Playful Prey

by Rebecca Carter | Aug 28, 2020 | Mule Deer, Research, Thinhorn Sheep | 0 comments

6 minute read –
As many of us know from watching our dogs, cats, or children at home, young animals love to play and they play often. Play behaviour has been observed in many mammals and even in reptiles1Burghardt, G. M. (2015). Play in fishes, frogs and reptiles. Current Biology, 25, 9-10. and octopuses!2Kuba, M. J., Byren, R. A., Meisel, D. V., & Mather, J. A. (2006). When do octopuses play? Effects of repeated testing, object type, age, and food deprivation on object play in Octopus vulgaris. Journal of Comparative Psychology, 120, 184-190.   While you and I can easily imagine what play looks like, researchers still want to learn more about the function play serves in an animal’s life.
Young animals love to play and they play often. Play behaviour has been observed in many mammals and even in reptiles and octopuses!  Seen here at Yukon Wildlife Preserve, lambs of Thinhorn mountain sheep frolic in the spring sunshine.
The majority of play in wild animals occurs when the individual is young, then becoming very infrequent (if occurring at all) in adults. Other behaviours are either expressed throughout an animal’s entire life such as eating, sleeping, and social behaviours, or are expressed at a certain time due to biological constraints, like mating behaviours that only occur when an animal is capable of reproducing. But play itself isn’t constrained by biology, so being concentrated during a particular time makes play an extremely unique behaviour that must have some key role in the animal’s development.
Play also often resembles other behaviours that show up later in life.3Pellis, S. M., & Pellis, V. (2009). The playful brain: venturing to the limits of neuroscience. Oxford, U.K.: Oneworld.  Think about puppies that jump on each other with their mouths open, teeth showing, and playfully going for each other’s necks, or kittens that quietly hunch down and pounce on a toy. These animals are essentially practicing for either settling dominance disputes between pack members or becoming a fierce predator respectively. Play in prey animals like ungulates (hooved animals) often mimics their predator avoidance strategies, which may be giving playful prey an advantage in survival.4 Byers, J. A. (1984). Play in ungulates. In P. K. Smith (Ed.), Play in animals and humans (pp. 5-41). Oxford, U.K.: Basil Blackwell.

Taking what we know about play and what mysteries remain to be revealed in specific species, I looked at the play behaviour in mule deer fawns to see if this pattern of play behaviour mimicking antipredator behaviour held in this species of deer.

To avoid losing fawns to predators in the summer, mule deer females rely on a good defense that often involves a coordinated effort of multiple females. In the winter, both males and females of all ages form large social groups which lowers their individual risk of being attacked. Knowing that mule deer adults are social and rely on being able to communicate with one another especially in stressful situations, the fawns should spend most of their time playing with each other to really build on these social skills, right?

What I love most about nature is that usually our simple assumptions don’t actually hold true.

In comparison with the closely related white-tailed deer, who use their speed and agility to out-run predators and will not defend their young, the fawns of both species played very similarly, instead of matching to their antipredator strategies.5Carter, R. N., Romanow, C. A., Pellis, S. M., & Lingle. S. (2019). Play for Prey: do deer fawns play to develop antipredator tactics or to prepare for the unexpected? Animal Behaviour, 156, 31-40.

So what is happening here?

Thinking back to the timing of play, when this behaviour is most common in an animal’s life is also when the cerebellum (the part of the brain responsible for movement and coordination) is undergoing the most growth and rapidly building connections between cells. This growth is influenced by the animal’s experiences at the time, leading us to believe that play may help with modifying the brain’s development by creating more connections in the cerebellum, increasing the animal’s ability to perform movements.6Byers, J. A., & Walker, C. (1995). Refining the motor training hypothesis for the evolution of play. American Naturalist, 146, 25-40.

The fawns followed the timing trend with the majority of play occurring when the fawns were less than four weeks old, decreasing as the fawns got older despite becoming more active during their days overall.7Carter, R. N., Romanow, C. A., Pellis, S. M., & Lingle. S. (2019). Play for Prey: do deer fawns play to develop antipredator tactics or to prepare for the unexpected? Animal Behaviour, 156, 31-40.

Figure 1. (A) The proportion of active time in which mule deer fawns of different ages played and (B) The average duration of active time for mule deer fawns at different ages.

During play, fawns spent most of their time running, stotting, and rapidly turning around while remaining close to their mom. Running and exploring the area where you are likely spending the most time, may give fawns the opportunity to learn how to navigate their surroundings and be better prepared to escape a predator.

Mule deer fawns also liked to perform chaotic twisty and twitchy movements during play that caused them to stumble around and almost lose their balance (though in a couple of instances the fawns did fall over!). These are what are known as “self-handicapping” movements in play and are thought to help a baby animal learn the limits of their bodies and how to correct themselves when they are close to losing their footing.8Spinka, M., Newberry, R. C., & Bekoff, M. (2001). Mammalian play: Training for the unexpected. Quarterly Review of Biology, 76, 141-168.

Figure 2. Sequence of self-handicapping movements during a fawn’s play.  Play Sketch based off of a video recording of play.

Imagine if a deer was trying to outrun a coyote, and that deer trips on a clump of grass. If that deer had spent time playing in a way that threw them off-balance, then they may have an easier time correcting themselves and continuing on, increasing their chance of survival.

Another part of the brain is involved here and that is the prefrontal cortex. This region is right behind your forehead and is responsible for planning, decision making, regulating emotions, and developing social skills.9Pellis, S. M., Pellis, V. C., & Himmler, B. T. (2014). How play makes for a more adaptable brain: A comparative and neural perspectives. American Journal of Play, 7, 73-98.  Animals who are not given the chance to play show an increased stress and fear response when experiencing a novel situation and have difficulty interacting with other individuals as adults. The prefrontal cortex, like the cerebellum, undergoes a lot of growth and development when an animal is young, overlapping again when animals are the most playful.10van den Berg, C. L., Hol, T., van Ree, J. M., Spruijt, B. M., Everts, H., & Koolhaas, J. M. (1999). Play is indispensable for an adequate development of coping with social challenges in the rat. Developmental Psychobiology, 34, 129-138.

Instead of mule deer fawns playing to develop their specific antipredator strategy (using a coordinated defence against predators), play may more generally improve the fawn’s overall physical and emotional resilience as they grow into adulthood, gaining and refining the skills they need for their survival. The occurrence of play directly impacting survival has been found in grizzly bears,11 Fagen, R., & Fagen, J. (2009). Play behaviour and multi-year juvenile survival in free- ranging brown bears, Ursus arctos. Evolutionary Ecology Research, 11, 1-15. feral horses,12Cameron, E. Z., Linklater, W. L., Stafford, K. J., & Minot, E. O. (2008). Maternal in- vestment results in better foal condition through increased play behaviour in horses. Animal Behaviour, 76, 1511-1518. and mountain goats 13Théoret-Gosselin, R., Hamel, S., & Côté, S. D. (2015). The role of maternal behavior and offspring development in the survival of mountain goat kids. Oecologia, 178, 175-186. with the most playful cubs, foals, and kids being more likely to survive into adulthood.

Mountain Goat kid exploring its habitat at Yukon Wildlife Preserve.   The occurrence of play directly impacting survival has been found in grizzly bears, feral horses, and mountain goats with the most playful cubs, foals, and kids being more likely to survive into adulthood.

Playing by running and jumping around builds up the fawn’s strength, endurance, and coordination – all necessary for a prey animal’s survival. Also adding in those unique self-handicapping movements that twist and disorient the fawn may help to train them both physically and emotionally for dealing with unexpected, stressful situations akin to coming face-to-face with a predator.

Play is such a common and well-known behaviour that we see it every day and could point it out at any given time, yet in terms of its function for different animals, it remains a complex and fascinating behaviour. We think of play as a fun and relaxing activity yet it seems to have a critical impact on an animal’s survival by facilitating the development of crucial motor and cognitive skills.

So next time you are watching your pets play in the backyard or your children roughhousing in the living room, you can think of all the complex brain and motor skill development that is happening as well!

Rebecca Carter

Rebecca Carter

Visitor Services Coordinator

Rebecca joined the Wildlife Preserve in the summer of 2020 after moving from Manitoba to the beautiful and wild Yukon. Rebecca earned a degree in Biology with honours from the University of Winnipeg studying behaviour in mule deer (one of her top 20 favourite animals.. it’s hard to choose!). She loves connecting with others through nature and sharing stories and knowledge about the animals at the preserve with visitors.

867-456-7400
rebecca@yukonwildlife.ca

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