In the winter of 2022–2023, hundreds of the Atlantic puffins (Fratercula arctica) appeared dead in the coast of the Canary Islands, a rare event considering their cold-living habits, normally occupying the North Atlantic Ocean. In this work, investigation about the parasites present in the Atlantic puffins found in the biggest islands of the Archipelago was carried out from a population portion. Necropsies of 39 birds were made and, during the examination of the urinary tracts, helminths were found. Morphoanatomical analysis under microscope allowed to identify them into Renicola genus with high similarity to Renicola sloanei. After that, DNA was extracted and NADH dehydrogenase subunit 1 gene were amplificated by a polymerase chain reaction method followed by sequencing and phylogenetic analysis. The molecular results demonstrated that in fact R. sloanei was the helminth parasite present in the urinary tracts of the Atlantic puffins found in the Canary Islands.
