[en] Abstract : Damage to crops is a major cause of human–elephant conflict (HEC) in elephant range states. Elephant crop raiding drives farmers' resentment against elephants and reduces local community support for wildlife conservation. While elephant crop raiding ecology is well studied, further investigations on HEC mitigation strategies are still needed. Thus, there is a need to focus on less investigated areas, such as the physiological drivers of elephant crop‐raiding behaviour, using multidisciplinary sciences.
Two physiological proxies, gastrointestinal parasite infestations (GPI) and faecal glucocorticoid metabolite (fGCM) concentrations, common in animal ecophysiology, were used to help understand differences or motivations in the preferences of crops by elephant raiders.
The results show, for the first time, that forest elephants may increase the frequency of crop raiding according to GPI, indicating a self‐medication behaviour. Increases in parasitism prevalence (PP) and parasitism intensity (PI) in sampled boluses led to 28% and 0.16% more intakes of all crops, respectively. Parasitism prevalence (PP) increases in elephant boluses also led to 16% and 25% more bananas and papaya intakes, respectively, while PI increases in boluses led to 0.1% more intakes of both bananas and papaya plants. No such predictions were found for other crops (cassava and palm plant), nor for natural food species intakes. Furthermore, fGCM concentrations were not related to elephant crop raiding. Results highlight a trade‐off between the benefit of elephants raiding crops and the danger of encountering farmers by adopting nocturnal crop‐raiding behaviours.
Practical implication. We propose that elephants may choose specific plant parts while raiding crops as a self‐medication behaviour. We further discuss the importance of forest elephant conservation as they are not only forest engineers but also appear to be self‐medication specialists, which could possibly help humans cope with present and future health issues. Further understanding of that self‐medication behaviour can help communities cohabiting with forest elephants to focus on the broader health benefits rather than solely on the immediate issue of crop damage.
Disciplines :
Agriculture & agronomy Environmental sciences & ecology Phytobiology (plant sciences, forestry, mycology...) Veterinary medicine & animal health Life sciences: Multidisciplinary, general & others
Author, co-author :
Ngama, Steeve ; Université de Liège - ULiège > Département GxABT > Gestion des ressources forestières ; Centre National de la Recherche Scientifique et Technologique (CENAREST) Libreville Gabon ; SCOOPS‐ELABE (Agricultural and Conservation NGO) Libreville Gabon
Bindelle, Jérôme ; Université de Liège - ULiège > Département GxABT > Animal Sciences (AS)
Brown, Janine L.; Center for Species Survival, Smithsonian National Zoo & Conservation Biology Institute Washington District of Columbia USA
Poulsen, John R. ; Nicholas School of the Environment Duke University Durham North Carolina USA ; The Nature Conservancy Boulder Colorado USA
Hornick, Jean-Luc ; Université de Liège - ULiège > Département de gestion vétérinaire des Ressources Animales (DRA)
Linden, Annick ; Université de Liège - ULiège > Département des maladies infectieuses et parasitaires (DMI) > Santé et pathologies de la faune sauvage
Korte, Lisa; U.S. Fish and Wildlife Service Washington District of Columbia USA
Doucet, Jean-Louis ; Université de Liège - ULiège > TERRA Research Centre > Gestion des ressources forestières
Paris, Stephen; Center for Species Survival, Smithsonian National Zoo & Conservation Biology Institute Washington District of Columbia USA
Ahlering, M. A., Millspaugh, J. J., Woods, R. J., Western, D., & Eggert, L. S. (2011). Elevated levels of stress hormones in crop-raiding male elephants: Elevated stress in crop-raiding elephants. Animal Conservation, 14(2), 124–130. https://doi.org/10.1111/j.1469-1795.2010.00400.x
Baba, H., & Onanuga, A. (2011). Preliminary phytochemical screening and antimicrobial evaluation of three medicinal plants used in Nigeria. African Journal of Traditional, Complementary, and Alternative Medicines, 8(4), 387–390. https://doi.org/10.4314/ajtcam.v8i4.7
Bates, D., Mächler, M., Bolker, B., & Walker, S. (2015). Fitting linear mixed-effects models using lme4. Journal of Statistical Software, 67(1), 1–48. https://doi.org/10.18637/jss.v067.i01
Beirne, C., Meier, A. C., Brumagin, G., Jasperse-Sjolander, L., Lewis, M., Masseloux, J., Myers, K., Fay, M., Okouyi, J., White, L. J. T., & Poulsen, J. R. (2020). Climatic and resource determinants of forest elephant movements. Frontiers in Ecology and Evolution, 8, 14.
Bertschinger, H., & Caldwell, P. (2016). Fertility suppression of some wildlife species in southern Africa-a review. Reproduction in Domestic Animals, 51, 18–24. https://doi.org/10.1111/rda.12783
Biru, Y., & Bekele, A. (2012). Food habits of African elephant (Loxodonta africana) in Babile elephant sanctuary, Ethiopia. Tropical Ecology, 53(1), 43–52.
Blake, S., Deem, S. L., Mossimbo, E., Maisels, F., & Walsh, P. (2009). Forest elephants: Tree planters of the Congo: Forest elephants, seed dispersal, and trees. Biotropica, 41(4), 459–468. https://doi.org/10.1111/j.1744-7429.2009.00512.x
Blaustein, A. R., Gervasi, S. S., Johnson, P. T. J., Hoverman, J. T., Belden, L. K., Bradley, P. W., & Xie, G. Y. (2012). Ecophysiology meets conservation: Understanding the role of disease in amphibian population declines. Philosophical Transactions of the Royal Society, B: Biological Sciences, 367(1596), 1688–1707. https://doi.org/10.1098/rstb.2012.0011
Bolker, B. M., Brooks, M. E., Clark, C. J., Geange, S. W., Poulsen, J. R., Stevens, M. H. H., & White, J.-S. S. (2009). Generalized linear mixed models: A practical guide for ecology and evolution. Trends in Ecology & Evolution, 24(3), 127–135. https://doi.org/10.1016/j.tree.2008.10.008
Bradshaw, D. (2003). Vertebrate ecophysiology: An introduction to its principles and applications. Cambridge University Press.
Bradshaw, D. (2010). Ecophysiology and conservation of wildlife in Western Australia. Journal of the Royal Society of Western Australia, 93, 153–164.
Breuer, T., & Ngama, S. (2021). Les hommes et les éléphants en Afrique Centrale: Conflits et coexistence dans et autour des aires protégées. In Etats des aires protégées d'Afrique Centrale 2020 (p. 48). COMIFAC.
Bryan, H. (2013). Parasites and hormones as non-invasive bioindicators of ecophysiology in Carnivores [PhD Thesis]. University of Calgary.
Bush, E. R., Whytock, R. C., Bahaa-el-din, L., Bourgeois, S., Bunnefeld, N., Cardoso, A. W., Dikangadissi, J. T., Dimbonda, P., Dimoto, E., Edzang Ndong, J., Jeffery, K. J., Lehmann, D., Makaga, L., Momboua, B., Momont, L. R. W., Tutin, C. E. G., White, L. J. T., Whittaker, A., & Abernethy, K. (2020). Long-term collapse in fruit availability threatens Central African forest megafauna. Science, 370(6521), 1219–1222. https://doi.org/10.1126/science.abc7791
Chiyo, P. I., Lee, P. C., Moss, C. J., Archie, E. A., Hollister-Smith, J. A., & Alberts, S. C. (2011). No risk, no gain: Effects of crop raiding and genetic diversity on body size in male elephants. Behavioral Ecology, 22(3), 552–558. https://doi.org/10.1093/beheco/arr016
Chiyo, P. I., Moss, C. J., & Alberts, S. C. (2012). The influence of life history milestones and association networks on crop-raiding behavior in male African elephants. PLoS One, 7(2), e31382. https://doi.org/10.1371/journal.pone.0031382
Chota, A., Sikasunge, C. S., Phiri, A. M., Musukwa, M. N., Haazele, F., & Phiri, I. K. (2010). A comparative study of the efficacy of piperazine and Carica papaya for the control of helminth parasites in village chickens in Zambia. Tropical Animal Health and Production, 42(3), 315–318. https://doi.org/10.1007/s11250-009-9432-6
De La Torre, J. A., Cheah, C., Lechner, A. M., Wong, E. P., Tuuga, A., Saaban, S., Goossens, B., & Campos-Arceiz, A. (2022). Sundaic elephants prefer habitats on the periphery of protected areas. Journal of Applied Ecology, 59(12), 2947–2958. https://doi.org/10.1111/1365-2664.14286
Deepa, P., Sowndhararajan, K., Kim, S., & Park, S. J. (2018). A role of Ficus species in the management of diabetes mellitus: A review. Journal of Ethnopharmacology, 215, 210–232. https://doi.org/10.1016/j.jep.2017.12.045
DeGabriel, J. L., Moore, B. D., Foley, W. J., & Johnson, C. N. (2009). The effects of plant defensive chemistry on nutrient availability predict reproductive success in a mammal. Ecology, 90(3), 711–719. https://doi.org/10.1890/08-0940.1
Dubost, J.-M., Deharo, E., Palamy, S., Her, C., Haekovilay, C., Vichith, L., Duffilot, S., & Krief, S. (2022). Savoirs médicinaux interspécifiques et interactions entre cornacs et éléphants dans le district de Thongmyxay au Laos. Revue d'ethnoécologie, 22, 8–16. https://doi.org/10.4000/ethnoecologie.9553
Fairet, E. M. M. (2012). Vulnerability to crop raiding an interdisciplinary investigation in Loango National Park, Gabon [PhD Thesis]. Durham University, UK.
Finch, T. M. (2013). A noninvasive approach to understanding adaptation, crop raiding behavior, and the fecal microbiota of the African elephant [PhD Thesis, University of Missouri-Columbia]. https://doi.org/10.32469/10355/44656
Freeman, E. W., Abbondanza, F. N., Meyer, J. M., Schulte, B. A., & Brown, J. L. (2010). A simplified method for monitoring progestagens in African elephants under field conditions: Field progestagen test for elephants. Methods in Ecology and Evolution, 1(1), 86–91. https://doi.org/10.1111/j.2041-210X.2009.00004.x
Ganswindt, A., Münscher, S., Henley, M., Palme, R., Thompson, P., & Bertschinger, H. (2010). Concentrations of faecal glucocorticoid metabolites in physically injured free-ranging African elephants Loxodonta africana. Wildlife Biology, 16(3), 323–332. https://doi.org/10.2981/09-081
Gobush, K. S., Edwards, C. T. T., Maisels, F., Wittemyer, G., Balfour, D., & Taylor, R. D. (2021). Loxodonta cyclotis. The IUCN Red List of Threatened Species. [Data set]. International Union for Conservation of Nature https://doi.org/10.2305/IUCN.UK.2021-1.RLTS.T181007989A181019888.en
Greene, A. M., Panyadee, P., Inta, A., & Huffman, M. A. (2020). Asian elephant self-medication as a source of ethnoveterinary knowledge among Karen mahouts in northern Thailand. Journal of Ethnopharmacology, 259, 112823. https://doi.org/10.1016/j.jep.2020.112823
Gregory, L., Yoshihara, E., Ribeiro, B. L. M., Silva, L. K. F., Marques, E. C., Meira, E. B. S., Rossi, R. S., Sampaio, P. H., Louvandini, H., & Hasegawa, M. Y. (2015). Dried, ground banana plant leaves (Musa spp.) for the control of Haemonchus contortus and Trichostrongylus colubriformis infections in sheep. Parasitology Research, 114(12), 4545–4551. https://doi.org/10.1007/s00436-015-4700-z
Hart, B. L., & Hart, L. A. (2018). How mammals stay healthy in nature: The evolution of behaviours to avoid parasites and pathogens. Philosophical Transactions of the Royal Society, B: Biological Sciences, 373, 1–10.
Hoare, R. (2012). Lessons from 15 years of human elephant conflict mitigation. Pachyderm, 51, 60–74.
Huffman, M. A. (2022). Folklore, animal self-medication, and phytotherapy–something old, something new, something borrowed, some things true. Planta Medica, 88, 187–199. https://doi.org/10.1055/a-1586-1665
Hutchings, M. R., Athanasiadou, S., Kyriazakis, I., & Gordon, I. J. (2003). Can animals use foraging behaviour to combat parasites? Proceedings of the Nutrition Society, 62(2), 361–370. https://doi.org/10.1079/PNS2003243
Jachowski, D. S., Montgomery, R. A., Slotow, R., & Millspaugh, J. J. (2013). Unravelling complex associations between physiological state and movement of African elephants. Functional Ecology, 27(5), 1166–1175. https://doi.org/10.1111/1365-2435.12118
Kely, M. R., Kouakou, C. Y., Béné, J.-C. K., Tiedoué, M. R., Diarrasouba, A., Tondossama, A., Kuehl, H. S., & Waltert, M. (2021). Research and tourism affect positively the occupancy pattern of Loxodonta cyclotis (Elephantidae) in Taï National Park, Côte D'ivoire. Nature Conservation Research, 6(1), 12–21. https://doi.org/10.24189/ncr.2021.012
Kenfack, C. E. (2013). Le Paysage Monte Alen/Monts De Cristal. brief CIFOR, 19, 4.
Kolowski, J. M., Blake, S., Kock, M. D., Lee, M. E., Henderson, A., Honorez, A., & Alonso, A. (2010). Movements of four forest elephants in an oil concession in Gabon, Central Africa: Elephant movements in an oil concession. African Journal of Ecology, 48(4), 1134–1138. https://doi.org/10.1111/j.1365-2028.2009.01204.x
Krishna, K. L., Paridhavi, M., & Patel, J. A. (2008). Review on nutritional, medicinal and pharmacological properties of Papaya (Carica papaya Linn.). Natural Product Radiance, 7, 364–373.
Laguardia, A., Bourgeois, S., Strindberg, S., Gobush, K. S., Abitsi, G., Bikang Bi Ateme, H. G., Ebouta, F., Fay, J. M., Gopalaswamy, A. M., Maisels, F., Simira Banga Daouda, E. L. F., White, L. J. T., & Stokes, E. J. (2021). Nationwide abundance and distribution of African forest elephants across Gabon using non-invasive SNP genotyping. Global Ecology and Conservation, 32, e01894. https://doi.org/10.1016/j.gecco.2021.e01894
Marie-Magdeleine, C., Boval, M., Philibert, L., Borde, A., & Archimède, H. (2010). Effect of banana foliage (Musa x paradisiaca) on nutrition, parasite infection and growth of lambs. Livestock Science, 131(2–3), 234–239. https://doi.org/10.1016/j.livsci.2010.04.006
Meyer, J. M., Honig, N., & Hadly, E. A. (2022). Diet DNA reveals novel African Forest elephant ecology on the grasslands of The Congo Basin. Environmental DNA, 4(4), 846–867. https://doi.org/10.1002/edn3.296
Munshi-South, J., Tchignoumba, L., Brown, J., Abbondanza, N., Maldonado, J. E., Henderson, A., & Alonso, A. (2008). Physiological indicators of stress in African forest elephants (Loxodonta africana cyclotis) in relation to petroleum operations in Gabon, Central Africa. Diversity and Distributions, 14(6), 995–1003. https://doi.org/10.1111/j.1472-4642.2008.00509.x
Nakandé, A., Belem, A. M. G., Nianogo, A. J., & Jost, C. (2007). Parasites gastro-intestinaux des éléphants dans la Réserve Partielle de Pama, Burkina Faso. Pachyderm, 42, 11.
Nchanji, A. C., Forboseh, P. F., & Powell, J. A. (2008). Estimating the defaecation rate of the African forest elephant (Loxodonta cyclotis) in Banyang-Mbo Wildlife Sanctuary, south-western Cameroon. African Journal of Ecology, 46(1), 55–59. https://doi.org/10.1111/j.1365-2028.2007.00808.x
Ngama, S., Bindelle, J., Brown, J. L., & Vermeulen, C. (2025). Data from: Are crop fields pharmacies for megaherbivores? From ecophysiological studies of elephant (Loxodonta cyclotis) crop raiders in Gabon [Data set]. Dryad. https://doi.org/10.5061/dryad.7wm37pw1p
Ngama, S., Bindelle, J., Poulsen, J. R., Hornick, J.-L., Linden, A., Korte, L., Doucet, J.-L., & Vermeulen, C. (2019). Do topography and fruit presence influence occurrence and intensity of crop-raiding by forest elephants (Loxodonta africana cyclotis)? PLoS One, 14(3), e0213971. https://doi.org/10.1371/journal.pone.0213971
Oduor, S., Brown, J., Macharia, G. M., Boisseau, N., Murray, S., & Obade, P. (2020). Differing physiological and behavioral responses to anthropogenic factors between resident and non-resident African elephants at Mpala Ranch, Laikipia County, Kenya. PeerJ, 8, e10010. https://doi.org/10.7717/peerj.10010
Osborn, F. V. (2004). Seasonal variation of feeding patterns and food selection by crop-raiding elephants in Zimbabwe. African Journal of Ecology, 42(4), 322–327. https://doi.org/10.1111/j.1365-2028.2004.00531.x
Pattanayak, S. (2024). Self-treatment among animals by using succulent herbs to fight against parasites and their possible use as human medicine. Exploratory Animal and Medical Research, 14, 18–28. https://doi.org/10.52635/eamr/14(S1)18–28
Pokharel, S. S., & Brown, J. L. (2023). Physiological plasticity in elephants: Highly dynamic glucocorticoids in African and Asian elephants. Conservation Physiology, 11(1), coad088. https://doi.org/10.1093/conphys/coad088
Pretorius, Y., Stigter, J. D., de Boer, W. F., van Wieren, S. E., de Jong, C. B., de Knegt, H. J., Grant, C. C., Heitkönig, I., Knox, N., Kohi, E., Mwakiwa, E., Peel, M. J. S., Skidmore, A. K., Slotow, R., van der Waal, C., van Langevelde, F., & Prins, H. H. T. (2012). Diet selection of African elephant over time shows changing optimization currency. Oikos, 121(12), 2110–2120. https://doi.org/10.1111/j.1600-0706.2012.19680.x
Santos, J. M., Campesatto, E. A., de Assis Bastos, M. L., & Lúcio, I. M. L. (2012). Evaluation of biological activity of Musa spp (banana) integrative literature review.pdf. The Journal of Nursing, 6, 1948–1957.
Shaffer, L. J., Khadka, K. K., Van Den Hoek, J., & Naithani, K. J. (2019). Human-elephant conflict: A review of current management strategies and future directions. Frontiers in Ecology and Evolution, 6, 235. https://doi.org/10.3389/fevo.2018.00235
Sudhakar, N, Theivanai, & Vidhya, R. (2014). Potential medicinal properties of Carica papaya Linn. A mini review. International Journal of Pharmacy and Pharmaceutical Sciences, 6 (2), 1–4.
Terada, S., Yobo, C. M., Moussavou, G.-M., & Matsuura, N. (2021). Human-elephant conflict around Moukalaba-Doudou National Park in Gabon: Socioeconomic changes and effects of conservation projects on local tolerance. Tropical Conservation Science, 25, 194008292110267. https://doi.org/10.1177/19400829211026775
Theuerkauf, J., & Gula, R. (2010). Towards standardisation of population estimates: Defecation rates of elephants should be assessed using a rainfall model. Annales Zoologici Fennici, 47(6), 398–402. https://doi.org/10.5735/086.047.0603
Turkalo, A. K., Wrege, P. H., & Wittemyer, G. (2017). Slow intrinsic growth rate in forest elephants indicates recovery from poaching will require decades. Journal of Applied Ecology, 54(1), 153–159. https://doi.org/10.1111/1365-2664.12764
Villalba, J. J., Miller, J., Ungar, E. D., Landau, S. Y., & Glendinning, J. (2014). Ruminant self-medication against gastrointestinal nematodes: Evidence, mechanism, and origins. Parasite, 21, 31. https://doi.org/10.1051/parasite/2014032
Walker, K. L. (2012). Labor costs and crop protection from wildlife predation: The case of elephants in Gabon. Agricultural Economics, 43(1), 61–73. https://doi.org/10.1111/j.1574-0862.2011.00565.x
Winter, B. (2014). Linear models and linear mixed effects models in R with linguistic applications. arXiv:1308.5499 [Cs]. http://arxiv.org/pdf/1308.5499.pdf
Yoh, N., Mbamy, W., Gottesman, B. L., Froese, G. Z. L., Satchivi, T., Obiang Ebanega, M., Carlson, L., Koto, S. E., Özdoğan, M., Seaman, D. J. I., Maicher, V., Malinowski, H., Poulsen, J., Ebang Mbélé, A., & Buřivalová, Z. (2024). Impacts of logging, hunting, and conservation on vocalizing biodiversity in Gabon. Biological Conservation, 296, 110726. https://doi.org/10.1016/j.biocon.2024.110726
