Seabird diet analysis suggests sudden shift in the pelagic communities of the subtropical Northeast Atlantic

The dynamics of the subtropical pelagic ecosystems Northeast Atlantic are still poorly known due to high costs associated with sampling large oceanic areas. Top predators can be used as alternative low-cost samplers and indicators temporal variability such systems. To study variation in composition species through time broad Canary current region, we analysed foraging trips regurgitations Cory's shearwaters Calonectris borealis nesting on Selvagens islands, 2008–2011 2016–2018. Fisheries data, oceanographic variables North Oscillation were explored possible explanatory for trends behaviour diet. shearwaters' diet, complemented by fisheries revealed marked changes fish communities. In 2016 there was a peak abundance chub mackerel Scomber colias, followed an explosive increase Longspine snipefish Macroramphosus scolopax 2017 2018, deduced from diet shearwater, supported area surrounding islands. Oceanographic did not show fluctuations correlated these shifts availability, causes which remain largely unknown. This highlights importance Madeira/Canary region exemplifies efficiency avian revealing rapid communities domains. Such variations need better monitored understood measure impact ongoing global sustainably manage marine environment resources.