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6.3 Understanding the Vocal Behavior
When it comes to studying the vocal behavior of marine mammals, we have a very
important requirement: to have already learned the acoustic repertoire of the species
we are studying. In addition to the vocal repertoire, we need to understand the
behavioral context in which particular acoustic signals are being emitted. Given the
difficulty of conducting experiments on odontocetes in the wild, when our intent
is to understand their vocal behavior, we usually reach the level of correlation
between sounds recorded and behavior displayed. While not the perfect experimental design, at least it allows us to advance in knowledge on these animals.
Alternatively, there have been studies in captivity that allow more controlled
experimentation in odontocetes. However, the caveat is that the behavior observed
in an aquarium is not always representative of what happens in nature. Additionally,
animals may already have long-term effects of years in captivity, which may distort
their displayed behavior and/or vocalizations even more than what we would expect
in the wild. Thus, while we may learn from these experiments, we must be very
careful in the assumptions we make regarding behavioral responses in the wild.
What is the application of understanding the vocal behavior of cetaceans?
Historically we have been relying on visual data to describe their behavior. And this
has its own challenges: to observe the behavior displayed both above the surface and
underwater, to gather information for a long period of time, night time data, or even
adverse weather conditions. These limitations on the visual data speak for the potential need to use complementary data, and acoustic information is one way to overcome some of those challenges. For example, in 2016 Reyes and colleagues
published an article in which they associate certain acoustic signals produced by
Commerson’s dolphins with their displayed behavior. Should they decide to implement some kind of passive acoustic monitoring study in the future for that particular
population of Commerson’s dolphins, they will not only collect information of presence/absence over time, but also gather behavioral information thanks to knowing
in which context particular sounds are produced. This type of data can be extremely
useful when it comes to better understanding habitat use for conservation management, for instance.
In order to understand the vocal behavior, we need to combine acoustic recordings with visual information to study the correlation between particular sounds and
the behavior displayed. For this task a passive acoustic recording system is needed,
such as those introduced earlier. However, the data analysis is less demanding.
Since the repertoire has already been described, most times having them categorized and associated to the behavior displayed by the animals is all we need to
conduct the adequate exploratory or statistical analysis, such as multiple correspondence analysis (Hawkins and Gartside 2009; Reyes Reyes et al. 2016a).
6 Bioacoustic Techniques Applied to Odontocete Conservation and Management…
6.3 Understanding the Vocal Behavior
When it comes to studying the vocal behavior of marine mammals, we have a very
important requirement: to have already learned the acoustic repertoire of the species
we are studying. In addition to the vocal repertoire, we need to understand the
behavioral context in which particular acoustic signals are being emitted. Given the
difficulty of conducting experiments on odontocetes in the wild, when our intent
is to understand their vocal behavior, we usually reach the level of correlation
between sounds recorded and behavior displayed. While not the perfect experimental design, at least it allows us to advance in knowledge on these animals.
Alternatively, there have been studies in captivity that allow more controlled
experimentation in odontocetes. However, the caveat is that the behavior observed
in an aquarium is not always representative of what happens in nature. Additionally,
animals may already have long-term effects of years in captivity, which may distort
their displayed behavior and/or vocalizations even more than what we would expect
in the wild. Thus, while we may learn from these experiments, we must be very
careful in the assumptions we make regarding behavioral responses in the wild.
What is the application of understanding the vocal behavior of cetaceans?
Historically we have been relying on visual data to describe their behavior. And this
has its own challenges: to observe the behavior displayed both above the surface and
underwater, to gather information for a long period of time, night time data, or even
adverse weather conditions. These limitations on the visual data speak for the potential need to use complementary data, and acoustic information is one way to overcome some of those challenges. For example, in 2016 Reyes and colleagues
published an article in which they associate certain acoustic signals produced by
Commerson’s dolphins with their displayed behavior. Should they decide to implement some kind of passive acoustic monitoring study in the future for that particular
population of Commerson’s dolphins, they will not only collect information of presence/absence over time, but also gather behavioral information thanks to knowing
in which context particular sounds are produced. This type of data can be extremely
useful when it comes to better understanding habitat use for conservation management, for instance.
In order to understand the vocal behavior, we need to combine acoustic recordings with visual information to study the correlation between particular sounds and
the behavior displayed. For this task a passive acoustic recording system is needed,
such as those introduced earlier. However, the data analysis is less demanding.
Since the repertoire has already been described, most times having them categorized and associated to the behavior displayed by the animals is all we need to
conduct the adequate exploratory or statistical analysis, such as multiple correspondence analysis (Hawkins and Gartside 2009; Reyes Reyes et al. 2016a).
6 Bioacoustic Techniques Applied to Odontocete Conservation and Management…