Passive acoustic monitoring of breeding wedge-tailed shearwaters and black noddies on North West Island, Australia, a viable method for monitoring trends

Background/Question/Methods

The Great Barrier Reef Marine Park (GBRMP) hosts breeding populations of 22 seabird species breeding on over 900 islands.  A review of seabird monitoring data from the Great Barrier Reef Marine Park concluded that existing survey data were insufficient to meet a monitoring goal of detecting a 10% change in seabird populations over a 20-year period.  Given the scale of the GBRMP, the review concluded that managers should adopt new monitoring technologies to help meet these goals. We compared data from passive acoustic surveys to traditional seabird surveys (2 nest counts/season) for wedge-tailed shearwaters (Ardenna pacifica) and black noddies (Anous minutus) on North West Island in the Capricornia Cays National Park, Queensland, Australia, to evaluate the utility of automated acoustic surveys for long term monitoring of these species.

Results/Conclusions

Wedge-tailed Shearwater call rates were significantly correlated with burrow density estimates form traditional counts in 2012/2013 and 2013/2014 (r² = 0.69, p< 0.05 and r² = 0.84, p< 0.05 respectively).  Black Noddy call rates in 2013/2014 are also correlated with nest density estimates from traditional nest counts, but only in the 2 weeks before and after each nest count (r² = 0.6, p< 0.05).  Acoustic activity showed consistent seasonal patterns across breeding sites for both species.  Our results indicate that acoustic monitoring can be an effective tool for monitoring seabirds at the scale required for the GBRMP.