by Jana Woerner
My name is Jana Woerner and I’m here to tell you all about the exciting field season that the hyena team recently (aka 8 months ago) had with the Mara Hyena Project in the beautiful Mara Triangle, Kenya.
We are currently working on a large-scale research project to understand how communication drives coordination and decision-making in animal societies. As part of our project, we collared all hyenas older than 20 months in South Clan, one of the social groups that the Hyena Project studies. These collars recorded the GPS locations, activity levels, and vocalizations of every hyena for ~3 weeks.
Spotted hyenas live in complex fission-fusion groups with stable dominance hierarchies. The fission-fusion dynamics of hyena society allow individuals to avoid competition at carcasses without sacrificing the benefits of group defense against neighboring hyenas and other competitors. We want to see how their vocalizations function to recruit clan-mates for group hunts and defense against lions and neighboring hyena clans.
The matriarch of South Clan the day after her new collar was applied.
For those of you who are new to the world of spotted hyenas, feel free to check out the Mara Hyena Project blog to learn more: https://msuhyenas.blogspot.com/
We have an intricate system for naming all individual hyenas, but for now, all you need to know is that any 3-4 letter capitalized name is referring to one of the study hyenas. You can learn more about each hyena here: https://msuhyenas.blogspot.com/2022/10/welcome-to-mara-hyena-projects-south.html
Though it is impossible to detail every single thing that happened during our 5 months in Kenya, I wanted to share some of the highlights from our big collaring experiment.
September 15th, 2022
We officially finished getting Serena Camp, our home base, ready for everyone. Serena Camp is usually home to 1-3 researchers and 3 Kenyan staff members who support our work. However, during the collaring experiment, we had as many as 10 people in camp at a time, so some upgrades had to be made: more tents, more rainwater collection barrels, and more solar panels!
Celebrating the end of a hard day’s work in Serena Camp.
October 4th, 2022
Today we collared our first hyenas. That’s right, hyenas with an “S”! We managed to get two this morning: JOJO and HONR. Collaring every single hyena within the same social group is a big undertaking, and we weren’t sure how long it would take us. We only dart an animal if the conditions are right (i.e. no nearby water, no other predators, ideally situated in short grass so we can easily see the animal) to minimize risk to the animal. This is easier said than done: the territory that South Clan inhabits features lots of tall grass, rocks, and small streams. The tall grass also provides perfect cover and can make locating hyenas very difficult. Needless to say, collaring two hyenas on the first day was a huge achievement!
Small bonus: later this evening, I was able to track JOJO using her fancy new collar and found her on a natal den with her first litter of cubs. :) Can you see the tiny black head sticking out of the den hole?
October 19th, 2022
Things are slowing down after an exciting start – we managed to deploy 13 out of 25 collars in the first two weeks! At this point, most of the hyenas we encounter are either wearing a collar already or too young to be collared. We decide to take a short break from the collaring effort to replenish our food supplies. While Kay and Dee are busy shopping and running other errands in Nairobi, Ari and I hold down the fort in the field. We continue to look for uncollared hyenas in South Clan and visit the other two study clans that the Hyena Project follows. Most importantly, we create a new track that will allow us to easily cross into the western side of South Clan territory without having to take an hour-long detour every time. This takes the better part of two afternoons as we scout potential crossing points across a steep lugga and move giant rocks to clear a path. A couple of days after creating this beautiful track, the hyenas decide that they no longer want to spend any time in the western part of their territory, and we no longer need the track – typical!
Do we want a super stylish tracking collar that everyone else is wearing? No thanks! We’re too small :)
October 31st, 2022
Happy Halloween! And what a special holiday it was! After a week of almost no captures, we deployed collars on both PALA and DETH today. DETH is one of the lowest-ranking hyenas in South Clan and tends to hang out by herself on the outskirts of the territory. Even after almost an entire month of driving around the territory for ~6 hours a day, we hadn’t seen her… until I found her sleeping smack-dab in the middle of the territory this evening. After collaring PALA this morning, none of us were expecting to get lucky again tonight: Marsden was relaxing at the lodge with some friends, David was collecting data in a different clan, and Kay and Dee were busy working in camp… in other words, we were not prepared for this once-in-a-lifetime (well, at least once-in-a-month) opportunity. After several frantic WhatsApp calls between Kay and I, David and I, Kay and David, Marsden and Kay, Kay and I again, we were able to gather the required equipment and collar DETH successfully – communication and coordination of collective behavior at its finest.
DETH with her collar. Her unique ear damage makes her easy to recognize.
December 6th, 2022
We did it! Today we collared GYRO, our final hyena! It only took 64 days, countless hours of searching South Clan territory, and a ton of luck. Collaring the last few hyenas proved incredibly challenging and there were several moments where we almost gave up, but luckily our perseverance paid off. We celebrate by immediately leaving the field to restock on supplies, watch a couple of World Cup games in Nairobi, and spend the holidays with our friends and family.
GYRO practicing how to be a mother with her younger siblings. Cubs belong inside the den, right?
January 1st, 2023
The moment we have all been waiting for is finally here: at exactly 17:00, the collars turn on and start recording audio, fine-scale GPS, and accelerometer data for each hyena. While these collars technically allow us to remotely monitor the entire clan around the clock, Eli, Kayla, and I are back in the field to record videos of the hyenas, conduct daily prey censuses, and record any other interesting events we observe. This will allow us to ground-truth some of our collar data and create a training dataset for our machine learning algorithms.
Does anybody need video footage of sleeping hyenas? We got plenty!
January 3rd, 2023
After a couple of days of relatively little action, we enter South Clan territory this morning to immediately find 15+ of our study hyenas watching a big lion feeding on a buffalo. Though we always try our best to piece together the whole story while we are in the field, this perfectly exemplifies the power of our tracking collars. Normally, we would try to determine who killed the buffalo by comparing how bloody everyone is (i.e., if the hyenas are bloody, they likely made the kill, which was then stolen by the lion). However, we can now go back into the collar data and figure out exactly what happened while we were still busy sleeping in our tents. How cool is that?
BLG watching over her cub as he feeds on some of the buffalo remains.
January 15th, 2023
The days start to blend together: wake up, find collared hyenas, film collared hyenas, count prey animals, repeat. Nonetheless, we manage to film some incredible sightings: lions hunting buffalo, the sound of which lures in hyenas from all around the territory; BSCT carrying her new cubs to the communal den; eland chasing HONR; BAKR trying to mate with PALA… all of these will be valuable when analyzing our collar data. Nothing beats this morning though! Due to a severe drought in Kenya, the river levels are lower than ever, a big problem for hippos. This morning, the hyenas led us to a dead hippo in the Mara River. To our surprise, there was also a massive crocodile feeding on the carcass. South Clan hyenas, however, are hard to intimidate, and they soon start coming together to fight the crocodile. Though hyenas often coordinate to fight with lions, this is the first time we have seen them mob a crocodile!
Definitely stick around until the end for this one…
BSCT with one of her new cubs on the way to the communal den.
January 21st, 2023
Our collar batteries start to die and it’s time to start retrieving the collars. These collars have a remote drop-off mechanism so we don’t need to re-dart the hyenas, which should lead to a pretty uneventful retrieval period. As always, the hyenas have other plans: SLVR sends us on a wild goose chase through the bushes, BSCT drops her collar in a deep hole that requires a homemade fishing pole, and SAMI starts eating hers before we eventually retrieve it.
Gone fishin'.
Epilogue: Fall, 2023
The hyenas are up to their usual antics, and we are busy analyzing the collar data. While we are still labeling the accelerometer and audio data, the GPS data has already revealed some interesting events: squabbles with lions, successful group hunts, and even the start of a new life. STRM, an immigrant male, spent most of his time in January with BLG, who gave birth to a new cub ~3.5 months later. The gestation period for hyenas, you ask? Around 110 days (3.61 months)… very suspicious…
A successful group hunt by JLP, MCKY, and STRM, as recorded on our collars.
BLG’s new cub (Picture credit: Maya Michels)
Stay tuned for more updates from our meerkat and coati projects!