Ecological adventures in Kenya

Trinity College Dublin runs an annual tropical ecology and conservation field course to Kenya for students in the School of Natural Sciences. This year, I had the privilege of being the botanist on the trip, which gave me the opportunity to teach an excellent group of students, learn from expert instructors, and see a great deal of Kenya.  I felt pretty special because the other instructors on the course were amazing, from the incredible birders John Rochford and Nicola Marples to the amazing physiological ecologist Colleen Farmer all led by the ecological prowess of Ian Donohue. Of course, Collie Ennis, the amazing herpetologist, was also there (he was on the Late Late Show, you know).

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Figure 1 Lunch at Lake Baringo.

The trip is nine days and it is a fast paced trip around four main sites in Kenya: Lake Nakuru National Park, Lake Baringo National Park, Lake Naivasha, and the Maasai Mara. The trip involves several game drives, where the students have a chance to see the famous African “big five”: lion, leopard, elephant, buffalo, and rhinoceros. It provided incredible opportunities to watch ecological processes in action, including five cheetahs devouring a wildebeest.

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Cheetah having Wildebeest for lunch

But there’s so much more than that… this trip gives the students the opportunity to observe the challenges facing conservation in Kenya: small reserves where the population density of herbivores gets so high that buffaloes sometimes kill lions and where, as a result, the lions have learned to sleep in the trees, invasive plant species filling in where overgrazing leaves open spaces, pollution clogging streams, flooding at all of the Rift Valley Lakes, aridification of agricultural regions, and human-wildlife conflicts.

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Figure 2 Lion sleeping in a tree in Lake Nakuru National Park.

I’m personally fascinated by the reptiles, amphibians, mammals, and birds of Kenya, but as the official botanist on the trip it was my job to try and draw the students’ attention to the less mobile (but no less charismatic!!) flora of Kenya. The flora exhibited incredible variation from site to site, but at each site, invasive species (like Prosopis julifera and Opuntia) were in full force.

I was more interested in the native Kenyan flora. I wanted to find a weird Apocynaceae genus Ceropegia (I did not, alas), but I did find Caralluma acutangula in the same family. This plant is so cool because it is a cactus-like succulent in the milkweed family: a perfect example of convergent evolution.

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Caralluma acutangula

In the Old World, the Euphorbiaceae fill the niche that the Cactacecae fill in the New World. They are incredibly diverse and successful, but probably the most striking of the Euphorbia (to me) is Euphorbia candelabrum. It reminds me of the giant Saguaro cacti iconic of the desert southwest in North America.

Figure 3 Euphorbia candelabrum in Kenya (left) and Saguaro cactus in Arizona, US (right) (human for scale).

Of course, in Kenya you really can’t ignore the Acacia (now Vachellia). I mean you really can’t ignore them, since they are covered in painful thorns. One species in particular, the catclaw acacia or “wait a bit” (Vachellia mellifera), uses backward facing thorns to give you time to pause and think about the plant. Note that similarly thorny plants, with similar nicknames, are found around the world, including Australia’s wait-a-while (aka “lawyer cane”, Calamus australis) and the New World’s “wait-a-bit” (Senegalia greggii). Another case of convergent evolution, as both wait-a-bits are Fabaceae but the Australian “wait-a-while” is in the palm family Arecaceae.

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Figure 4 Bat hanging out on a very spiny Vachellia.

It’s hard to be too angry at Vachellia mellifera, since the honeybees make such a delicious honey out of it! Many of us on the course brought home a few bottles of Kenyan acacia honey made from the nectar of the very tree plucking at our clothing and knocking off our hats.

Because I am fascinated by mutualisms, I was most excited to see the famous whistling thorn acacia (Vachellia drepanolobium) being actively defended by one of its mutualistic ant occupants.

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Figure 5 Mutualistic ant defending its plant host from an herbivore.

The plants of Kenya have many mysteries to explore and fascinate the botanical mind. There are well over 10,000 species of flowering plants in Kenya, though a lack of sufficient research means the real number is unknown. I can’t wait to go back and learn more and if you’re interested in this field course (or really any tropical field course), don’t forget to keep an eye on the plants!

Dr Laura Russo is a post-doctoral Research Fellow in School of Natural Sciences, Trinity College Dublin. The fieldcourse is part of the final year programme for Zoology, Botany/Plant Sciences and Environmental Sciences students on the TR060 Biological and Biomedical Sciences degree programme.

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