The Primates of Zanzibar

While one never gets tired of the majesty they see in the Mara, it can be nice to have a change of scenery. One of the amazing things about East Africa is that one does not need to travel far to experience a whole new ecological world. While the island of Unguja in the Zanzibar archipelago off the coast of Tanzania is a mere 3 hour flight from the Maasai Mara – it’s wildlife makes it seem a world away. Being an island, Unguja is home to many unique animal (and plant) species not found on the mainland. Perhaps some of the most unique species are found in Jozani Chwaka Bay National Park in the center of the island.

            The Jozani Chwaka Bay National Park is a 19 sq mile park on the island of Unguja and is the only national park in Zanzibar. It’s also one of the last strongholds for the endangered Zanzibar Red Colobus monkey. Between 1,600 and 3,000 individuals survive, and despite having Jozani as a stronghold, approximately 50% of the population lives outside of protected areas. The species is also found on Uzi and Vundwe islands in the archipelago. The main threat to these monkeys is habitat loss, but they are also sold in the exotic pet trade and are hunted for their meat.

A mother Zanzibar Red Colobus monkey and her infant. The Jozani primates are very habituated to humans and she continued to nurse her infant despite our presence. 

It’s thought that the monkey has been isolated on the island since the end of the Pleistocene, making it unique from other colobus species found on the mainland. The monkeys’ coloration ranges from dark red to black with a pale underside. While the monkey has a long tail much like that of New World primates, the tail of the Zanzibar Red Colobus is not prehensile and is instead used only for balance. Unlike other primates, the Zanzibar Red Colobus monkeys lack an opposable thumb. To make up for this lack of a digit they have four long fingers on each hand that allow them to clasp firmly to branches as they travel through the forest.  

Another Red Colobus mother and infant. The Zanzibar Red Colobus monkeys are known for their smaller head and hunched body shape - both exhibited well here. 

 The monkey is primarily arboreal and tend to feed on fresh young leaves and are one of the only monkey species to not feed on ripe fruit. However, in agricultural areas the monkeys have been known to spend more time on the ground. Certain populations of red colobus monkeys have been observed feeding on charcoal, which has been shown to be passed on from mother to offspring and may aid in the digestion of exotic plants.

Juvenile Zanzibar Red Colobus playing in the canopy. 

            In addition to Zanzibar Red Colubus, Syke’s monkeys are also found within the national park. While not endangered or vulnerable, the survival of the Syke’s monkey is threatened by habitat destruction and are susceptible to human retaliation due to their tendency to feed on crops or exotic trees. Unlike the Zanzibar Red Colobus, the diet of these monkeys consists mainly of fruits. They have also been observed consuming invertebrates such as slugs and worms. Unlike the Red Colobus Syke’s monkeys exhibit sexual dimorphism with the males being larger than the females.

A Syke's monkey munching on some old leaves and fruit. 

              Being able to walk in the forest and see some of its most charismatic species was definitely one of the most memorable parts of the holiday. Jozani Chwaka Bay National Park was and continues to be a stronghold for both species of primate as well as tree hyrax, bush-baby, dik-dik, and a wide variety of marine species. The park currently partners with the local people in efforts to raise awareness about the forest and its inhabitants to work towards its current and future conservation. 

Brt!!!

In spotted hyenas there is a behavior we call "bristle tail". Bristle tail occurs when a hyena gets excited, and is defined as "having the tail lifted and vertically bristled like a bottlebrush". We often see it in aggressive interactions, but a bristle-tailed hyena is not always on the attack. It also happens to be my favorite behavior to see, especially in cubs! But we'll get to that in a second.

Abid giving a wonderful example of the bristle tail

A fabulous curled variation of bristle tail

When we see this behavior in the hyenas, we make a note of it in the transcription using the abbreviation "brt". So for example we might have:

NANO brt app JLT, eb bo

This means that Nano bristle tail approached Jolteon, who put his ears back and backed off in case Nano's brt meant she was overly excited and going to mess with him. We see brting in all of our hyenas, from our high ranking females to our immigrant males, even all the way down to cubs! And that's the best part. 

Cubs usually bristle tail when there is a particularly good scrap of food worth fighting over at the den, and it's my absolute favorite thing to see.  

Their tails have not quite gotten to bottlebrush quality this early in their development, so often it's just a straight up little toothpick of a tail. Seeing the cubs exhibit these behaviors so young is such a treat, and beyond that fact it just looks adorable! 

It's also a great behavior to exemplify how cubs can boss around hyenas that are older than them! Below you can see Jort bristle tailing while standing up to Magenta, an adult female that is eight years older than Jort!

The cubs of higher ranking females often will aggress on lower rankers, even if the cubs are much younger than the individuals they are aggressing on.

I  hope this post did a good job of introducing you to the wonderful world of bristle-tailing, I love being able to share my favorite behavior!

Til next time! Brt!!!

First impressions of the Mara :)

Hi everyone! I am Erin and I am the newest and last RA to arrive in Kenya of this research year. I’m writing this on my 21^stday in the Mara and am definitely feeling settled and comfortable here at the Serena site. I’m currently here with fellow RA’s Kate and Jess, who have been training me despite all the hecticness that is camp life, and Maggie a grad student who is unfortunately leaving to head back to the States tomorrow. I’m totally blown away by all the Mara has offered me so far and cannot believe that I get to call this amazing place home for the next year. 

A little background on me, I just graduated from Duke University and despite always being a pre-veterinary student, experienced a change in career when I fell in love with the world of ecology halfway through college. Most of my research experience has taken place at the Duke University Marine Lab and in Turkey studying sea turtles and in South Africa’s Kruger National Park. I actually just returned from a short field stint in the rainforests of Indonesia, which only confirmed for me that I needed to get my butt back to Africa. Truly, upon leaving South Africa, I knew I had to get back to the savanna as soon as possible. It is definitely where I like to call home. 

Three weeks in, I’m here to report that I am totally blown away. This project is so much more than I imagined. 

1.    I am amazed at the amount of responsibility is entrusted in the hands of the RAs. From keeping track of money, to helping run grad projects on the ground, and to going back and forth to Nairobi to get supplies, we certainly are not treated as kids out here!

2.    In just three weeks, I’ve learned more about cars than I have in 22 years of life.

3.    Every person I have met is beyond kind and caring.

4.    The food is ridiculously delicious and I have totally fallen in love with chapati and Sukuma…super thanks to our camp staff, Philimon, Moses, and Stephen. 

5.    I love the hyenas way more than I ever thought I possibly would…which is amazing because I am only 3 weeks in and am just beginning to learn their personalities.

A little more insight on number 5. Before coming out here, I didn’t know much about hyenas. Sure, I knew the classic facts such as how they are extremely social, female dominant, and of course, slightly bizarre (or at least to the lay person) because every member has a phallus…male or female. I had no idea how rich their culture would be. I’ve already gotten to see the classic play behaviors, the dominance hierarchy at bay when food is present or during greetings, and have been lucky enough to see some courtship and pre-mating ritual behavior. I’ve also been SO FORTUNATE to see some very teeny tiny black cubs just recently born! The great migration of wildebeest and zebra is in full swing and the hyenas seem to be very fat and happy as a result. 

I’ve also gotten to see lions a fair amount – which has made me grateful to be studying hyenas ha ha – and am loving the bird life that is everywhere I go. Still looking out for cheetah, rhino, and leopards! Though I’m sure those will come.

That’s the short update for now! Keep me in your thoughts as I continue to attempt to learn 180 hyena spot patterns and try to stay out of the ditches and mud puddles of the Mara. Life is busy, but there is nothing else I’d rather be doing. 

The Tawny Jewel of the Savanna

Thomson’s gazelles are probably the Mara’s most underappreciated antelope. They’re small, they’re everywhere, and to most visitors to the Mara they seem relatively mundane. As a result, most tourists tend to drive past Thomson’s gazelles without a second thought. However, there is more than meets the eye when it comes to the overlooked “tommy”.

            The Thomson’s gazelle is one of the most successful species in the antelope family (Estes, 2012), due to its ability to not only graze but also browse on shrubs and bushes when grass becomes scarce. According to Estes, the tommy also has a convertible digestive system that allows it to switch from grazing to browsing (and vice versa) without any difficulty.

            Because of their small size and abundance, tommies are vulnerable to predation from most of the Mara’s carnivores – from eagles to lions. While the tommy can run up to 80 kilometers an hour (compared to 40-60kph for a spotted hyena), it cannot keep this top speed for long. Depending on the danger presented by the predator, tommies alter their avoidance distance. It can be as short as 5 meters for jackals and as long as 1500 meters for endurance predators such as wild dogs and hyenas (Estes, 2012).

            Finally, aside from only needing 1 hour of sleep a day, which alone is rather impressive, my favorite fact about the tommy has to do with its tail. Many of the ungulates in the Mara use their tails to swipe away pesky biting flies, and these motions are usually quick and random. However, upon my first visit to East Africa I noticed that tommies repeatedly swing their tails back and forth on a fairly regular basis – yet few of them were covered in biting flies. After doing some digging, I learned that the wags of the tommy tail are not to keep away flies, but to signal to other tommies. The rump of the tommy is white, which contrasts well against its black tail. The movement of the black tail over the white rump can be seen from some ways away and communicates to other tommies that the wagger of the tail is another tommy (Estes, 2012). This motion is constant and repetitive, much like a dog wagging its tail. This probably helps tommies come together after grazing or may help solo tommies find friendly herds. Because of this, these antelopes have earned the nickname of “savanna puppies” (given to them by yours truly), a special place in my heart, and hopefully now a special place in yours!