Observations of a novel predatory gull behavior on an invasive ascidian: A new consequence of coastal urban sprawl?

Abstract

Coastal urbanization has a dramatic effect on both terrestrial and marine ecosystems, altering resources such as food or space. Many species have shifted their ranges in response to anthropogenic pressures, resulting in novel species interactions. Here, we report an observation of a novel foraging behavior of the European Herring Gull (Larus argentatus): the capture and consumption of the widespread sea squirt Ciona intestinalis from under floating pontoons in a recreational marina in Ireland. Multiple gulls were observed performing a complex, multi-step manipulation of several C. intestinalis individuals to remove their cellulose-based tunic, which remained unconsumed. Further avenues of investigation are discussed, and hypotheses concerning possible ecosystem effects of novel ecological interactions occurring in proliferating artificial environments are presented.