Fieldwork Issa (May - July 2017)

On April 24th, 2017, I arrived in Dar es Salaam, Tanzania, for my three-month field season in Issa Valley, Ugalla. I conducted this field period as a part of my PhD study at Bournemouth University in the United Kingdom. My PhD study focusses on chimpanzee landscape use in different environments. It aims to investigate how flexibly chimpanzees can adapt their behaviour to changing landscapes, and how this can be used for chimpanzee conservation and for understanding early hominins (our earliest human ancestors). I am using an individual-based modelling approach based on literature review and field data for this, using a modelling program called NetLogo (Willensky, 1999). Within the models, virtual chimpanzees move around in virtual environments. Environments and individuals follow specific rules based on current literature and field data on chimpanzee behaviour and habitat.

Across equatorial Africa, chimpanzees can be found in various different environments ranging from wet rainforests to dry and marginal savannahs (e.g. Hunt & McGrew, 2002; Inskipp, 2005). Chimpanzees living in dense forests are often called ‘forest chimpanzees’, whereas chimpanzees that live in savannah landscapes are usually called ‘savannah chimpanzees’ (e.g. McGrew et al., 1981; Moore, 1992; Russak, 2013). Compared to the wealth of information that is known on forest chimpanzees, relatively little is known on savannah chimpanzees; to date, their behaviour and ecology has been studied at only a few sites (e.g. Hunt & McGrew, 2002; Pruetz et al., 2002; Russak, 2013). One of these sites is Issa Valley in the Ugalla region of Tanzania (e.g. Stewart & Piel, 2014), and in order to gain more insights into how chimpanzees in marginal savannah landscapes use their environments for their daily needs (e.g. food, water, sleeping locations), I decided to visit this site for my PhD field work period.

Bethan, some of the Issa field assistants, and me. © K. L. van Leeuwen

Issa Valley (or Issa, for short), is a mosaic savannah landscape consisting mainly of (miombo) woodland interspersed by small patches of forest, swamp and grassland (e.g. Hernandez-Aguilar, 2006; Stewart, 2011). The Issa field site is run by the Ugalla Primate Project (UPP), which is led by Dr. Alex Piel and Dr. Fiona Stewart. The UPP has been collecting long-term data on savannah chimpanzee behavioural ecology since 2008, and is currently in the process of habituating the chimpanzees to human presence (e.g. Stewart, 2011). At the moment, it is expected that the Issa chimpanzee community is comprised of at least 67 individuals inhabiting a very large home-range (e.g. Rudicell et al., 2010). Dr. Alex Piel and Dr. Fiona Stewart have been so kind as to share some of their UPP long-term data with me, and this will be very useful for the modelling purposes of my PhD study, determining the exact behaviour and landscapes of the chimpanzees at Issa.

In addition to the long-term UPP data, my three-month field period has mainly focussed on the characteristics of the different vegetation types that can be found at Issa. For the modelling purposes of my study, I wanted to investigate whether different vegetation types (such as forest, woodland, swamp, and grassland) are structurally and climatologically different from each other. I researched this by randomly setting out 24 different ‘vegetation plots’ in different types of vegetation (6 plots in each vegetation type). These plots were 25m x 25m squares in which I measured the characteristics of all trees and vines that had a diameter at breast height (DBH) of greater than 10cm. Tree and vine characteristics included DBH, lowest branch height, tree height, tree species, crown width, canopy cover, canopy connectivity, etc. I also measured some overall plot characteristics, such as total number of trees and vines, tree density, food tree density, altitude, slope, etc. In twelve of my plots, I also set up micro-climate data loggers. These are small pieces of equipment that measure local temperature and light intensity. I set out three data loggers per plot: one at 1m height, one at the highest possible point, and one in the middle of these two. For setting up the data loggers in trees, I used a crossbow-with-fishing-reel system, which was quite an adventure! :) All plots were set up and measured with the help of at least one local field assistant from UPP, who are all very capable of guiding you through the forest and showing you all kinds of interesting things. As you can imagine, these vegetation plots all resulted in lots of data, which I am currently trying to analyse.

Issa landscape. Issa waterfall. Issa landscape.

Doing these vegetation plots gave me the opportunity to visit many different areas across the Issa study site. I was certainly amazed by the diversity (and the beauty) of the landscape. As the UPP is continuously recording their long-term data and many other researchers also visited the Issa study site during my three-month field period, I additionally got the chance to join many other interesting research projects. For example, I got to observe the wild chimpanzees at Issa, I spent a day following the well-habituated baboons, I joined a research team to look at the structural characteristics of nests, I observed red-tailed monkeys; all incredible experiences. On top of that, even more projects are carried out at Issa (such as phenological monitoring, camera traps, and fauna transects), and it has thus been an amazing experience to hear and learn about all these initiatives. As all field assistants working for UPP are local, I also got the opportunity to experience the Tanzanian culture and to learn to speak Swahili (at least for a little bit…). Last, but certainly not least, I got to spent time with many different researches at the Issa field site (from undergraduate students, to PhD candidates, to professors). It has been great to share field-stories with these people and to brainstorm about all our projects.

Issa red-tailed monkey. Issa chimpanzees. Issa baboon.

Halfway through my trip, I got company from my supervisor Ross Hill, my friend and PhD colleague Emma Hankinson, and Bethan Harries and Arron Mallory, two undergraduate students at Bournemouth University. Ross and Emma came to visit for only a couple of days; they helped me with my project and made sure Bethan and Arron settled in camp for their SERT placement study. Bethan and Arron stayed for longer: Bethan joined for 5 weeks and Arron for 3 months. Arron also carried out his own project on the structural characteristics of plots used for nesting in chimpanzees. Both Bethan and Arron have been an enormous help for me in collecting my project’s data, so I’m forever grateful for their help and great company in the field! :)

Arron, Bethan, Ross, me, Emma Arron, Bethan, me, and Ross. Ross, Emma, Arron, and me.

and Jonas. © B. Harries © E. Hankinson © B. Harries

All in all, I can only say that it was truly a wonderful and amazing experience to spent three months in Issa, Tanzania. I will certainly miss this place! Unfortunately, this was the last field season for my PhD study, but I hope to gain many more field experiences in the future! :)

Cheers,

Kelly

* If you have any comments, questions or suggestions, please email me on kvanleeuwen@bournemouth.ac.uk

* For more information on the Ugalla Primate Project, visit http://ugallaprimateproject.com/

References:

- Hernandez-Aguilar, R.A., 2006. Ecology and Nesting Patterns of Chimpanzees (Pan troglodytes) in Issa, Ugalla, Western Tanzania. Thesis (PhD). University of Southern Carolina.

- Hunt, K. D. and McGrew, W. C., 2002. Chimpanzees in the dry habitats of Assirik, Senegal and Semliki Wildlife Reserve, Uganda. In: Boesch, C., Hohmann, G., and Marchant, L., eds. Behavioural Diversity in Chimpanzees and Bonobos. Cambridge: Cambridge University Press, 35–51.

- Inskipp, T., 2005. Chimpanzees (Pan troglodytes). In: Caldecott, J., and Miles, L., eds. World Atlas of Great Apes and their Conservation. London: University of California Press, 53 - 81.

- McGrew, W. C., Baldwin, P. J., Tutin, C. E. G., Assirik, H., and Africa, W., 1981. Chimpanzees in a Hot , Dry and Open Habitat: Mt. Asserik, Senegal, West Africa. Journal of Human Evolution, 10, 227–244.

- Moore, J., 1992. ‘Savanna’ chimpanzees. Topics in Primatology, Vol. I: Human Origins, 99-118

- Pruetz, J.D., Marchant, L.F., Arno, J., and McGrew, W.C., 2002. Survey of savanna chimpanzees (Pan troglodytes verus) in southeastern Sénégal. American Journal of Primatology, 58, 35-43.

- Rudicell, R. S., Piel, A. K., Stewart, F., Moore, D. L., Learn, G. H., Li, Y., Takehisa, J., Pintea, L., Shaw, G. M., Moore, J., Sharp, P. M., and Hahn, B. H., 2011. High prevalence of simian immunodeficiency virus infection in a community of savanna chimpanzees. Journal of Virology, 85 (9), 9918 - 9928.

- Russak, S.M., 2013. Ecological role of dry-habitat chimpanzees (Pan troglodytes schweinfurthii). Thesis (PhD). Arizona State University.

- Stewart, F.A., 2011. The Evolution of Shelter: Ecology and Ethology of Chimpanzee Nest Building. Thesis (PhD). University of Cambridge.

- Stewart, F. A. and Piel, A. K., 2014. Termite fishing by wild chimpanzees: New data from Ugalla, western Tanzania. Primates, 55 (1), 35–40.

- Wilensky, U. (1999). NetLogo. Evanstion, IL: Center for Connected Learning and Computer-Based Modeling, Northwestern University. Available from: http://ccl.northwestern.edu/netlogo/.