Researchers at the University of California, Santa Cruz are developing new acoustic monitoring techniques that could aid seabird conservation.

Abe Borker, a Seabird Biologist, is trying to make population studies of seabirds more cost-effective and efficient.

Borker explains that based on the call of some species of seabirds, you can estimate their population size.

Why acoustic monitoring?

Developments in acoustic monitoring offer conservationists a greater understanding of a population before and after conservation efforts.

In order to count seabirds, researchers often use extensive labor and specialists to locate elusive species hiding on remote portions of islands.

Creating a new method to evaluate the success of invasive species removal projects and can help save threatened seabirds.

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By Emily Heber – 21 july 2017

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A seabird spend much of his time on land hidden in crevices along steep cliffs, which makes it difficult for researchers to gather population data.

Mission Temoe Gambier 226_red© Laurent Yan

Mission Temoe Gambier © Laurent Yan

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The original study


Although wildlife conservation actions have increased globally in number and complexity, the lack of scalable, cost-effective monitoring methods limits adaptive management and the evaluation of conservation efficacy. Automated sensors and computer-aided analyses provide a scalable and increasingly cost-effective tool for conservation monitoring.

A key assumption of automated acoustic monitoring of birds is that measures of acoustic activity at colony sites are correlated with the relative abundance of nesting birds. We tested this assumption for nesting Forster’s terns (Sterna forsteri) in San Francisco Bay for 2 breeding seasons. Sensors recorded ambient sound at 7 colonies that had 15–111 nests in 2009 and 2010. Colonies were spaced at least 250 m apart and ranged from 36 to 2,571 m2. We used spectrogram cross-correlation to automate the detection of tern calls from recordings. We calculated mean seasonal call rate and compared it with mean active nest count at each colony. Acoustic activity explained 71% of the variation in nest abundance between breeding sites and 88% of the change in colony size between years.

These results validate a primary assumption of acoustic indices; that is, for terns, acoustic activity is correlated to relative abundance, a fundamental step toward designing rigorous and scalable acoustic monitoring programs to measure the effectiveness of conservation actions for colonial birds and other acoustically active wildlife.