Monday, March 31, 2014

Cub demography

Cub pile at South's den.

A major part of a research assistant’s job is keeping up the clan demography. This means keeping track of rank changes and new immigrant males on occasion but mostly means collecting demography information for all the new cubs. Most of the cubs are born around between October and February, but they don't really start to come out of the den until they're one to two months old and they don't get really bold and playful (i. e. start playing underneath the car) until about 3 months. Now that it's March just about every mom has brought her cubs to the communal den of each territory, so we have our hands full! The information we need for each cub includes: who is the mom, if the cub has a sibling, is it subordinate or dominant, what is the cub's sex, and how old is the cub? Additionally, as soon as a cub gets spots we need to get good left and right side photos so we can learn how to ID the cub.

Sport and Citrus investigating the car.

It’s a great excuse to sit at the den and watch cubs play for hours but it can also be very stressful when there are 8 little cubs just starting to get their spots running around and interacting with other hyenas, especially when you have no idea who their moms are. In order to confirm a cub’s mom we have to see it nurse. Sometimes we see this right away and sometimes we have to give a cub a nickname that we’ll use for several weeks until we see it nurse.

Serena's cub board. IRL is short for inter-litter rank, DFS is short for date first seen, and DOB is short for date of birth. 

Yesterday we redid the cub board and removed all the older cubs that were born last year and are no longer living at the communal den. We use this board to keep track of each cub’s information as we collect it. “Citrus” (at the bottom of HZ) is the nickname of the only unIDed cub at Happy Zebra. Since all the mom’s have a specific theme for their cub’s names we can’t give Citrus a real name until we know who his mom is.

This is Higgs-Boson (mom's lineage is subatomic particles) when he was about 4-5 weeks old. At this age they get pale rings around their eyes.

This is Death Star (mom's lineage is space ships) when she was about 7 weeks old. 

Giving a cub a birth date is usually the hardest part. When cubs are between 3 and 9 weeks old aging is usually straightforward based on the amount of white on their face. Between 4 and 5 weeks cubs get pale rings around their eyes which eventually around 5 to 6 weeks turn into white eyebrows. Gradually the white will spread back over their entire face so that at around 11 and 12 weeks their entire head is fairly pale. By 3 months old their black is well on the way out and you can see shoulder spots but the variation at this age starts to broaden.

This is Clever Girl and Shooter (mom's lineage is Jurassic Park quotes) when they were about 3 months old. Notice how the darker fur is just starting to leave their shoulders.

Once a cub starts to get spots the next important thing to do is print photos of it’s spot pattern and learn how to ID her! For each clan we have a book with right and left side photos of every hyena.

Happy Zebra's clan book with ID photos for every hyena. On the front page is the social hierarchy. Offspring are tabbed once underneath their mother.

Right and left spot photos for some of Happy Zebra clan's cubs.

Eleanor nursing her two cubs Hey Jude (in the subordinate position) and Michelle (in the preferred position).

If a mom has two cubs, we also try to identify the dominant and subordinate cub. There are two ways we can do this, the most reliable way is by observing an aggressive interaction between the two cubs and noting which cub was the aggressor and which cub put its ears back and acted submissive. We can also get an idea by which cub is nursing in the preferred position. A mother hyena has only two nipples between her two back legs and all cubs to prefer to nurse parallel to mom, tucked up against her belly. If this position is occupied by the dominant cub the subordinate will nurse between his moms hind legs. This position is less desired because the cub doesn’t get mom’s body heat and can’t be groomed by mom when she’s nursing.

Some cubs, especially smaller ones, often nurse parallel but the cub closer to mom still occupies the "preferred" position. This is Sherman with Astronaut and Rocket Scientist (her lineage is professions).

Cubs also sometimes nurse while their mother is still standing up. We call this nursing "on hoof". This is Teddy Bear nursing from Saur with Gummy Bear off to the right. Saur's lineage is types of bears. 

The next thing we do for a cub, once we know who it is and we can reliably identify it, is try and sex it. Since female hyenas have a pseudo-penis, which we call a phallus, sexing can be difficult. However there are some distinctive morphological differences between male and female phalluses that is detectable even in the cubs. Male phalluses are very pointy, almost spade shaped with a very defined constriction before the head. Female phalluses are either round or blunt at the end and have some to no constriction. These differences can only be seen reliably when the phallus is erect.

This is Blue Band, a female hyena cub.

This is her brother Kachumbari. (Their mom is Clovis, whose lineage is condiments. Blue Band and Kachumbari are both kenyan condiments).

One may think it would be rare to see a hyena cub with an erection but for hyenas the phallus is a tool for social communication. When two hyenas greet each other they typically become erect and will sniff each other’s phalluses. Since all the hyenas love to get to know the new cubs there's usually a lot of social interaction going on at the den and it's not too hard to spot a cub’s phallus. To be on the safe side we always sex a cub three independent times before we can be sure of its sex. On our cub board the black gender symbols indicate the 1st, 2nd, and 3rd sighting. The colored gender symbols indicate a 100% confirmed sex. As you can see we don’t always get it right the first time!

Eremet play-biting Falkor's hind leg (the cub on its back) while Spyro goes for Falkor's ear. (Eremet's cubs are named after dragons).

This is my favorite part of the job because between IDing, aging, and sexing cubs we just get to watch them nurse and play romp!

North cubs debating about whether nor not to go underneath the car.

Sherman's cubs chewing on her radio collar.

UPDATE: Sherman and Hooker both now have really little cubs and don't seem so into fighting Waffles for North's matriarchy. Hence, Waffles is still holding the throne (which some major help from her daughter LogC).

Tuesday, March 25, 2014

Cubs on the Move

Hi! I am the new Serena research assistant. I have been out in the Mara for a bit over a month now. A few days ago when Julie and I were heading back to camp, we came across these three in the middle of the road.  

Sherman was moving her two cubs, Rocket and Astro, from Schiphol Den to DeGaulle Den. As the cubs meandered across the road and snapped at grass stalks, Sherman patiently waited for them and slowly guided her easily distracted cubs towards their new den. The last few meters proved a little too exciting, and Sherman carefully picked up one cub and deposited him in the den hole. When we left, Sherman was curled up nursing Rocket and Astro.

Thursday, March 13, 2014

Hyena talks

Recently we have started giving talks at Mara Serena Safari Lodge on Wednesday nights. This is a great way to teach to the tourists staying at the lodge as well as the employees that work there about hyenas. We spend a lot of time at the lodge (fueling our cars, using their mechanics, getting water etc.) and it feels really good to be able to share some of our work with them and explain why we love hyenas so much and why they are important to study and conserve.

Everyone we have talked to has really enjoyed learning some fun facts about hyenas!

We bring a hyena's skull (left) and a lion's skull (right) to show how their skull morphology differs and how that impacts their bit force! We also show off the hyena's worn down bone crushing teeth. 

So far this has been a really positive experience. We have met a lot of interesting people from around the world and have been able to dispel some very common misconceptions about our favorite social carnivore. Hopefully we are able to continue this

Tuesday, March 11, 2014

Waffles, LCS, and Kruuk's Culvert.

Right now the north hyenas “club” is at Kruuk’s culvert, a culvert just about a kilometer north of camp. We use the word “club” to refer to an area where the hyenas seem to prefer to hang out. The club and the den are the two main centers of activity within a territory. Kruuk was one of the first scientists to study spotted hyenas and is also the one who originally termed the word “club” to mean a spot where the hyenas like to hang out. The fact that the north hyena's club is currently at Kruuk's culvert is entirely coincidental but in the last few days we've seen some interesting stories unfolding here that have to do with our favorite hyena friendship, that of Waffles (North clan's matriarch) and LCS (a very low-ranking hyena in North clan named for her ear damage, a slit in the 'c' area of her left ear). 

LCS and Waffles are best buds. 

Two days ago we followed Waffles, North’s matriarch, to Kruuk’s culvert along with Waffles’ daughter LogC, son Torani, and grandson George. They joined up with Tinsel who was nursing her daughter Rama by Kruuk’s culvert. Not long after all the hyenas had seemed to settle down for the day we heard an antelope dying in the thicket not too far away. Immediately all six hyenas were up on their feet loping towards the source of the noise. We arrived to see LogC and Torani holding two halves of an impala calf- they clearly hadn’t killed it but they’d chased off the hyena who had before we arrived. Back towards Kruuk’s Culvert we saw that LCS had joined the group and we thought it might have been her who killed the calf since she was the only new hyena here. However poor LCS, a very low-ranking hyena, was not welcome at this hang out. LogC and Tinsel, with their blood still up, started aggressing on her the moment she got closer, asserting their higher ranks.

LCS also happens to be Waffles’ best friend but Waffles couldn’t do anything about her daughter’s aggression. In fact, in the heat of the moment Waffles actually joined in on a low level aggression we called a point, in which an animal rigidly points its entire body at the subordinate animal, usually with tails and ears erect. Even though this was a very low level aggression LCS had had enough, and she wasn’t going to forgive Waffles for that mishap. As LCS started to lope away Waffles’ demeanor changed from energetic to confused. We followed Waffles as she went loping after her best friend. When LCS disappeared a few hundred meters ahead of us over a low rise Waffles paused to give out four long low whoops, possibly trying to call her friend back. This was the first time I’d ever seen a hyena whoop in order to specifically call another hyena. Usually whoops seem to be reserved for announcing food or lions. However LCS essentially slammed the door in Waffles face when we crested the rise to see her disappear into a dense patch of grass without a single backwards glance.

LCS and Waflfes sharing a natal den.

Sometimes it really seems like Waffles and LCS’ friendship is a little lopsided with Waffles always pursuing and trying to be friendly to LCS, who can be indifferent. It was Waffles who moved her cubs to LCS’ natal den (where she had given birth to her son WAWA) and though LCS seemed perfectly content to share her hole with Waffles’ she really didn’t have any say in the matter. This goes against what the literature says animals of different ranks should behave. In socially complex animal societies lower ranker animals almost always prefer to associate with higher-ranking animals for benefits that such associations can confer. As a very low-ranking hyena LCS should be the one pursuing friendship with Waffles, the matriarch, rather than the other way around!

LCS and Waffles looking alert while their cubs explore the breakfast plains. 

Yesterday, to our relief, it seemed that Waffles and LCS had reconciled their differences and were back to being friends again. Together they took their cubs for one of their first graduation walks. Their destination? No big surprise: Kruuk’s Culvert. Kruuk’s culvert is a little over a kilometer away and this was the furthest from the den I’ve ever seen cubs of only 4 months old. Mrs. Butterworth (MRSB), Aunt Jemima (ANTJ), and Wailing Wall (WAWA pronounced Way-Wah) were all extremely excited to be out in the world. MRSB, ANTJ, and WAWA are all best buds (all boys) and they happily romped through the tall grass with their heads up and tails bristled.

New best buds in the making. MrsB, Wawa, and AntJ. 
It made me worry a little, if Waffles and LCS had bumped into any trouble there weren’t any holes near by for the cubs to take cover in and Waffles and LCS certainly wouldn’t be able to protect them from lions if it came to that. However, late morning is probably one of the safest times to take your cubs for a walk because the lions will hopefully all be asleep in the warm sunlight.

On their way back from Kruuk’s culvert they detoured a little bit over to Muffin den, the natal den where all three cubs had been raised until they were a little over a month old. I imagine the cubs’ paws must have been extremely sore by that point but they were as bouncy as ever while Waffles and LCS were starting to look a little exhausted. Even if Waffles and LCS’ relationship is a little lopsided LCS clearly still trusts Waffles greatly. She decided to sack out (lay down) in the small water hole near Muffin den to rest while her son WAWA went with Waffles and her cubs back to the den.

Very excited bristle-tailed MrsB and AntJ running through grass. 

Thursday, March 6, 2014

Stillborn giraffes and patient hyenas.

The other day while out on morning observations we saw a giraffe behaving very strangely. We first noticed her from almost a kilometer away, her tall form silhouetted against the rising sun to the east as we drove towards the river in south clan's territory. We thought it was odd to see just one giraffe and it wasn't until we were less than 100m away that we noticed the hyenas. There were 10 adult hyenas all sleeping in a circle around the giraffe. She seemed very distressed but unwilling to leave the ring of hyenas around her and we weren't sure why she didn't just walk off. It wasn't until we were just 25m away that we saw the dead calf at the giraffe's feet. It looked like it had been a stillborn, possibly born the night before. 

It seems that one adult giraffe can be quite formidable to a hyena, or ten. However, I was amazed by our hyenas patience. They knew they couldn't take on the mother giraffe but they were quite content to simply sleep and wait for the mother giraffe to give up on her dead calf. It was touching the way the mother giraffe would lower her head to nudge and sniff at the calf. She was clearly upset about the hyenas presence; it seemed that they made her even more reluctant to leave the calf. Though sad, this calf would provide a free meal for all the hyena moms that were patiently waiting. Four of the ten hyenas there all have little cubs at the den and they need nourishment too. 

We stayed with the giraffe and the hyenas for two hours before it started to get too hot and we left to go back to camp. The next evening there was no sign of the calf at all, since this is the lean time in the Maasai Mara for the hyenas this isn't too surprising. 

Michigan State University | College of Natural Science