Shag diet diversifies with rising sea temperatures

20/11/2017

A new study has found that sea surface temperatures have a direct impact on the diet of European Shag, highlighting problems that future climatic warming and resultant sea surface temperature increases might impose on its populations.

Long-term changes in climate are affecting the abundance, distribution and phenology (or seasonal timing of life habits) of species across all trophic levels (or discrete hierarchies in an ecosystem). Short-term climate variability is also having a profound impact on species and their interactions. Crucially, species will experience long- and short-term variation simultaneously, and both are predicted to change, yet studies tend to focus on only one of these temporal scales. Apex predators are sensitive to long-term climate-driven changes in prey populations and short-term effects of weather on prey availability, both of which could result in changes of diet.

The study investigated temporal trends and effects of long- and short-term environmental variability on chick diet composition in a North Sea population of European Shags between 1985 and 2014. The proportion of their principal prey, Lesser Sandeel, declined from 99 per cent (1985) to 51 per cent (2014), and estimated sandeel size declined from 104.5 to 92.0 mm over the same time period.

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