What does a happy toad look like?
By studying animal welfare, or how animals feel, we are in a better position to provide them the care they need. Most zoo animal welfare research has focused on mammals — perhaps because they tend to be cute and have the attention of visitors — yet zoos care for so many other types of animals as well. In fact, mammals make up only 25% percent of animals in zoos and aquariums but are the focus of 75% of the research. So, we’ve got a lot of work to do!
Recently, my research team at Lincoln Park Zoo published a study identifying some some new ways to measure welfare in an amphibian species. It’s a species you may know well from your backyard… the good old American toad. We started out by watching what the toads did to get a sense of what clues they could be giving us about how they feel. This is what we saw:
That’s right. They sit. And they breathe. So, sitting and breathing is what we worked with.
How an animal is breathing can tell us a lot. Animals breathe faster when they are “aroused” or energized, and arousal is one of the two ingredients in animal emotions. The other ingredient is “valence,” which differentiates between good and bad feelings of arousal.
Emotion: Arousal & Valence
Current thinking in emotion research (human and animal) suggests that all emotions can be described by considering how high or low arousal is, and how positive or negative valence is. Feeling “happy” or “playful” would fall in the high arousal and positive valence zone. Feeling “anxious” or “fearful” would fall in the high arousal and negative valence zone.
The “dimensional model” of emotion, characterizing all emotions based on arousal and valence.
Since the rate at which toads’ throats expanded and contracted should reveal how aroused they were, we collected video 24/7 on several toads, and then reviewed the videos in slow motion to document breathing rates. We then started to focus on the other thing we could see, their posture. We created a new “toad posture index” that characterized distinct toad postures based on the angles of their front legs and how much their chest and belly were raised off the ground. Ultimately, we found that toad posture predicted breathing rate!
American toad. Photo by Matthew T Rader on Unsplash.
The cool part - this means someone can tell how aroused a toad is just by looking at how it’s sitting. Part of the reason we found this to be so exciting is because it’s so practical! A zookeeper can literally pass by a tank and start to get a sense of how a toad feels with a quick glance. A big step (hop?) forward for zoo animal welfare.
Next we’ll try to untangle the valence part - is a toad sitting tall feeling “good” arousal or “bad” arousal? We’re also working toward “asking” the toads what features they prefer to have in their habitats. And we’re hoping to find out whether posture can reveal arousal in other amphibian species as well. Stay tuned.
Feel free to leave comments or questions below!
Learn more about the researchers
Sarah Woody, University of Wisconsin, Oshkosh, WI, USA
Rachel Santymire, Lincoln Park Zoo, Chicago, IL, USA
Katherine Cronin, Lincoln Park Zoo, Chicago, IL, USA
Article
Woody, S. M., Santymire, R. M., & Cronin, K. A. (2021). Posture as a Non-Invasive Indicator of Arousal in American Toads (Anaxyrus americanus). Journal of Zoological and Botanical Gardens, 2(1), 1-9. Full article here.
Sources & Notes: Taxonomic representation in zoos extracted from Hosey G., Melfi V., Ward S.J. (2020) Problematic Animals in the Zoo: The Issue of Charismatic Megafauna. In: Angelici F., Rossi L. (eds) Problematic Wildlife II. Springer, Cham. * Dimensional model of emotion developed by Russell, J.A. A Circumplex Model of Affect. J. Pers. Soc. Psychol. 1980, 39, 1161–1178 & Mendl, M.; Burman, O. H. P.; Paul, E. S. An Integrative and Functional Framework for the Study .of Animal Emotion and Mood. Proc. R. Soc. B Biol. Sci. 2010, 277, 2895–2904.
