Fildes Peninsula is not matched by declines in populations of other seabird populations in the area, namely Adélie penguin (Pygoscelis adeliae), chinstrap penguin (Pygoscelis antarcticus), gentoo penguin (Pygoscelis papua), southern giant petrel, and kelp gull (Braun et al 2020). However, the petrel decline does correspond with major fluctuations in the number of south polar skua breeding pairs in the area and repeated breeding failures of this species (Krietsch et al 2016). Repeated breeding failures in south polar skuas indicate a drastic shortage in prey availability (Krietsch et al 2016).…”

“…However, the petrel decline does correspond with major fluctuations in the number of south polar skua breeding pairs in the area and repeated breeding failures of this species (Krietsch et al 2016). Repeated breeding failures in south polar skuas indicate a drastic shortage in prey availability (Krietsch et al 2016). South polar skuas share the surface feeding behaviour of cape petrels and their diets considerably overlap.…”

The ecological value of long-term studies of birds and mammals in Central America, South America and Antarctica

“…An impressive number of long-term population monitoring studies on Antarctic seabirds have been sustained, all for 30 or more years ( [69][70][71][72][73][74][75]; Table 1; Fig. 2).…”