Abstract
Behavioral response studies (BRSs) aim to enhance our understanding of the behavior changes made by animals in response to specific exposure levels of different stimuli, often presented in an increasing dosage. Here, we focus on BRSs that aim to understand behavioral responses of free‐ranging whales and dolphins to manmade acoustic signals (although the methods are applicable more generally). One desired outcome of these studies is dose‐response functions relevant to different species, signals and contexts. We adapted and applied recurrent event survival analysis (Cox proportional hazard models) to data from the 3S BRS project, where multiple behavioral responses of different severities had been observed per experimental exposure and per individual based upon expert scoring. We included species, signal type, exposure number and behavioral state prior to exposure as potential covariates. The best model included all main effect terms, with the exception of exposure number, as well as two interaction terms. The interactions between signal and behavioral state, and between species and behavioral state highlighted that the sensitivity of animals to different signal types (a 6–7 kHz upsweep sonar signal [MFAS] or a 1–2 kHz upsweep sonar signal [LFAS]) depended on their behavioral state (feeding or non‐feeding), and this differed across species. Of the three species included in this analysis (sperm whale [Physeter macrocephalus], killer whale [Orcinus orca] and long‐finned pilot whale [Globicephala melas]), killer whales were consistently the most likely to exhibit behavioral responses to naval sonar exposure. We conclude that recurrent event survival analysis provides an effective framework for fitting dose‐response severity functions to data from behavioral response studies. It can provide outputs that can help government and industry to evaluate the potential impacts of anthropogenic sound production in the ocean.
Highlights
Many marine mammals rely on sound for foraging, maintaining group cohesion, navigation, finding mates and avoiding predators
We found that recurrent event survival analysis (Kleinbaum and Klein 2005) is often used to address questions and data similar to ours
One particular area of expansion of its application has been in plant pathology and it is here that we found the only example of the use of recurrent event survival analysis within ecology (Thomson and Copes 2009)
Summary
Many marine mammals rely on sound for foraging, maintaining group cohesion, navigation, finding mates and avoiding predators. A growing number of these studies have been carried out in recent years on a number of different cetacean species, looking at different acoustic stimuli (Kvadsheim et al 2011, 2012, 2014, Miller et al 2011, Tyack et al 2011, Southall et al 2012, Dunlop et al 2013). Together, these studies are increasing our understanding of species differences in sensitivity to sound, and the importance of context in influencing how individuals respond. The common objective across many of these studies has been to determine the relationship between the dose of a stressor (which can be represented by many different metrics) and response
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
