Classifying cetacean behavior

Clara Bird, Masters Student, OSU Department of Fisheries and Wildlife, Geospatial Ecology of Marine Megafauna Lab

The GEMM lab recently completed its fourth field season studying gray whales along the Oregon coast. The 2019 field season was an especially exciting one, we collected rare footage of several interesting gray whale behaviors including GoPro footage of a gray whale feeding on the seafloor, drone footage of a gray whale breaching, and drone footage of surface feeding (check out our recently released highlight video here). For my master’s thesis, I’ll use the drone footage to analyze gray whale behavior and how it varies across space, time, and individual. But before I ask how behavior is related to other variables, I need to understand how to best classify the behaviors.

How do we collect data on behavior?

One of the most important tools in behavioral ecology is an ‘ethogram’. An ethogram is a list of defined behaviors that the researcher expects to see based on prior knowledge. It is important because it provides a standardized list of behaviors so the data can be properly analyzed. For example, without an ethogram, someone observing human behavior could say that their subject was walking on one occasion, but then say strolling on a different occasion when they actually meant walking. It is important to pre-determine how behaviors will be recorded so that data classification is consistent throughout the study. Table 1 provides a sample from the ethogram I use to analyze gray whale behavior. The specificity of the behaviors depends on how the data is collected.

Table 1. Sample from gray whale ethogram. Based on ethogram from Torres et al. (2018).

In marine mammal ecology, it is challenging to define specific behaviors because from the traditional viewpoint of a boat, we can only see what the individuals are doing at the surface. The most common method of collecting behavioral data is called a ‘focal follow’. In focal follows an individual, or group, is followed for a set period of time and its behavioral state is recorded at set intervals.  For example, a researcher might decide to follow an animal for an hour and record its behavioral state at each minute (Mann 1999). In some studies, they also recorded the location of the whale at each time point. When we use drones our methods are a little different; we collect behavioral data in the form of continuous 15-minute videos of the whale. While we collect data for a shorter amount of time than a typical focal follow, we can analyze the whole video and record what the whale was doing at each second with the added benefit of being able to review the video to ensure accuracy. Additionally, from the drone’s perspective, we can see what the whales are doing below the surface, which can dramatically improve our ability to identify and describe behaviors (Torres et al. 2018).

Categorizing Behaviors

In our ethogram, the behaviors are already categorized into primary states. Primary states are the broadest behavioral states, and in my study, they are foraging, traveling, socializing, and resting. We categorize the specific behaviors we observe in the drone videos into these categories because they are associated with the function of a behavior. While our categorization is based on prior knowledge and critical evaluation, this process can still be somewhat subjective.  Quantitative methods provide an objective interpretation of the behaviors that can confirm our broad categorization and provide insight into relationships between categories.  These methods include path characterization, cluster analysis, and sequence analysis.

Path characterization classifies behaviors using characteristics of their track line, this method is similar to the RST method that fellow GEMM lab graduate student Lisa Hildebrand described in a recent blog. Mayo and Marx (1990) analyzed the paths of surface foraging North Atlantic Right Whales and were able to classify the paths into primary states; they found that the path of a traveling whale was more linear and then paths of foraging or socializing whales that were more convoluted (Fig 1). I plan to analyze the drone GPS track line as a proxy for the whale’s track line to help distinguish between traveling and foraging in the cases where the 15-minute snapshot does not provide enough context.

Figure 1. Figure from Mayo and Marx (1990) showing different track lines symbolized by behavior category.

Cluster analysis looks for natural groupings in behavior. For example, Hastie et al. (2004) used cluster analysis to find that there were four natural groupings of bottlenose dolphin surface behaviors (Fig. 2). I am considering using this method to see if there are natural groupings of behaviors within the foraging primary state that might relate to different prey types or habitat. This process is analogous to breaking human foraging down into sub-categories like fishing or farming by looking for different foraging behaviors that typically occur together.

Figure 2. Figure from Hastie et al. (2004) showing the results of a hierarchical cluster analysis.

Lastly, sequence analysis also looks for groupings of behaviors but, unlike cluster analysis, it also uses the order in which behaviors occur. Slooten (1994) used this method to classify Hector’s dolphin surface behaviors and found that there were five classes of behaviors and certain behaviors connected the different categories (Fig. 3). This method is interesting because if there are certain behaviors that are consistently in the same order then that indicates that the order of events is important. What function does a specific sequence of behaviors provide that the behaviors out of that order do not?

Figure 3. Figure from Slooten (1994) showing the results of sequence analysis.

Think about harvesting fruits and vegetables from a garden: the order of how things are done matters and you might use different methods to harvest different kinds of produce. Without knowing what food was being harvested, these methods could detect that there were different harvesting methods for different fruits or veggies. By then studying when and where the different methods were used and by whom, we could gain insight into the different functions and patterns associated with the different behaviors. We might be able to detect that some methods were always used in certain habitat types or that different methods were consistently used at different times of the year.

Behavior classification methods such as these described provide a more refined and detailed analysis of categories that can then be used to identify patterns of gray whale behaviors. While our ultimate goal is to understand how gray whales will be affected by a changing environment, a comprehensive understanding of their current behavior serves as a baseline for that future study.

References

Burnett, J. D., Lemos, L., Barlow, D., Wing, M. G., Chandler, T., & Torres, L. G. (2019). Estimating morphometric attributes of baleen whales with photogrammetry from small UASs: A case study with blue and gray whales. Marine Mammal Science, 35(1), 108–139. https://doi.org/10.1111/mms.12527

Darling, J. D., Keogh, K. E., & Steeves, T. E. (1998). Gray whale (Eschrichtius robustus) habitat utilization and prey species off Vancouver Island, B.C. Marine Mammal Science, 14(4), 692–720. https://doi.org/10.1111/j.1748-7692.1998.tb00757.x

Hastie, G. D., Wilson, B., Wilson, L. J., Parsons, K. M., & Thompson, P. M. (2004). Functional mechanisms underlying cetacean distribution patterns: Hotspots for bottlenose dolphins are linked to foraging. Marine Biology, 144(2), 397–403. https://doi.org/10.1007/s00227-003-1195-4

Mann, J. (1999). Behavioral sampling methods for cetaceans: A review and critique. Marine Mammal Science, 15(1), 102–122. https://doi.org/10.1111/j.1748-7692.1999.tb00784.x

Slooten, E. (1994). Behavior of Hector’s Dolphin: Classifying Behavior by Sequence Analysis. Journal of Mammalogy, 75(4), 956–964. https://doi.org/10.2307/1382477

Torres, L. G., Nieukirk, S. L., Lemos, L., & Chandler, T. E. (2018). Drone up! Quantifying whale behavior from a new perspective improves observational capacity. Frontiers in Marine Science, 5(SEP). https://doi.org/10.3389/fmars.2018.00319

Mayo, C. A., & Marx, M. K. (1990). Surface foraging behaviour of the North Atlantic right whale, Eubalaena glacialis, and associated zooplankton characteristics. Canadian Journal of Zoology, 68(10), 2214–2220. https://doi.org/10.1139/z90-308

Ocean Jail

a captive marine mammal in an unknown location
Source: Snopes, 2018.

 

By Leila Lemos

PhD candidate, Fisheries and Wildlife Department, OSU

 

This past November, headlines were made when a drone captured images of over 100 dolphins confined in Srednyaya Bay, Russia, for commercial reasons.

Figure 01: Location of the “whale jail” in Srednyaya Bay, near Nakhodka, Russia.
Source: Big Think, 2018.

 

This “whale jail” was installed in Srednyaya Bay to receive “prisoners” last July. The Russian newspaper Novaya Gazeta originally reported the story on 30 October 2018 and stated that 11 killer whales and 90 beluga whales [both actually dolphin species] were being held in captivity. These prisoners represent a record catch for the four companies believed to be responsiblefor the captures: LLC Oceanarium DV, LLC Afalina, LLC Bely Kit and LLC Sochi Dolphinarium.

These 101 black-market dolphins are jammed into tiny offshore pensmade ofnetting and are believed to be illegally up for sale to one of China’s 60 marine parks and aquariums, as told by the British journal The Telegraph. With this entertainment business booming in China and a dozen more venues reportedly under construction, there is a demand for these intelligent, social, wild animals.

Figure 02: Twitter post by the Russian government-controlled news outlet RT showing the tiny pens where the cetaceans are being held in captivity in Srednyaya Bay, Russia.
Source: Snopes, 2018.

 

The full drone footage can be seen here:

https://www.youtube.com/watch?v=SlyD6ox9iSo

 

The prosecutor investigating the case is assessing all documents in order to find out if the animals were captured for scientific or educational purposes, or if they were actually detained with an illegal purpose. Greenpeace Russia and other activists are also closely following the case.

The Novaya Gazetta has also reported that the four companies (LLC Oceanarium DV, LLC Afalina, LLC Bely Kit and LLC Sochi Dolphinarium) that own these containers previously exported 13 killer whales to China between 2013 and 2016. These companies were supposedly granted permission to capture ten killer whales in the wild for educational purposes. However, seven of those killer whales were exported to China. Russian authorities are now investigating this case as a possible fraud.

It is important to remember that in 1982, the International Whaling Commission (IWC) adopted a moratorium on commercial whaling, prohibiting participant countries of this international agreement to capture wild whales, except for a specific set of scientific, educational, and cultural purposes. Currently, the quota for capturing whales varies with purpose, country and species, in accordance with the method adopted by the IWC to avoid negative impact on cetacean populations. However, commercial whaling quota is currently zero (IWC 2019a) and there are now 101 individuals being held in captivity in Srednyaya Bay.

Unfortunately, not all countries participate and engage in this agreement. The map below shows the IWC member countries and when they joined the IWC. Surprisingly, both Russia and China are both IWC members despite their purported activities capturing, holding and selling cetaceans for profit.

Figure 03: IWC member countries and when they joined the IWC.
Source: IWC, 2019b.

 

Also, members can withdraw from the IWC. This past December there was another shocking news regarding Japan’s decision to withdraw from the IWC to recommence commercial whaling for the first time in 30 years (Japan Times 2018). This news has led to concerns that this whale market will further diminish the already declining dolphin populations in the region but may also improve whale populations in the Southern Oceans where Japan has whaled illegally previously (Nature 2019).

 

References:

Big Think 2018. Available at: https://bigthink.com/politics-current-affairs/endangered-whales-black-market-russia?rebelltitem=1#rebelltitem1

IWC 2019a. Available at:https://iwc.int/index.php?cID=html_76#permit

IWC 2019b. Available at:https://iwc.int/members

Japan Times 2018. Available at: https://www.japantimes.co.jp/news/2018/12/20/national/japan-withdraw-international-whaling-commission-bid-resume-commercial-whaling-sources/#.XDT3di3MyfU

Nature 2019. Nature 565, 133 (2019). Available at: https://www.nature.com/articles/d41586-019-00076-2 

Snopes 2018. Available at: https://www.snopes.com/fact-check/whales-in-jails/