The temporal spacing within flights of Franklin's gulls (Larus pipixcan) was studied. The extent to which gulls formed flocks was related to the time of day and also the apparent destination of the flight. In the morning, gulls departing from a colony toward foraging sites tended not to form flocks if food resources could be located predictably. Where food resources were the least predictable, gulls departing in the morning did form flocks. An intermediate tendency to form flocks occurred for morning departures toward food sources of intermediate predictability. Arriving gulls that fed en route to the colonies had lower temporal clumping than those that flew directly to the colony. Similarly, direct flights of gulls departing toward the evening roost were characterized by high temporal clumping. The highest degree of temporal clumping occurred in flights of gulls between traditional food sites. These findings support the hypothesis that some kinds of flocking in Franklin's gulls are related to increasing the success of foraging individuals. The tendency for flights toward foraging sites whose locations were unpredictable to be somewhat dispersed suggests that flocks of intermediate density provide the greatest benefits during food search.
Orientation and food search behaviour of a deep sea lobster in turbulent versus laminar odour plumes
