The Owl Gull: Exclusively Nocturnal Foraging by the Swallow-tailed Gull <i>Creagrus furcatus</i> in Galápagos

Colony-based observations indicate that Swallow-tailed Gulls Creagrus furcatus go to sea only at night. Here, we use GPS tracking technology to reveal the species’ exclusively nocturnal foraging behavior at four colonies in the Galápagos Islands. All nocturnal trips proved to be foraging effort in pelagic waters 19–103 km from nests during breeding. While at sea, individuals spent approximately one-quarter of their time commuting, with half of the time dedicated to area-restricted search behavior. Three years of data from one colony indicate spatial fidelity to a general foraging area. Our research directly confirms that Swallow-tailed Gulls are the only obligate nocturnal foragers among Laridae and contributes to our understanding of nocturnal foraging strategies in tropical seabirds.