Baobabs and bats – new publication on the influence of the landscape and plant traits on fruiting success

Baobab (Adansonia digitata) trees are iconic symbols of the arid lands of continental Africa, and aside from some populations in Southern Africa are largely dependent on fruit bats for pollination. However, the bats visit a diversity of plant species to meet their energetic and nutritional needs, so the pollination service they provide the baobabs may be influenced by the landscape context of individual trees. In collaboration with Dr Paul Webala, Macy Krishnamoorthy set out to determine the relative contribution of individual plant traits, namely tree height and girth, and landscape features and context (e.g., the distance of baobab trees to conspecifics, distances to resources that might attract or distract bats, land use) to baobab reproductive success. Very ably assisted by Mr Michael Bartonjo, she mapped more than 700 baobab trees in ~10 km2 area in Kenya, measured them, and derived a number of landscape variables for each tree. She counted the number of fruit per baobab as a measure of reproductive success.

A mighty baobab with Paul Webala’s magic field bus beneath it for scale

So what did she find? Perhaps not surprisingly, larger trees were more likely to produce fruit and produce more fruit, but landscape variables also played a role, but in a complex and scale-dependent way. The importance of distance to and density of alternate food resources changed with scale, but generally, pawpaws tended to act as attractants whereas figs distracted bats from their role as pollinators.

Eopmorphorus wahlbergi – one of the fruit bat species known to pollinate baobabs

You can read the full story here:

Krishnamoorthy, M.A., Webala, P.W. & Kingston, T. Baobab fruiting is driven by scale-dependent mediation of plant size and landscape features. Landsc Ecol (2022).

Macy in a baobab tree! Baobab trees can live for well over 1000 years and reach up to 5 m in diameter at breast height, so they make for good climbing.

Fieldwork was fun but arduous and there are many people in Kenya to thank! A special thank you to Macy’s local host Daniel Ngei and his family, the local chief Joseph Kavui and all the landowners in the villages of Kaai, Kalesi, Kaluku South, Kandundu, Katithini, Kavui, Kawula, Kiwaani, Mutoleka, Ngieni East, Ngieni West and Yungamaduu who generously allowed us to sample baobabs or others fruiting trees on their lands. Funding for the project came from Bat Conservation Internationa, the Association of Biologists at Texas Tech University, and the Department of Biological Sciences at TTU.

Bats love the baobab flowers, but the fruits are quite a local snack for people. Here they have been dyed green to be sold for $0.05 a bag.

Tigga in Kenya with Dr Paul Webala

Last month I had an excellent trip to Kenya to visit with Dr Paul Webala at Karatina University, which resulted in a Letter of Intent between Texas Tech and Karatina that we hope will facilitate future collaboration and student exchange between our institutes. We then went off to western Kenya in pursuit of bats, starting with the most easterly section of of Africa’s tropical rainforest, preserved in Kakamega Forest. It was beautiful, and we caught some super bats ….

We then started heading towards the Lake Victoria area, but stopped on en route at an Eidolon roost that Beryl will be monitoring as part of a continent-wide initiative, and building on Paul’s work on colonies in this area that was supported for several years by Rufford. 

We stayed at the Impala Sanctuary just outside Kisumu, on the shores of Lake Victoria, where we had a highly productive time catching and recording edge/gap bats.

We had enough time for a trip to one of the fishing villages on the Lake’s shores — very exciting for me as I teach about the catastrophic biodiversity collapse precipitated by the introduction of the Nile perch and Tilapia in both my Ecology and Conservation Biology classes.

 

I had a wonderful time and would like to thank Paul for being such an awesome host, and was very excited to work with Beryl, Mike and Simon (great bat futures ahead of you all). Thanks to Texas Tech (Department of Biological Sciences, College of Arts and Sciences, and the Vice President for Research’s Office) for funding the trip. I’m sure great things will come of it.