Like many people around the world, I am working from home. Like many people, I have taken up new “at-home” hobbies like sourdough baking and gardening. And, like so many people, I have brought home a new pet during this uncertain time. Her name is Gouda, like the cheese, and she is an 11-week-old puppy. Gouda is not supposed to go out to parks and public spaces until she has finished her vaccination regimen in order to protect her from contracting Parvo, a potentially fatal virus. Gouda and I have a lot in common right now: we are both staying home, waiting out the chance to safely interact with the world.
When I am not Gouda’s caretaker, I am a PhD student at the University of California, Davis studying animal behavior. Like most people’s plans, research has been put on pause or slowed significantly due to COVID-19. Most of my colleagues’ field seasons have been cancelled. Lab-based research has slowed to a trickle. However, I have plenty of tasks to keep me busy at home. There are data sets to analyze, manuscripts that need edits, and papers to read. However, while I am busy working, there is Gouda, staring at me, sitting by the sink, and whining. What is she trying to tell me? I am learning a lot about animal communication from this small creature that I have welcomed into my home.
When I first adopted Gouda, I set about the task of teaching her how I communicate. I trained her that she should relieve herself outside on the grass. I showed her what items were her toys and which were my slippers (i.e., slippers are not toys). I taught her that when I say “sit,” she sits down. Gouda is chatty, like most puppies she whines when she wants something. She whines when she wants to go outside, when she is hungry, and when she is bored. So why is she whining at the sink?
Turns out, I had not noticed that Gouda’s water bowl was empty. Gouda was telling me that she wanted water by sitting by the sink and vocalizing at me. I was surprised that she knew where the water came from. I was impressed she would try to communicate with me through such a complex signal. She was not just whining to convey overall dissatisfaction; she was trying to tell me something specific. It was then that I realized that by adopting Gouda, I had just created a mixed-species group. As such, we were figuring out modes of sharing information that work for both of us. This does not mean that if Gouda whined at my slipper I would hand it over, but I do have a newfound appreciation for how species have evolved to understand each other’s signals. The world of animal communication is fascinating and wonderful, and you do not need to be in the rainforest to observe that.
Mixed-species groups are incredibly common in nature. Multiple species of birds congregate together on the same tree. Herds of zebras and impala roam across the savannah together. There are amazing examples of monkeys that understand the alarm calls of birds, knowing to hide from a shared predator when hearing the specific scream of a nearby songbird . Researchers, myself included, are fascinated by these cross-species interactions. Why and how do they form? What do they tell us about the evolution of social behavior and animal communication?
There are many hypotheses for why mixed species groups form and what maintains them . Species might share the same predator and thus share vigilance duties by spending time together. Its also might be that those species that share predators hang out together to get “lost in the crowd” and dilute their chances of an attack. Another hypothesis is that these species might compete for the same resource and thus forage together so that one species does not decimate the whole fruit tree before the other finds it. On the other hand, some species might make certain food items easier to access, such that it is beneficial to be nearby them. For example, some species of dolphins flush hundreds of prey fish to the water’s surface in a “ball” while they hunt, causing seabirds and large tuna to forage with them, taking advantage of the congregation of prey caused by the dolphins .
In order to team up, these species must communicate with each other. But, how do they even “share the same language?” Researchers assume that these animals have evolved over time to understand each other’s behaviors: whether intentional or not, species are picking up on this social information . The basic premise is that these animals benefit each other by sharing information about their surroundings, whether it be communicating risk from a nearby predator or the presence of a high-quality food item. The key is that two different species need to be able to effectively receive and understand this shared information. When both species benefit, we might call it an information mutualism.
I know that my mixed human-canine group is different from many mixed-species groups in the wild for many reasons. A primary one is that humans have been selectively breeding dogs for generations. One aspect of this domestication process is that dogs are cued in, more than most animals, to listen to humans. Gouda is not a purebred, but we are pretty confident she is at least in part descended from a hunting dog. That means that her ancestors had been bred to listen to commands and pay careful attention to the tone of human voices so that they could effectively retrieve for their humans. Gouda wants to be around me, and this desire is a trait that we humans have selected for in her. But what strikes me is just how much she actively tries to communicate with me. This is a mutualism, and she benefits my life while I benefit hers. We are a mixed-species group, I am in her pack and she is part of my family.
I hope everyone is staying safe and well, pack and family alike.
Lea Pollack is a fifth year PhD student in the Graduate Group in Ecology. You can find out more about her research on her website. Gouda has not yet made a media presence for herself as she is too busy napping.
 Seyfarth, R., & Cheney, D. (1990). The assessment by vervet monkeys of their own and another species’ alarm calls. Animal Behaviour, 40(4), 754-764.
 Goodale, E., Sridhar, H., Sieving, K. E., Bangal, P., Farine, D. R., Heymann, E. W., … & Muñoz, J. (2020). Mixed company: a framework for understanding the composition and organization of mixed‐species animal groups. Biological Reviews.
 Clua, É., & Grosvalet, F. (2001). Mixed-species feeding aggregation of dolphins, large tunas and seabirds in the Azores. Aquatic Living Resources, 14(1), 11-18.
 Gil, M. A., Hein, A. M., Spiegel, O., Baskett, M. L., & Sih, A. (2018). Social information links individual behavior to population and community dynamics. Trends in ecology & evolution, 33(7), 535-548.
Featured image: My muse. Credit: Michael Culshaw-Maurer
Edited by Allison Lau.