Language of Love

Language of Love

Language of Love

15 minute read and listen –
With Valentine’s Day around the corner, we all have love on the brain… at least us humans do. Here at the Preserve the ungulates have already gone through their respective courtship rituals back in the fall. Nonetheless, it seems like a great time to talk about how male ungulates use their voices to attempt to secure reproductive success.

Have you heard the courtship calls of male ungulates at the Preserve? The male elk courtship calls, also known as bugles, are hard to miss. They are a high-pitched whistle that can be heard from kilometers away.1Murie, O.J. 1934. Elk Calls. Journal of Mammalogy, 13(4): 331-336 On the other hand, the male wood bison use soft purring during their courtship dance with females, a sound you have to be very close to hear.2Olson, W.E. 2020. The silent bison: differences in rut vocalizations between breeding age male plains and wood bison. Timbergulch PressWhat causes this variation in courtship sounds? Or, put another way, what are the selective pressures that shape the acoustics of male ungulate courtship calls?

To begin to answer this question, we need to know a little bit about how sound is produced. Figure 1 below and the explanation that follows summarize sound production, and highlight some important acoustic traits that vary across land mammal vocalizations in general.

Figure 1. On left: Elk vocal anatomy including the (A) lungs, (B) vocal folds, (C) vocal tract & (D) nostrils, lips, and tongue. On right: spectrograms of a (a) bear growl, (b) mule deer alarm snort, (c) male mule deer grunt, (d) male plains bison short roar, (e) mule deer fawn cry, (f) coyote howl, (g) elk alarm bark and (h) male elk bugle. The asterisk (*) shows the pitch of the mule deer fawn cry, which typically corresponds to the lowest horizontal line on the graph or the frequency difference between successive harmonics; the arrows (←) point to the harmonics, which, if clear, make a sound tonal. The bracket (}) indicates a lack of harmonics in the atonal mule deer alarm snort. Elk vocal anatomy3Frey, R., & Riede, T. 2013. The anatomy of vocal divergence in North American elk and European red deer. Journal of Morphology, 274: 307-319 drawn by Kelsey Saboraki.

Ungulates and other land mammals produce sounds4Fant, G. 1960. Acoustic Theory of speech production. Mouton, The Hagueusing a combination of their (A) lungs, (B) vocal folds, (C) vocal tract, and (D) their nostrils, lips, and tongue.5Frey, R., & Riede, T. 2013. The anatomy of vocal divergence in North American elk and European red deer. Journal of Morphology, 274: 307-319 Air is forced from the lungs past the vocal folds (A), which vibrate open and closed at a frequency related to their length and tension. Longer, looser vocal folds produce lower-pitched sounds, like the bear growl (a), whereas shorter, tighter vocal folds produce higher-pitched sounds like the mule deer fawn cry (e). Not all sounds an animal makes have a clear pitch. In other words, not all sounds are ‘tonal’. Some sounds are what we call atonal, or noisy, like the mule deer alarm snort (b). The difference is due to whether the vocal folds vibrate rhythmically to create a clear pitch (*), and give rise to clear harmonics (←) or not (}).
After air from the lungs passes through the vocal folds, it encounters the vocal tract (C), which is made of the esophagus, mouth, and nasal cavity. The shape of the vocal tract influences the timbre of a sound, or, a sound’s resonance frequencies. So, while the mule deer fawn cry (e) is close to the same pitch as the coyote howl (f), the resonance frequencies of these two sounds differ. The loudest parts of the mule deer fawn cry are the upper harmonics, while the loudest part of the coyote howl is closest to the pitch itself. You can clearly hear the difference if you listen to the two sounds, and see on the graph that the darkest (a.k.a. loudest) harmonics differ. The tongue, lips, and nostrils (D), as well as the position of the head and neck, can further modify a sound’s resonance frequencies by changing the shape of the vocal tract. The longer and wider the vocal tract is made to be, the lower the resonance frequencies.
The maximum duration or amplitude of a sound may have a lot to do with lung capacity, though similar to the pitch, a range of call durations and amplitudes are possible for a given species. That is, an elk can produce a short alarm bark (g), as well as a long bugle (h). Compare the elk bugle (h) with the mule deer grunt (c) and plains bison short roar (d) to get a sense of how these acoustic traits can vary across male ungulate courtship calls.
We now know how sounds are produced and how acoustic traits can vary across species, but how do these acoustic traits function when it comes to attracting mates? Let’s start by looking at the Theory of Honest Advertisement. This theory suggests that male courtship calls advertise a male’s body size, dominance, or overall fitness,6Reby, D., & McComb, K. 2003. Anatomical constraints generate honesty: acoustic cues to age and weight in the roars of red deer stags. Animal behaviour, 65: 519-530. with the idea being that the largest males are the most dominant and have the greatest success with the ladies.

Elk stag bugles, Yukon Wildlife Preserve.

Acoustically, we can think of this as male courtship calls being low in pitch and having low resonance frequencies, since larger animals should have longer vocal folds and a longer, wider, vocal tract. This is referred to as ‘allometric scaling’ and is the reason baby animals tend to have higher voices compared to adults (see the mule deer fawn cry (e) compared to the mule deer courtship grunt (c) in Figure 1). There is evidence to support the Theory of Honest Advertisement in plains bison. Plains bison courtship calls with lower resonance frequencies are made by males with larger body sizes, and males who have lower resonance frequencies in their courtship calls have greater mating success.7Wyman, M.T., et al. 2012. Acoustic cues to size and quality in the vocalizations of male North American bison, Bison bison. Animal Behaviour: 84: 1381-1391

Mule deer fawn and doe, Yukon Wildlife Preserve

However, conflicting evidence exists for the pitch of male courtship calls. Male elk courtship calls appear to straight up violate the idea of allometric scaling; the courtship calls made by adult male elk actually sound similar or higher in pitch than the cries of newborn elk.8Romanow, C.A. 2014. Designed to attract: the relationship of infant distress vocalizations to other social vocalizations. (Honours Thesis). University of Winnipeg So, while advertising size with low resonance frequencies may be important, there is definitely more to the story. Considering the variation in habitat preferences and in social systems across ungulates species, this shouldn’t be too surprising.

First and foremost, males need to ensure their courtship calls will actually reach the ears of potential mates. That is, we need to consider the venue in which males are making these sounds. If you take your date to a crowded restaurant, you want to be confident they are listening to you and only you when talking about your achievements. Just like ungulates that live in forests, you have to overcome direct physical barriers to your sound reaching your date. In the forest, trees and other vegetation more readily absorb or scatter high-pitched sounds than they do low-pitched sounds,9Marten, K., Quine, D., and Marler, P. 1977. Sound transmission and its significance for animal vocalization: II. Tropical Forest Habitats. Behavioral Ecology and Sociobiology, 2(3): 291-302. meaning high-pitched sounds may not travel very far or very clearly in this type of habitat. We might therefore expect forest-dwelling ungulates to use lower-pitched courtship calls. The low-pitched croaking of male moose is a good example of a forest-dwelling species whose courtship calls fit into this narrative.10Franzmann, A.W. 1981. Mammalian Species: Alces alces. The American Society of Mammalogists, 154: 1-7.

Moose Bull, Yukon Wildlife Preserve

Male ungulates also need to read the room. It would be overkill for your date to yell for your attention while you were having a nice quiet picnic, and the same is probably true for ungulate courtship. Mule deer males use low-amplitude, low-pitched grunting while engaged in a tending bond with a single female.11Geist, V. 1981. Behavior: adaptive strategies in mule deer. In: Mule deer and black-tailed deer of North America. Wallmo, O.C. (ed.). University of Nebraska, Lincoln. Pp 157-224. Contrast this with the literal screaming of a male elk attempting to entice an entire herd of females to stay in close proximity to him, and not to stray toward the lurking satellite males.12Murie, O.J. 1934. Elk Calls. Journal of Mammalogy, 13(4): 331-336 It seems reasonable that the social structure of ungulate species, in particular, their mating system type, would influence the acoustics of male courtship calls as well.

Finally, a discussion of male courtship sounds would not be complete without considering the target audience. We are not always sure if a male courtship call is meant specifically for a female, or whether it is a warning to potential rival males, or somehow a signal that targets both. In some cases, it is fairly clear the sound is meant for females – such as for wood bison males who purr only while engaged in a tending bond with a single female.13Olson, W.E. 2020. The silent bison: differences in rut vocalizations between breeding age male plains and wood bison. Timbergulch PressThe reaction of females or males to a courtship call may also suggest its function. For example, female elk tend to approach or at least alert to the high-pitched courtship calls of male elk.14Murie, O.J. 1934. Elk Calls. Journal of Mammalogy, 13(4): 331-336

It is widely accepted that tonal sounds (such as the mule deer cry (e) in Figure 1) are attractive to other animals, and atonal sounds (such as a mule deer snort (b) in Figure 1) are repelling to other animals.15Morton, E.S. 1977. On the occurrence and significance of motivation-structural rules in some birds and mammal sounds. The American Naturalist, 111(981): 855-869 If courtship calls of a given ungulate species are meant to entice females to approach or stay with a certain male, we might expect them to be tonal. Interestingly, the pitch of infant cries is known to be incredibly attractive to female ungulates,16Lingle, S., & Riede T. 2014. Deer mothers are sensitive to infant distress vocalizations of diverse mammalian species. The American Naturalist, 184(4). DOI: 10.1086/67767717Teichroeb, L.J., Riede, T., Kotrba, R., & Lingle, S. 2013. Fundamental frequency is key to response of female deer to juvenile distress calls. Behavioural Processes, 92: 15-23 so maybe the high pitch of male elk courtship calls grabs a female’s attention the same way an infant cry would.18Lingle, S., Wyman, M.T., Kotrba, R., Teichroeb, L.J., & Romanow, C.A. 2012. What makes a cry a cry? A review of infant distress vocalizations. Current Zoology, 58(5): 698-726.

Male ungulates vary vastly in their approach to attracting females: from the quiet, soft purring of the bison to the loud, high-pitched screaming of the elk, these males have successfully evolved to be heard by and attract respective females. This is pretty impressive given they have to deal with anatomical constraints, consider the environment they are calling in, the number of females they are calling to, and who else is around to hear them. We still don’t have a full understanding of how these different factors have shaped male ungulate courtship calls, and there are even some species we have yet to learn about: mountain goats, thinhorn sheep and woodland caribou to name a few; animals that are tricky to study in the wild.

L to R:  Rebecca making a sound recording of moose at Yukon Wildlife Preserve; Cora making a sound recording of elk at Sandy Hills Elk Ranch.

The focus of my (Cora’s) Master’s thesis is to look at courtship calls from a diverse group of ungulate species that vary in their size, habitat, and mating system type, and to construct models to see which of these factors most readily correlates with the particular acoustic traits that make up the courtship calls. I will also compare the tonality and pitch of a species’ newborn cries with the tonality and pitch of male courtship calls. To do this properly, we require a large data set. Luckily, my good friend and colleague Rebecca Carter is set up with recording equipment that she will use to try and capture some of the courtship calls from ungulates at Yukon Wildlife Preserve. These recordings Rebecca collects will be combined with the elk courtship calls I recorded for my undergraduate thesis, and a library of courtship calls that my supervisor, Dr. Susan Lingle, has amassed through the years as well. I am also scouring the scientific literature for courtship calls of species we do not have access to.

Stay tuned for the results of this research, and remember that size probably isn’t the only thing that matters.

Would you like to contribute to this research? Do you have video or audio recordings of ungulate courtship calls that you’d like to share? We are in need of certain species that are tough to observe in the wild, but welcome the sounds of any ungulate. If you are interested, please email coraanneromanow@gmail.com. Thank you for you interest!

All sound clips credit Lingle Lab:  Dr. Susan
Lingle’s Lab at the University of Winnipeg, with the exception of Grizzly Bear19https://www.nps.gov/yell/learn/photosmultimedia/grizzlysounds.htm and Mule Deer grunt 20https://yukon.ca/en/mule-deer

Cora Romanow & Rebecca Carter

Cora Romanow & Rebecca Carter

Masters Student & YWP Wildlife Interpreter

Cora and Rebecca share a love for wildlife, nature, and sneaking up on and observing deer. They bonded over these shared loves back in Manitoba and on the Alberta grasslands while working in the same behavioural ecology lab, and remain passionate about animals; Cora completing her Masters in animal communication and Rebecca a wildlife interpreter here at the Preserve. Together they strive to make wildlife research accessible and relatable (and at times humorous) to inspire others to also love the natural world.

Kelsey Saboraki

Kelsey Saboraki

Artistic Illustrations - Elk Anatomy Figure

Kelsey Saboraki is a keen observer of the natural world and her scientific illustrations reflect this. Her attention to detail is accompanied by an appreciation for the whole and this balance breathes life into even the most technical of diagrams. For inquiries, contact ksaboraki@gmail.com.

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The Animals are Quite Fine Outside

The Animals are Quite Fine Outside

The Animals are Quite Fine Outside

5 minute read –

After a beautiful, drawn out fall (by Yukon standards), winter arrived in force at the end of October 2020. Record setting snowfall on November 2nd 2020 kicked winter into full gear. Shutdowns were widespread (including here at the Preserve). It was snow joke!

Now that we’ve dug ourselves out, we can offer winter wildlife viewing at its finest! Without leaves on the trees and a beautiful white backdrop, its easier to spot the animals (although the Arctic Foxes can be a bit tricky with their white winter coat). It is especially satisfying to watch animals in their element.

We sometimes get asked if we bring them inside when it gets cold. Apart from the obvious challenges of convincing the Mountain Goats to come down off their cliff, I think they all might get a little hot if they had to be inside. I don’t even want to think about “musk”ox in an enclosed space. And the Bison probably wouldn’t listen to us, even if we asked nicely. Anyway.

They are quite fine outdoors. If you’re not convinced, I give you:

 

Exhibit A: Muskox and Caribou

Muskox and Caribou were wandering around with mammoths on the Beringian steppes during the last ice age. (For better or for worse, the giant beavers didn’t make it). The Preserve’s other ice age animal (and unofficial 13th species) the ground squirrel is much more sensible. They are currently napping right now instead trying to eat each other. While there’s been a lot of snow so far, it’s probably not as much as they had last ice age.

Rebecca spotting deer, in layered clothing to blend into the vegetation - Cora Romanow

Exhibit B: Arctic Foxes.

They also get around the north (quite fine, thank you very much). Incidentally, they may be illegally immigrating into Canada from Norway. This is probably because they are the bomb. By which I mean “Among mammals, the arctic fox has the best insulative fur of all.” In the same paper, they also note that Arctic Foxes don’t start shivering until somewhere below -40c. They’re not quite sure how cold it needs to get, because the scientists that tried, “…did not succeed, because they did not have the necessary equipment available to reach sufficiently low ambient temperatures.”

This Arctic Fox is not only warm, but also enjoying a pumpkin filled with meat treat. No tricks here.

Exhibit C: Mule Deer.

Now stay with me. I realize I’m skipping past a few animals to get to what is arguably the least “winterized” animal at the Preserve. Their large ears and delicate hooves say “I’m new here”. And that’s true – they were first sighted in the Yukon in the 1930s and 40s.

What’s so remarkable about Mule Deer is just how wide a range they now have. Several years ago I was camping in the dessert outside Phoenix, Arizona. And believe it or not, there were Mule Deer wandering around between the prickly pear cactuses! Meanwhile they are now seen as far North as Dawson City, Yukon!! They are simply remarkable animals (Rebecca will back me up on this) that deserve a lot more credit than they get.

And finally,

Exhibit D: Humans

It’s really just us that get hung up about the cold. Last January I had an excellent opportunity to  to make a questionable life choice and strip down to a thin long-sleeve shirt while standing beside a caribou at -35c. I decided to leave my pants on as well as my long underwear not to mention my wool snow pants. Even so, it was quite cold. Painfully cold. Luckily Josh Robertson, a PHD student studying animals with thermal cameras had his camera handy:

The bright yellow bits in the second image are all my heat escaping out into the atmosphere. The caribou is busy eating and clearly doesn’t care. (If you found this foray into thermal imaging unsatisfyingly brief, you’re in luck, we’ve got more on this in the works)!

The animals have got this.

If you haven’t experienced these Yukon species in their element, I highly recommend a trip to the Preserve. If you’re worried about the cold I recommend:

  • Walking (shivering is a metabolic way of warming your core temperature, but walking is a way more effective).
  • Bring some snacks (to fuel your internal furnace).
  • Wear warm clothes (and you know… maybe don’t strip down to pose with animals). Soft soled boots keep your feet flexing and therefore warm. A warm hat keeps the heat from leaking out the top.

I got around a couple days ago and took a few photos to give you a taste of what you’re missing out on! Click for bigger versions – and see if you can find any of the Preserve’s bigger “cats”.

Jake Paleczny

Jake Paleczny

Executive Director

Jake Paleczny is passionate about interpretation and education. He gained his interpretative expertise from a decade of work in Ontario’s provincial parks in addition to a Masters in Museum Studies from the University of Toronto. His interests also extend into the artistic realm, with a Bachelor of Music from the University of Western Ontario and extensive experience in galleries and museums.

867-456-7313
jake@yukonwildlife.ca

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The Antler and Breeding Cycle Featuring Moose

The Antler and Breeding Cycle Featuring Moose

The Antler and Breeding Cycle Featuring Moose

10 minute read –
Deer species are hoofed, ruminant mammals forming the family Cervidae. The primary deer species in the Yukon include: Moose –  the largest of the species; Caribou, Elk and Mule and White-tailed Deer which have migrated in from Alberta and British Columbia over the past 250 years, Mule deer are very well established with their range documented to extend up to the Arctic circle1https://www.britannica.com/animal/mule-deer.

Many of the Preserve’s visitors are fascinated by the antlers, held by members of the cervid family, and ask many questions about them. This article will explain some of the basics on the annual growth and shedding of the antlers and how they play a critical role in the breeding cycle of these animals. We’ll focus on the largest and arguably one of the most Canadian iconic members of the deer family – the moose and his antlers.

Cervids, or members of the Deer Family, grow antlers.  Only males grow antlers, with the exception of Caribou.  Photo left to right:  Caribou, Elk, Mule Deer, Moose.

Let’s begin when last year’s antlers fall off sometime in the mid-winter following the conclusion of the breeding cycle. The antlers separate from the skull at the point of attachment called the pedicel – the base. The antlers – a growth of bone that is chemically altered to fatigue when the animal’s hormones change following the rut, (a term for the breeding season), which also coincides with shorter days and less sunlight. The cast off of the antlers at the pedicle produces an open wound. Like any open wound there is some amount of bleeding, but it does not appear to be a concern for the animal, the blood clots and is washed off by precipitation and a scab like covering develops. 

Antlers separate from the skull at the pedicel, typically in the winter months.

After a couple weeks the new antlers begin to form, and it is not like a tooth where a replacement pushes the old one out of the way in order to grow, it follows a different process. A new antler bud grows in the pedicle of the animal’s skull. Soon after the antler bud has grown for a few days a soft fuzzy fur-like material forms on the bony bud. This is antler velvet and it is an organ. It contains blood vessels, capillaries and nerves that facilitate the growth of the antler over the coming months.

Velvet covers growing antlers:  it contains blood vessels and nerves to facilitate rapid seasonal growth.

While antlers are growing they are engorged with blood and are quite soft and delicate, so much so that the animal is very cautious to not damage their new antlers in any way. If they do become broken or damaged, the animal is stuck with the injured or malformed antler until the next year when a new set will grow after shedding the damaged one later in the present year. A damaged antler may also develop into a ‘non-typical’ antler where it does not match the one on the other side and is often considered a deformity. As an antler bearing animal ages there is a shift in hormone levels, just like humans, and this can manifest in antler deformities or increased ‘non-typical’ tines. As for humans, aging and hormone changes can mean greying hair or more brittle bones. These malformations can spell misfortune for a bull when it comes to successfully fighting off males and attracting females in the rut – we’ll get to that soon!.

Antlers can be damaged during growth; asymmetrical antlers can be the result.  This can spell bad luck for a male when it comes to successfully fighting off males and attracting females.

Antlers grow very quickly. In fact, they are the fastest growing tissue of any mammal. If the animal has a rich and voluminous diet, moose antler growth can mean packing on a pound each day2http://www.adfg.alaska.gov/index.cfm?adfg=wildlifenews.view_article&articles_id=175, in the form of bone of course. Coastal moose in Alaska tend to grow the largest antlers due to the quality and diversity of plants that grow in the temperate coastal areas of their rain forests compared to the colder and less vegetated areas inland like the Yukon. These full sets of antlers are often referred to as a rack.

Moose happily browse the aquatic and terrestrial plants they prefer as their new antlers continue their rapid growth. The high levels of sodium found in aquatic plants help moose antlers to grow quickly. Moose adapt to the additional weight and mass of their antlers and can be very exacting in their use for scratching. They know where each antler tip is and how to control their movements with great precision. One of the most remarkable examples of how well moose can control themselves with a large rack is their ability to walk through a forest and not make a sound as they weave their way through the trees with the equivalent of a kitchen table upside down on their head. They can also scratch delicate parts of their anatomy with an antler tip with little fuss.

Velvet hangs from antlers as bull moose browses aquatic plants in marsh at Yukon Wildlife Preserve.

Over the summer season moose continue to gorge on vegetation as their antlers grow within the velvet encasing them, then a number of changes take place as the autumn season approaches. The first frost and dwindling day light is a turning point and triggers a hormonal change in the animal whereby blood flows back into the animal’s body and stops flowing to the antlers causing the velvet to dry after a few days and become itchy. At the same time bulls that are reproductively mature experience other hormonal changes in anticipation of the rut.

The itchy antler velvet gets rubbed off on trees and the bulls do not look their best as ribbons of bloody velvet hang from their antlers. As they dry, the antlers grow hard due to the process of mineralization and result in a two-type cartilage and bone structure3https://www.msudeer.msstate.edu/growth-cycle.php. The inner portion is less dense, spongy bone that has been highly vascularized during growth. The compact outer shell of the antler is of greater density and is very strong and solid and will become the weapons used when fighting other bulls during the rut which is coming up fast.

Once velvet has shed, antlers calcify becoming strong and solid.  Males are now ready to challenge each other for breeding rights to females.

In preparation for the competition among the bulls (males) to breed a cow (female), the bulls announce themselves by urinating on their bellies or sometimes on the ground and then roll in the mud produced. The purpose of this is to get their scent or pheromones to be carried on the breeze letting the cows know where he is; his readiness to mate and making it easier to be found. Of course other bull moose smell this too and a number of them will gather in a common location on a mountain pasture and their mating fights begin as the bulls gather for the annual main event.

Bears, wolves and other predators also smell the moose pheromones and for them it is like the ringing of a dinner bell and they too gather nearby to take advantage of the situation that will soon unfold.

Elk males, like moose, may announce themselves by urinating on their bellies or sometimes on the ground and then roll in the mud produced

Bull moose stop eating when they go into the rut, partly because of the change in their hormones and also because they don’t have time as they are quite busy chasing other bulls away or fighting with them. Some moose can lose a substantial amount of weight when in the rut rendering them weaker and susceptible to greater injuries. Antlers can do some serious damage to other moose where an eye could be lost, a major organ could be pierced by an antler tip or many other injuries, such as muscle punctures could be sustained that would make it much easier for a grizzly to be successful in it’s hunt for food. That’s why predators hang around the rutting areas, it often results in injured moose bulls that are easier to overtake due to their wounds.

When the cow moose go into estrus or heat, they are only then ready to be bred. Some documentary TV programs elude that it is the bulls’ fighting prowess that determines which bull gets to mate, that may be true but it is not the only consideration. The cow still selects which bull she will mate with and it may be the result of the fights, or the appeal of the bull’s pheromones or other factors we are unaware of. But her goal is to produce the best offspring possible and how she makes that determination is her business. The cow will only breed once, while the bull’s goal is to breed as many cows as he can.

Once all the breeding is concluded, the cows and the bulls go their separate ways and will remain isolated from each other until next year’s breeding season occurs again. During this time, the bull’s antlers fall off and the antler cycle starts all over again.

Cow moose may give birth to a single calf or twins and sometimes triplets in the late spring after the ice and snow have turned to water once again. The bulls wander independently between the low river valleys and the mountain tops browsing while their new antlers grow as they evade predators until the rut calls them back to that special place where the breeding games begin anew.

Doug Caldwell

Doug Caldwell

Wildlife Interpreter

Doug is one of the Interpretive Wildlife Guides here at the Preserve. An avid angler and hunter he has a broad knowledge of Yukon’s wilderness and the creatures that live here. With a focus on the young visitors to the Preserve, Doug takes the extra time to help our guests to better appreciate the many wonders of the animal kingdom here in the Yukon.

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Playful Prey

Playful Prey

Playful Prey

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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The Life of a Mule Deer

The Life of a Mule Deer

The Life of a Mule Deer

7 minute read – 

Watching how an animal behaves in its natural environment and towards other individuals has always been fascinating to me, but I could never have predicted that I would find myself crawling around the open prairie grassland to sneak up on mule deer.  

Mule deer are an indigenous deer species to North America, ranging from as far south as central Mexico up all the way up to Dawson City, Yukon along the western half of the continent. Across their range, mule deer tend to be found in more open habitats along forest edges, in grasslands, and even deserts.  1Sanchez Rojas, G., & Gallina Tessaro, S. (2016). Odocoileus hemionus. The IUCN Red List of Threatened Species: e.T42393A22162113. https://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T42393A22162113.en.

Rebecca spotting deer, in layered clothing to blend into the vegetation - Cora Romanow

A good friend and colleague of mine spent our summer days searching for mule deer fawns to watch how these little animals played and how much of their days consisted of playing.

A mule deer fawn’s life begins around late-May to mid-June, born to a female who is at least two years old. The fawn may be the only off-spring or may have a twin depending on the mom’s health and the amount of food that was available the previous summer.  A newborn fawn has spots on their fur which helps to break up their outline allowing them to hide in long grass. The little fawn will remain close to mom for their first summer, relying on mom’s milk for the first five months before they start to graze on vegetation, then becoming fully independent after a year2 Geist, V. (1981). Behavior: adaptive strategies in mule deer. In O.C. Wallmo (Ed.), Mule and black-tailed deer of North America (pp. 157-224). Lincoln, NE: University of Nebraska. .

For us to watch the deer’s behaviour without influencing them, we needed to be extremely stealthy.

Named for their large ears, mule deer are well suited for living on open and rugged terrain. When detecting a sound, their ears can move independently of one another to allow the deer to hone in on a sound. Their eyes placed on the side of their head allow them to have up to a 310 degree view around themselves.  3Wishart, W. D. (1986). White-tailed deer and mule deer. In Alberta Fish and Game Association (Ed.), Alberta wildlife trophies (pp. 134-143). Edmonton, AB: Alberta Fish and Game Association.

Both of these senses give mule deer an advantage in detecting predators (and us) from far distances, even up to 1km away!   4Lingle, S. (2001). Detection and avoidance of predators in white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus). Ethology, 107, 125-147.   This is especially important in a wide open space where the predators are also able to spot their prey from afar.

We would hike into the prairie with all of the gear we needed – spotting scopes, tripods, a video camera and plenty of paper to document what we saw. We would wear clothing that matched the seasonal grasses (vibrant green in the spring transitioning to browns in the late summer), and layered different colours and patterns to break up our outline, just like the fawns do with their fur patterns.

At times we would make the deer alert to our presence. When alarmed, and especially when they were trying to figure out what type of animal we were, mule deer would stomp one of their front hooves on the ground, move around us to try to get a better view, and make repeated snort vocalizations. The sound of the snort and the stomp, along with releasing an alarm scent from a gland on their hind limbs, functions to alert other deer in the area to potential danger. Females were especially persistent with getting us to show ourselves, which at times we had to scare her away to prevent her from alerting every deer in an area.

Mule deer are generally more stocky and unable to run as fast as say a coyote. Typically, mule deer can reach speeds of 50km/h, but a coyote can run upwards of 70km/h, making it difficult for mule deer to outdistance them. Instead when threatened, mule deer will move on to steeper terrain if available nearby, bunch up together, and confront the predator.  5Lingle, S., Pellis, S., & Wilson, F.W. (2005)  Interspecific variation in antipredator behaviour leads to differential vulnerability of mule deer and white-tailed deer fawns early in life. 6Journal of Animal Ecology, 74(6), 1140-1149.  When a fawn is in danger of being attacked, they will let out a high-pitched distress cry that causes mom to become alert and quickly find her fawn and whoever is attempting to grab them. What’s interesting is that this call will attract all mule deer moms in the area to the fawn regardless of whether the fawn is their own or the fawn of another individual. The females will then group together and perform a coordinated attack using their hooves to kick and stomp at the predator.

Coyote seen looking for preferred prey like deer. A coyote can also camoflauge well into their landscape. 

We never got close enough to elicit this level of antipredator reaction, nor did we want to. We aimed to be quiet and unknown so we could slip in and out of an area without causing undue stress to the animals.

We watched the fawns from when they were born in May, to when they were becoming independent and lanky teens in the late-summer. During this time, we could also see the adult mule deer groups shifting as the seasons changed.

In early spring, pregnant females will stay separate from other deer to give birth in their home range area. Our team can reliably identify deer based on their features, such as markings or scars on the face and/or body, size and shape of the white rump patch, tail length and colouration, and antler size and shape if they are males. Using their distinct features, we could go back into an area year after year and find the same females and her fawns in their homes. The only presence that would really move the deer out of an area would be the grizzly bears and to a lesser extent, coyotes. It seemed to be a dance to figure out week by week where the deer had shifted to if the grizzlies had moved through. After the predators moved on, those same reliable females would take back their homes once more.

As the summer wore on, females and fawns began to come together and spend their time in small groups. There were areas we named “nurseries” where it seemed that the females dropped their fawns together before moving on to graze, apparently taking advantage of the collective antipredator strategy females use.

At the same time, the males were in the bachelor groups or the “dude crews” as we referred to them. They too would be in a consistent area, forming groups of usually 5-10 males of various ages and generally be pretty relaxed looking, staying bedded for the majority of the day. But while they may look lazy, they were really investing a lot of energy into growing their antlers and prepping for the rut (their breeding season).

During the rut, males and females will form larger groups together along with the fawns of that summer and the previous summer’s juveniles. Males fight for access to females who become receptive around the same time in mid-November (although there are some females who are earlier in October and some later into December)2. Into the winter, mule deer of all ages and both sexes stay together in large groups of up to 100 individuals. This is a safety in numbers game to protect them from predators, especially from coyotes whose only available prey are deer since the small rodents such as ground squirrels are hibernating. When spring comes around, the cycle of behaviour patterns continues.

mule deer bucks sparring, rut fall season animal behaviour

Mule deer seem to have an intricate life balancing the ongoing risk of predators, to solving dominance disputes with one another, to looking out for their babies, all influenced by their own individual personalities and the areas they call their homes. Watching animals can give us a new perspective on the animals that live amongst us, and let us know that they are just as complex as us and deserve to have wild spaces left for them to live.

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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Swipe Right (for Antlers)

Swipe Right (for Antlers)

Swipe Right (for Antlers)

Only animals in the deer (or cervid) family grow antlers. That includes elk, deer, moose and caribou.

Animals like Bison, Sheep and Goats are part of a different family and grow horns, not antlers. We’ll tackle that in another video/post!  With the exception of Caribou females, only Cervid males grow antlers, mostly to attract attention from females. 

Antlers are also really important for determining which males will get to breed – this is established through posturing and challenging other males of the same species to duels. 

Antlers grow, and fall off (or shed), every year. Depending on the species and the individual animal, antlers fall off anytime between the end of December to April. This leaves a “kind-of” scar on the animal’s head, called the pedicle – this is the spot where the antler meets the animal’s skull. From that “scar” – or pedicle, the new antler starts to grow – and it is covered in a fuzzy brown skin we call velvet.

 

This photo was captured just moments after the antler shed. The blood is from little bits of dried skin around the pedicle that was attached to the antler. The antler that detached was a pure white bone – no blood. Photo by Jake Paleczny.

The new antlers basically start growing immediately. Within a couple weeks the pedicle will have little fuzzy bumps. Photo by Lindsay Caskenette.

That velvet has nerves and blood supply bringing in nourishment to grow those antlers, which are soft at this point of growth. Antlers grow very quickly and in the Yukon, antler growth is typically done by early to mid-August. Antlers take an ENORMOUS amount of energy to grow. Only the healthiest animals will have impressive antlers.

Once they’re done growing and have fully calcified (or hardened) the blood supply to the velvet stops, the velvet dies and the animal may rub that off on stones/trees or it just falls off.

Because the nerves also die with the velvet, the antlers now have no sensation and are ready to challenge other males to duels, and hopefully impress the females. Antlers can be an important part of asserting dominance.

Female cervids can look at a male’s antlers and have insights in to their diet, nutrition, overall health and of course, genetics. Large, symmetrical antlers say healthy genetics and that means healthy babies.

A female might be impressed – “you grew those antlers in just ONE season?!?” or – she might not be impressed.

Either way, once the breeding season is over, and winter is on its way – hormonal changes triggered by reduced daylight causes the pedicle to begin deteriorating which eventually causes the antler to break away from the weakened pedicle, the antlers will fall off and the cycle renews.

Julie Kerr

Julie Kerr

Visitor Services Coordinator

Julie is a Registered Veterinary Technologist, living and working in Whitehorse since 2012. She joined the team in May 2018. She is passionate about wildlife, nature and living in a conscious manner with both. Her free time is spent outdoors observing wild animals and ecosystems; her connection to the natural world around her brings great joy – joy she loves to share with anyone interested. Honestly? Work and life blend rather seamlessly.

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