Tuesday, August 30, 2016

5 Months, 5 Moments

Time goes by so fast!  As of today, I have been in Kenya for five months, working as a Research Assistant for the Mara Hyena Project.  In these five months, I have learned, seen, and done so much.  This whole experience is too incredible for me to convey properly in words, but I will attempt to describe here just a few cool moments from my past five months in the Mara... one for each month.

April:

On the morning of April 6, I went out on my first ever "obs" (observations) period with the Mara Hyena Project, riding along with Jared and Benson as they collected data on Talek West clan.  There were so many firsts for me that morning...

I saw my first Mara sunrise!
I saw my first wild lion!
I saw my FIRST WILD HYENAS, including an adorable little black cub who was probably seen by human eyes FOR THE FIRST TIME that morning (I later got to name her Aries, after my own astrological sign)!

(NOTE: Sorry, the cuteness was too intense for me to photograph.)

I can't really pick a favorite moment from that morning, because the whole day took on this glowing, magical sheen that was almost surreal.  But one of my favorite moments was meeting a hyena named Meeko, named after the raccoon in the Disney movie Pocahontas.

We were driving along - the closest landmark was Gargoyle Tree - and then suddenly we saw this beautiful, fluffy subadult hyena, looking at us.
We stopped the car, and the hyena came right up to us.  He looked intently in the open window, gazing at us with curiosity and interest.  I looked back at him as he looked into my eyes.  I didn't realize at the time that Meeko was simply a popcorn fiend; sometimes we have to give hyenas lures like popcorn and powdered milk for the sake of our research, and popcorn was what Meeko was after when he was gazing so intently into the car.  In that moment, all I could think about was the strange, fascinating animal looking back at me through those lovely brown eyes, and what incredible stories his life, and the lives of the other hyenas in his clan, must hold.  I wanted to discover more about the life stories of the Talek West hyenas, to learn who they were, what they do, why they do what they do.  The tales behind those beautiful eyes.  And I knew in that moment, This is why I'm here.

May:

One evening in late May, we went out for observations.  The car I was in was intending to focus on doing "cow count", and just record all the livestock we saw along a specific route in the park.  But the Mara had other plans.

On an open plain, we stumbled upon a rare sight: what looked like an all-out war between two groups of hyenas.  Two fronts, by turns chasing and retreating from each other in a deadly dance, their tails bristled, whooping and loping back and forth.  Eventually, one group retreated for good, running off to the west.  Piecing together the identities of the hyenas involved in the incident, we (together with the other project car present at the scene) realized that this battle had happened between members of two different social groups of Talek West: it was members of the "Main DOC" group against members of the "Pond" group, and Main DOC had successfully kept Pond (the retreating group) away from the impala kill Main DOC had been feeding on.  This war/food competition/chain of team vs team aggressions was an exciting and significant moment to witness.  It may provide evidence that Talek West "clan", which we formerly thought was still one big happy family, is now breaking up into separate clans that compete with each other - or else it already has.

June:

I got kissed by a giraffe at the Giraffe Centre in Nairobi.  Enough said!
July:

In July, I saw my first crossing with Erin and Robyn at the Mara River!

It started with a few zebras.

Then there were twelve crocodiles.

Then there was one less baby zebra.

Then a bunch of wildebeests started crossing the river, and chaos broke loose.

It was breathtaking and shocking and terrible and mighty, seeing life's brutality and its stubborn determination to survive playing out before us.  It all happened so fast that it seemed to be over in the blink of an eye, in a single moment.  So many wildebeests getting torn to shreds by the crocodiles, and so many wildebeests pushing through to the other side of the river.  This wasn't a nature documentary.  This was real life, and real death, unfolding before our eyes.  It was horrific and sad, but also inspiring and beautiful.  It was like nothing I've ever seen before, and I don't think I will ever see anything quite like it again.  

August:

I was sitting on my front porch (well, technically, I was sitting on a chair on the tarp in front of my tent... it's a porch, all right?!) one mid-August morning, talking to my mom on the phone, when I saw some distant branches rustling, and heard some crashing sounds.  I oriented to the noise, but was not particularly alarmed; a few vervet monkeys and baboons pass through our camp and make a racket in the trees, and while vervets are mischievous (raiding tents, stealing food) and baboons can be really destructive (TEARING HOLES IN TENTS to raid them and steal food), this still seemed like business as usual.  See some pesky primates, chase them away.  Camp life, like normal.  If they started moving toward the kitchen, I'd be concerned, so I kept an eye on the area, but I just kept talking to my mom.

The crashing grew gradually louder, and while I tried to keep paying attention to my conversation with my mom, eventually all my senses were geared toward the noise.  As I watched, an elephant appeared out of the thicket on the path right by our camp shower, and was grazing in an easygoing way on the trees around the shower, maybe 50 meters away from me.

For a moment, I was speechless.

"Sorry, Mom," I finally said.  "I've got to go.  There's an elephant in camp and it's about to step on the shower."

"Oh, really?" Mom gasped with a tone of childlike wonder and excitement.

"Yes!" I said, now frantic and worried.  "I have to go.  I love you.  Bye!"

Cautiously, I walked away down the path to the kitchen, my eyes never leaving the magnificent (and terrifying) animal before me until the thicket of trees between us swallowed him.  I told the guys about the elephant, and for our safety, they worked together to chase him away from camp.  They named him "Bubu", which means "mute person" in Swahili, because he had found his way into our camp by making so little noise that no one had heard him coming.  It's incredible, the way such powerful animals can walk so softly, the way such large creatures can vanish into a clump of bushes.

I will never forget that moment: just sitting there, looking into the trees, and then watching an elephant emerge out of nowhere right before my eyes.
~*~
Being an RA for the project has brought such unforgettable moments into my life: the ones I mention above, and so many more.  Here's to the next 7 months, and the road ahead!

Friday, August 26, 2016

A mating like no other and why it matters

Note: This blog contains footage of a mating which recently occurred within Talek West. It is used with the permission of the Mara Hyena Project and for scientific purposes only.

If there is one quality about the Mara ecosystem which can be assured, it is the capacity of the park and its inhabitants to remain unpredictable. A few evenings ago, my fellow RA Amy and I were lucky enough to witness our first hyena mating. This occurrence is rare enough in itself, because hyenas often prefer this to be a more private affair. But what made the session especially interesting from an ecological and behavioral perspective was its participants – Decimeter, one of the most highly ranked females in the clan, and Penne, a natal male.

Penne and his brother Ziti have been special cases within our clan. While most males born within the clan (termed “natal males”) begin to disperse as early as age 2, these brothers have been living comfortably in Talek West for more than 6 years and are showing no signs of wanting to leave any time soon. We fixed both of the boys with GPS collars about 3 years ago when they originally began making long scouting forays into nearby territories, a behavior usually indicating imminent dispersal. However, ultimately not one but both brothers have, at least for the immediate time period, decided that Talek West will remain their home. Now, from what we can deduce from our daily observations, the pair spends the majority of their time hanging out with the high ranking females of the recently split off Main DOC group.
ZITI showing off his GPS collar, which will be used to track him if he disperses
For those unfamiliar with dispersal behavior, especially as it occurs in spotted hyenas, it is a phenomenon which is observed in the vast majority of male hyenas (and indeed in many other males of group-living mammals). Dispersal behavior likely evolved both to prevent inbreeding of closely related individuals and to ensure that the male in question breeds in the clan which gives him the best selection of females which are likely to breed with him. Another important factor which the male must consider when scouting for new clans is the resources which he is likely to gain access to, conditional on the hierarchical climate of the females and males (both natal and immigrant) currently within the clan. Ultimately, he will make his choice based upon the best possible combination of these factors and will gain more and more breeding success in his new clan as he gains seniority over new incoming males.

While it cannot be said for certain what prompted Penne and Ziti to make the unconventional choice to stay, there are certain environmental and social conditions which are fairly rare of the Mara and Talek West itself that could minimize the negative aspects of their decision. Firstly, the park itself, in addition to being one of the prime sites of the migration, is home to a large abundance of other wildlife. In these conditions, carnivores like hyenas, who are extremely versatile in behavior and diet and thus a little less susceptible to human disturbance than species like lions, cheetahs, and leopards, flourish, as even the lowest ranking individuals will likely have regular access to food. However, Talek West is not the only clan living in the Mara, and so even if the clan has an extremely favorable atmosphere in terms of access to food, there are dispersal options which likely have similar conditions as well.
PENE shortly before he was collared
One factor which does play a large role in the success of dispersing males verses natal ones is rank. As natal males, our boys Penne and Ziti are automatically ranked higher than every immigrant male who comes to the clan seeking reproductive success. As such, they have priority access to food and mates over all such males. A study conducted by Davidian et al. on eight separate clans in Tanzania found that, although the number of males which did decide to remain within their natal clan to breed was a small minority, said males had significantly more success with medium to highly ranked females. In their study clans, this led to what was considered equal reproductive success for natal and dispersing males, without the natal males having to dispense the time and energy required to find a new clan.

So if one does consider the role of natal rank not only in its propensity to provide the male with access to higher quality females, but also in its ability to give natal males an additional familiarity with the territory and more time to build good relations with prospective mates, why isn’t this considered to be an optimal breeding strategy in clans which have an equal or higher number of breeding females than their neighbors? Something which must be considered is the willingness of breeding females to take as mating partners males which they have grown up with – in fact, the majority of the time this tends not to happen. This behavior was likely selected for concurrently with that of males to disperse and is one of the key factors which aids in the prevention of inbreeding in what is usually a relatively small clan. But what about clans like Talek West, which while still in the process of fissioning has grown to a size of around 200 individuals? On one hand, this may reduce the possible negative effects of inbreeding. While Penne and Decimeter are both a part of Murphy’s sprawling lineage, dominating nearly half of the clan, there are at least 3 degrees of separation in their relatedness (Penne is the grandson of Decimeter’s cousin once removed to be precise). But of course, there is no way our hyenas could know this to be true. Instead one possibility which could be considered is that, with such a large number of individuals in the clan, the number of regular interactions (and possibly the reluctance of the female to mate) is bound to be reduced.
Decimeter is currently the fifth most highly ranked female in the clan.
While it is still overwhelmingly likely that this natal male will get rejected at the end of the day and find better mating success elsewhere, Penne seems to be doing fine remaining where he is for now. Although we have seen him with at least one high ranking female, it may be impossible to know how many willing breeding partners he and his brother will have in this clan. This may yet lead the boys to disperse to a secondary breeding clan with more willing females. Perhaps we may even see others of his kind arise and find the same kind of success in Talek West – only time will tell.

Footage of the mating between PENE and DECM


Source:

Davidian, E., Courtiol, A., Wachter, B., Hofer, H., & Ho Ner, O. P. (2016). Why do some males choose to breed at home when most other males disperse? Science Advances, 2(3). doi:10.1126/sciadv.1501236

Monday, August 22, 2016

Goin' Courtin'


Just a few days ago, I had the good luck to see one of our North clan males, Leprechaun, engaged in courting behavior with the matriarch of North clan, Waffles.
A flattering photo of Leprechaun, immigrant male.
An even more flattering photo of Waffles, Clan Matriarch.
Courting is an essential part of a male hyena's mating strategy; because mating is entirely female choice in spotted hyenas, the male has to convince the female that he, in particular, is the best male for her to mate with. Male hyenas have many strategies for this, including affiliative behaviors such as grooming and greeting, following a female around constantly (called "shadowing"), defending a female from the approach of other males, and harassing the object of his affection repeatedly.

What we were lucky enough to see was a courting behavior called "bowing", where the male hyena crosses one front leg over the other to indicate his interest in a female. See for yourself!

video

Now, just because we saw Leprechaun making overtures to his beloved Waffles, doesn't mean she is even remotely interested in mating with him. As you could see in the video, she was actually relaxing and nursing her cub while Leprechaun was nervously bowing, and hardly paid any attention to him, except for at the end of the video when she was clearly getting annoyed with his presence and aggressed on him.

Unfortunately for Leprechaun, braving this dangerous situation might not even increase his chances at mating with Waffles in the future – she not being sexually receptive at the time of his courting behavior precludes any real chance on Leprechaun's part for siring her next litter of cubs.

Ultimately, the choice of who to mate with is up to Waffles – Leprechaun just needs to be around when she actually wants to mate, not when she is otherwise occupied with cub-rearing!




Sources: 
    East et al. 2003 Sexual conflict in spotted hyenas. Proc R. Soc. Lond.
    Szykman et al. 2001 Association patterns among male and female spotted hyenas reflect male mate choice. Behav Ecol Sociobiol.50: 231-238.

Monday, August 15, 2016

Self-control matters in spotted hyenas

Hey, it's Lily again. I'm a graduate student out in the field right now collecting cognitive data with the hyenas. One of the cognitive tasks I’m giving hyenas tests self-control, which is also known as “inhibitory control” in many scientific studies. Inhibitory control is the ability to resist a prepotent motor impulse in circumstances that demand restraint. In humans, the “marshmallow test” is a famous self-control test given to small kids. Children are presented with a marshmallow and told that if they can wait fifteen minutes without eating the marshmallow they’ll be rewarded with a second marshmallow. Inhibiting the impulse to eat the marshmallow right in front of them is extremely difficult for many kids and how well kids do on this task is highly predictive of success in life as adults.
The Marshmallow Test 
Inhibitory control is important for other cognitive abilities because it’s thought to be a precursor to more complex thought. Before thinking about how to solve a problem, one must be able to take a step back to assess a situation, i.e. “stop and think”. 

I’m testing inhibitory control in spotted hyenas using a tube task. It’s a standard task for testing inhibitory control in animals and is part of a family of “detour tasks”. Detour tasks test inhibitory control by requiring an animal to initially move away from a food reward before moving towards it to retrieve it. 
 
An example of a detour task conducted with dogs.
This is often done by placing a barrier, like a fence, in front of a clearly visible food reward. In order to get the food, the animal must walk around through a gap in the fence, which requires moving away from the desired food reward. This can be really difficult for many animals who want to run straight towards the food!

A juvenile spotted hyena interacting with the tube task.
The tube task uses a transparent cylinder the rests horizontally on the ground with both ends open. The animal is presented with the tube and they must reach inside either end of the tube without bumping into the side of the tube. Prior to test trials with the clear tube, they are given familiarization trials with a solid tube so that they learn where the openings on the tube are.
An adult female approaches the familiarization tube.
Spotted hyenas are so proving themselves to be quite good at this task, but they occasionally have lapses in their self-control!

SRG fails the tube task.

SRG passes the tube task.

In animals, inhibitory control is related to brain size, dietary breadth, and the degree of fission fusion dynamics. (MacLean et al. 2014; Amici et al. 2008). Amy Fontaine wrote about fission fusion dynamics (FFD) in an earlier blog post here. Animal societies with a high degree of FFD are those like chimpanzee society. Individuals live in large social groups, but most of the time the entire social group does not live together. Instead, they break up into small subgroups of just a few animals and only come together in large groups for specific events. This means that individuals in a social group sometimes go days, weeks, or even months, without seeing some of their group mates. This kind of social living is thought to be cognitively challenging because individuals must remember the identities and social ranks of all their group mates even though they don’t see them that often.

For hyenas, living in a high FFD society is adaptive because it means they can split up to look for food but join together when they need to fight off lions or other hyena clans to defend their territory (Smith et al. 2008). 
Hyenas from Happy Zebra Clan go on a border patrol.
Observing hyenas in the field it’s easy to see that they have great inhibitory control. I’ve seen hyenas patiently wait for hours around a mother giraffe who’d had a still-born calf. They all had the inhibitory control to not mess with the mom, an adult giraffe has a very powerful kick, and instead went to sleep about 30m away from her to wait for her to abandon the still-born calf. In addition, hyenas will wait patiently around a carcass that lions have control of. An adult male lion can kill a hyena with a single swipe of the paw and hyenas have to have the inhibitory control to know just when they can go in and steal food without getting hurt. Out in the Mara, a hyena without inhibitory control will get killed!
A hyena waits for a mother giraffe to leave the still born calf at her feet. 
In addition, spotted hyenas require a lot of inhibitory control in the social domain. Lower ranking hyenas have to inhibit all aggression towards higher rankers, especially when food is present. I’m especially interested in inhibitory control in male hyenas. When hyenas are born, they obtain a social rank directly below their mothers in the hierarchy. Some male hyenas are born as high rankers and some are born as low rankers. However, when male hyenas hit sexual maturity they leave to join a new clan in search of mating opportunities. When a male hyena joins a new clan, he joins at the very bottom of the hierarchy. In their new clans, male hyenas must possess an extraordinary degree of inhibitory control and inhibit all aggression around their new clan mates. Because male hyenas are “destined” to become extremely low ranking when they’re adults and clearly learn to inhibit all social aggression around females and other hyenas in their new clans I think they’ll have much better self-control on the tube task.
A male hyena shows submission by going ears back to an aggressive female. 
The interesting part is, I will also be able to test a prediction of the social brain hypothesis. The social brain hypothesis predicts that big brains are a result of the cognitive demands of living in complex social groups. So far, the social brain hypothesis makes strong predictions in primates and complex sociality does predict complex social cognitive skills, but it’s unclear if social pressures select for cognitive skills outside the social realm. I.e. it’s not clear that complex sociality predicts things like tool-use or spatial navigation. So, just because male hyenas have great inhibitory control in the social realm, it’s not totally clear that they will have great inhibitory control on a physical task like the tube task.  If they do, it means that social inhibitory control also makes male hyenas better at physical inhibitory control!
A hyena plays with the opaque tube.
Amici, F., Aureli, F. & Call, J., 2008. Fission-fusion dynamics, behavioral flexibility, and inhibitory control in primates. Current biology : CB, 18(18), pp.1415–9.
MacLean, E.L. et al., 2014. The evolution of self-control. Proceedings of the National Academy of Sciences of the United States of America, 111(20), pp.E2140–8.
Smith, J.E. et al., 2008. Social and ecological determinants of fission–fusion dynamics in the spotted hyaena. Animal Behaviour, 76(3), pp.619–636.












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