By Kate Ziegler
November 6, 2018
For my project, I am working with Shelby and Danielle to analyze the acoustic activity of humpback whales off the coast of Panama, a popular breeding ground which both northern and southern humpbacks migrate to/ pass through. Humpbacks’ songs are composed of units, phrases, and themes that are repeated in a specific order, and the song is often repeated several times. Many aquatic species utilize acoustic communication for mating, socializing, and predator alerts. However, a large threat to such species is anthropogenic noise, which includes any sound produced by or resulting from human activities. In Panama, anthropogenic noise is especially prevalent from fishing and whale watching vessels which pass through these precious waters.
We are interested to see when these humpbacks are most acoustically active throughout the day and whether anthropogenic noise from passing ships has an effect on acoustic activity. The past two months have been spent cutting audio files and uploading them to Arbimon, an online program where these audio files can be analyzed. Just last week data analysis began and I am so excited!!! We are starting with files from Coiba National Park, a marine protected area. So far I have only gotten through the first day of October, but here is what we are looking for in the files:
All of the dark patches along the bottom of this file are parts of the singer’s song. This audio file was very clear and you can hear the repeats of the various parts of the song. Hopefully if we have enough time at the end of the semester, we can take a file like this and map out the sonic structure. As a side research question, I would be interested to see if the structure of the songs differs between northern and southern humpbacks. Not all files are as clear as this one, which posed a challenge as I sorted through the first day, but hopefully I will become very accustomed to what to look for and the process will get easier and quicker. Interestingly, in a large amount of the recordings there is a low frequency sort of grunting sound, which neither myself nor Dr. May-Collado has yet been able to identify.
by Danielle McAree
6 November 2018
Our research project is centered around the acoustic behavior of male humpback whales (Megaptera novaeangliae), particularly the Southern Pacific humpback whales whose main breeding grounds lie off the coast of Panama. We are investigating the whales’ singing behavior over the course of the day in addition to seasonal patterns, as these whales tend to migrate out of the area starting in late November. We are also focused on the effects of noise pollution on these animals, and are investigating whether differing levels of boat activity impact how and when the whales sing. We are using passive acoustic monitoring data that were recorded by Dr. Laura May-Collado and her colleagues from three sites off the Pacific coast of Panama: Islas Secas, Coiba National Park, and Archipelago Islas Perlas.
At this point, we have finished processing the data files for Islas Secas (one month of recordings) and Coiba National Park (about six months of recordings!), and have started analyzing these recordings in ARBIMON. We are generating a presence-absence matrix in Excel, marking for each recording whether we see (or hear) whales and/or boats, as well as dolphins and fish. Though this process is relatively simple, it is not as easy as I thought it would be. The ocean is a noisy place, and this means that distinguishing one sound from another can get a little complicated. One sound might look like a whale song in Arbimon’s visualizer, but when you listen to it, it might just be a fish or some background noise. This has made the process a little more time-consuming, but it all pays off when I find a whale song or other interesting sounds in a recording. I think this research is very exciting, and it’s fascinating to hear the
Manatees are coastal marine mammals which habitat overlaps with human activities. In Central American and the Caribbean manatee populations have declined due to habitat loss, hunting, and boat collision. Carly’s project aims to use passive acoustic monitoring data to study the acoustic behavior and activity of manatees in Belize. This is not a simple task, as Carly has to comb hours and hours of recordings before finding a manatee call. Her research can help us determine if sound can complement population monitoring efforts in the region. \
My research project is to describe the acoustic repertoire of the Antillean Manatee using over 50 hours of passive acoustic recordings taken throughout 2018 at a resting hole about 6 miles from the coast of Belize. My work is in collaboration with PhD student Eric Angel Ramos, who is studying the behavioral responses of manatees, dolphins, and whales to being observed by drone. In the future, the sounds I’ve selected may be paired with his data to make conclusions about vocal behavior as well as observable physical behavior. What I’m aiming to describe in this project is the vocal parameters of their sounds (min/max/peak frequency, duration, power), unique qualities or “types” of sounds, and the factors (such as time, temperature, season) that affect these qualities or the frequency of the sounds themselves.
But in order to describe manatee sounds, I first had to find them. Identifying manatee sounds was the first real challenge I faced in this research project, as passive acoustic monitoring data is a lot noisier and more confusing that just holding up a microphone to a manatee. On top of having to learn how to use RAVEN, an acoustics program, I had to learn how to recognize and filter through many different types of sounds in order to find my first manatee squeak. After going through ten hours of data in ten second increments, after many hours of just sounds of snapping shrimp, ocean waves, and the occasional fish, I found my first manatee.
Despite my initial challenges, the number of identified manatee sounds has steadily grown over time, so now the time to think about data analysis is rapidly approaching. Very little is known about the possible types of vocalizations made by manatees or what factors affect them. There is not a universally accepted language for describing types of manatee sounds, so much of the data analysis will focus on the vocal parameters themselves, rather than categorizations of sounds and their social contexts, as I had originally hoped to study. It just goes to show that throughout the research process, your question can change to better reflect the data and present scientific context. The thought that I could potentially contribute to this field is both exciting and terrifying. In spite of my fears and challenges, I know the final product will both be valuable as data for the field of marine mammal bioacoustics as well as experience with the research process. While manatees admittedly do not have the most complex social structure or acoustic behavior, this research has opened my eyes to new possibilities of incorporating animal behavior with ecology and conservation actions.