Foraging behaviour of a declining population of Brown Boobies (Sula leucogaster) breeding in the Swain Reefs, Great Barrier Reef

Abstract

The Great Barrier Reef supports significant breeding populations of tropical seabirds; however, recent evidence has indicated declines in seabird populations across some of the most important breeding sites. Evidence for the cause of these significant declines is lacking but is generally thought to result from inadequate food supplies caused by warmer sea surface temperatures associated with climate change. This paper provides the first detailed investigation into the foraging behaviour of Brown Boobies (Sula leucogaster,) a species considered to be more susceptible to climate change impacts due to reduced foraging ranges. Fifteen complete foraging trips were recorded from five individuals (three males, two females). Adults typically foraged in shallow inshore reef waters and the mean foraging trip duration was 6.8 ± 2.8 h with a mean foraging range of 14.5 ± 10.1 km and the total distance travelled being 49.5 ± 30.3 km per trip. While most foraging trips occurred during daylight hours, five (33%) trips recorded periods spent at sea at night. The preliminary results presented here suggest that further research across widely dispersed breeding sites and different species investigating the potential drivers of seabird declines in the Great Barrier Reef is warranted.