12 Dec 2014

Bioacoustics Journal Club

Journal clubs are great ways of keeping up to date with papers in your field. They also serve as a forum for critiques and queries on methods, something that is very helpful when you’re considering similar research yourself. In the fall semester, I organised Bioacoustics Journal Club (BJC). Members of the school of biology and psychology meet once a week to discuss a journal article in someway related to animal communication or bioacoustics. We get quite a range of papers, and I thought I’d share the ones that we covered, along with a brief summary and a few questions that we had about them.

Summary: Looking at vocal communication across animal species, series were not best modelled with Markov chains (looking at probability of a signal given the previous signal) but with a non-Markovian renewal process that allows the signal to be repeated.
Questions: Some of the Levenshtein distances look different from the mean, why did you do a one-tailed analysis? Might larger datasets help to test the robustness of the model? Why did you look at English letters not words?

Summary: Three wren species with different duetting styles, didn’t react differently to playbacks of coordinated, uncoordinated, or alternating duets suggesting that they don’t use duet coordination to assess threat from rivals.
Questions: Would you expect the wrens to react differently to a single individual than a duetting pair? How would you test whether duetting is not important to others but important within pairs?

Summary: Female bonobos loud call more close to the centre of their range to recruit others to feeding patches, whereas males loud call more close to peripheries.
Questions: How do you classify “loud calls”? You mention “female alliances” but how do you define them and what evidence do you have? Would you consider recording vocalisations in future studies?

Summary: Acoustically classified Gorilla close call vocalisations show great individual variability, and mountain gorillas seem to use close calls differently from lowland gorillas.
Questions: How did your spectrograph and cluster analyses work? Could you account for individual variation in the pitch of vocalisations for each individual (as it might reduce the spread?

Summary: Brown thornbills mimic alarm calls from other bird species, appropriate to the type of threat (terrestrial or aerial).
Questions: Could you design a way to elicit alarm calls for a terrestrial threat without playing mobbing calls? Do you know how often the birds had been captured before; could they have become habituated to the capture situation?

Summary: Hens produce distress calls when a low-ranking rooster tries to mate with them, but only if a high-ranking rooster is watching.
Questions: Do you think it’s that there’s a high-ranking male watching, or would any other observer produce the same effect? How does the use of distress calls play out in a normal social setting?

Summary: Bouncing babies or undergraduate students to set beats in an ambiguous rhythm creates accents to that rhythm, so that when they hear accents added to the previously ambiguous rhythm it sounds familiar.
Questions: Why did you choose not to use a rhythm that only used snare for the first beat and high-hat for the following five? Would you expect different (perhaps more pronounced) results?

Summary: Passive monitoring (audio recording) of bats is less expensive than mist-netting and active monitoring; is equally reliable for identifying bat species in an area; and may be useful for monitoring areas where White Nose Syndrome (WNS) is reducing populations.
Questions: How does the audio bat identification software work? Can you use passive monitoring not only to detect presence, but to give a population estimate?

Summary: Three captive killer whales housed for some time with bottlenose dolphins produced more click-chains and whistles in their vocal repertoire than killer whales that hadn’t been housed with dolphins.
Questions: How does vocal repertoire of wild killer whales compare to captive killer whales? Could higher frequency of click-chains and whistles be because of different social environment not addition of new calls to repertoire?

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