Great Skua (Catharacta skua): vulnerability to climate change
Evidence for exposure
Potential changes in breeding habitat suitability:
-
Current breeding area that is likely to become less suitable (78% of current range)
-
Current breeding area that is likely to remain suitable (19%)
-
Current breeding area that is likely to become more suitable (3%)
Current impacts to Great Skuas attributed to climate change:
-
Negative Impact: Hotter summers result in increased heat stress in adults and chicks. Adults more frequently desert the nest to thermoregulate, which results in higher chick mortality from both direct and indirect causes (see increase in avian predation).
-
Negative Impact: Hotter summers result in higher chick predation rate and lower fledgling rates as adults leave the nest more frequently to thermoregulate, leaving chicks vulnerable
-
Negative Impact: Changes in prey availability during the breeding season has led to decreased fledgling success
-
Positive Impact: Changes in prey availability has led to increased population size
Predicted changes in key prey species:
No key prey species are predicted to decline for this species.
Sensitivity
-
Skuas are sensitive to high temperatures, and their southern range limit is likely defined by maximum temperature. Climate change is likely to make the southern most populations unviable in the future.
-
Parasitism and predation of seabirds is an important part of skua diets, and climate change may heavily impact their prey species. In addition, they often cannibalise their neighbours, and this behaviour may increase as alternative prey becomes scarce.
-
This species has a long generation length (>10 years), which may slow recovery from severe impacts and increases population extinction risk
Adaptive capacity
-
Great skuas have very varied diets and foraging strategies and will change their diet depending on availability. This flexibility may mean skuas can mitigate the impact of losing key prey species.
-
Great skuas are able to establish and colonise new areas, and have already done so at the northern edge of their range. They may be able to shift their range in response to climate change.
