Warthog (Phacochoerus africanus) plays a key ecological role in African savannas, yet its population status remains poorly documented in South Sudan. This study present the first standardized, protocol-based assessment of warthog density and sightings predictors in Nimule National Park (NNP), South Sudan. It also examine its density variations across the continent. The line transect sampling method was employed to assess the population. A total of 20 transects were laid in three habitat types covering a distance of 264km in 2015 and 2016. DISTANCE sampling estimated approximately 4,000 warthogs within the 256 km2 core zone during 2015–2016, substantially exceeding the 265 individuals recorded in 2000, although remaining below historical estimates from 1987. Warthog sightings and abundance increased 16–22-fold between survey years, indicating strong interannual fluctuations likely linked to environmental conditions and forage availability. GLMs identified burrow availability as a significant predictor of both sightings and abundance, whereas human disturbance showed no significant effect. Comparative GLMM analyses across Africa demonstrated that local site-level factors were more influential than broader macrogeographical effects in shaping density patterns. Although the modeled density at Nimule in 2015-2016 ranked high among continental populations, comparisons revealed considerable variation in warthog densities among sites within countries. The NNP supports one of the highest warthog densities in Africa, emphasizing its conservation importance and the value of long-term, standardized monitoring to better define management strategies for savannah ungulates under variable ecological and anthropogenic pressures. Despite currently high densities, warthog populations in Nimule National Park show strong interannual variability and dependence on burrow-rich dry-season refugia, indicating that sustained multi-year monitoring, habitat protection, and consistent local management are essential to maintain their favourable conservation status.
AbduA.DatikoD. (2017). Population Size, habitat association of Common Warthog (Phacochoerus africanus) and their impact on agricultural crops around Diregudo forest in Gololcha woreda, South East, Ethiopia. IJ Sci. Res. Publ, 7, 192-218.
2.
AbdullahS. (2015). Report on warthog death at Nimule National Park disease. 12th to 16th February 2015. Unpublished report, Ministry of Tourism and wildlife Conservations, South Sudan, Juba. pp 28.
3.
AdeolaA. J.AdeyemoA. I.EjidikeB. N. (2019). Population status and habitat preferences of common warthog (Phacochoerus africanus) in Kainji Lake National Park, Niger State Nigeria. Journal of Research in Forestry, Wildlife and Environment, 11(4), 64-69.
4.
AdeolaA. J.AdeyemoA. I.EjidikeB. N.OlaniyiO. E.AkandeO. A.AjayiS. R.AzeezO. K. (2021). Conservation status and habitat preferences of common warthog (Phacochoerus africanus) in Old Oyo National Park, Nigeria. Journal of Applied Sciences and Environmental Management, 25(1), 87-92.
5.
AndersonD. R.BurnhamK. P.LubowB. C.ThomasL.CornP. S.MedicaP.MarlowR. W. (2001). Field trials of line transect methods applied to estimation of desert tortoise abundance. Journal of Wildlife Management, 65(3):583-597.
6.
AndersonN. E.BessellP. R.MubangaJ.ThomasR.EislerM. C.FevreE. M.WelburnS. C. (2016). Ecological monitoring and health research in Luambe National Park, Zambia: Generation of baseline data layers. EcoHealth, 13(3), 511-524.
7.
ApioA.PlathM.WronskiT. (2015). Recovery of ungulate populations in post-civil war Akagera National Park, Rwanda. Journal of East African Natural History, 104(1-2), 127-141.
8.
AsayeB.TekalignW.DobamoT. (2024). Density of wild animal populations and their conflicts with nearby farmers in southwest Ethiopia, Mankira Forest.
9.
AugustineD. J. (2010). Response of native ungulates to drought in semi–arid Kenyan rangeland. African Journal of Ecology, 48, 1009–1020.
10.
BarnesM. (2016). Protected areas are helping save our favourite animals-but let’s not forget the others. The Conversation. https://theconversation.com/Protected areas are helping save our favourite animals–but let’s not forget the others.
11.
BertramB. C. R. (1979). Studying predators. 2nd ed.African Wildlife Foundation, Nairobi, Kenya.
BholaN.OgutuJ. O.PiephoH. P.SaidM. Y.ReidR. S.HobbsN. T.OlffH. (2012). Comparative changes in density and demography of large herbivores in the Masai Mara Reserve and its surrounding human-dominated pastoral ranches in Kenya. Biodiversity and Conservation, 21(6), 1509-1530.
14.
BoltonM. (1972). Report on a wildlife survey of South East Ethiopia. Walia, 1972(4), 19-31.
15.
BosheJ. I.1984. Demographic characteristics of the warthog population of the eastern Selous Game Reserve, Tanzania. Afr. f. Ecol, 22:43-47.
16.
BowmanJ.C.RobitailleJ.-F. (2005). An assessment of expert-based marten habitat models used for forest management in Ontario. The Forestry Chronicle, 81(6): 801–807.
17.
BradleyR. M. (1968). Some aspects of the ecology of the warthog (Phacochoerus aethiopicus Pallas) in Nairobi National Park(Doctoral dissertation, University of East Africa).
18.
BucklandS. T.AndersonD. R.BurnhamK. P.LaakeJ. L.BorchersD. L.ThomasL. (2001). Introduction to distance sampling: estimating abundance of biological populations. Oxford University Press.
19.
BucklandS. T.AndersonD. R.BurnhamK. P.LaakeJ. L.BorchersD. L.ThomasL. (2004). Advanced distance sampling: estimating abundance of biological populations. Oxford University Press.
20.
BucklandS. T.AndersonD. R.LaakeJ. L. (1993) Distance sampling: estimating abundance of biological population. Chapman & Hall, London.
21.
ButynskiT. M.de JongY. A. (2017). Common warthog Phacochoerus africanus (Gmelin, 1788) (pp. 85-100). In: Ecology, Conservation and Management of Wild Pigs and Peccaries, edited by MellettiM.MeijaardE.; Cambridge: Cambridge University Press.
CreelS.MatandikoW.SchuetteP.RosenblattE.SanguinettiC.BandaK.VinksaM.BeckerM. (2018). Changes in African large carnivore diets over the past half–century reveal the loss of large prey. Journal of Applied Ecology, 1–9, 2908–2916. https://doi.org/10.1111/1365–2664.13227
24.
CummingD. H. M. (1982). The influence of large herbivores on savanna structure in Africa. In Ecology of tropical savannas (pp. 217-245). Berlin, Heidelberg: Springer Berlin Heidelberg.
25.
CummingD. H. M. (1999). Phacochoerus africanus: The Mammals of Africa. In: KingdonJ. S.HoffmannM. (Eds.), Academic Press, Amsterdam, The Netherlands.
26.
CunninghamP. (2016). Ecology and Conservation encounters of with common warthogs along the B1highway in north-central Namibia. Ecol Conserv, 14(2), 32-37.
27.
De JongY. A.CummingD.d'HuartJ.ButynskiT. (2016). Phacochoerus africanus (pp. 1–12). The IUCN Red List of Threatened Species.
28.
DemayaG. S.MorjanM. D.LadoT. F.GordonS. A.Di VittorioM.DendiD.LuiselliL. (2024). Population Size, Sex-Ratio and Age Structure of Hippopotamus amphibius in Nimule National Park, South Sudan. Journal of East African Natural History, 113(6), 50-58.
29.
DennyS.CoadL.JonesS.IngramD. J. (2025). Snaring and wildlife wastage in Africa: drivers, scale, impacts, and paths to sustainability. BioScience, 75, 284-297.
30.
DeribeE.BekeleA.BalakrishnanM. (2008). Population status and diurnal activity patterns of the common warthog (Phacochoerus africanus) in the Bale Mountains National Park, Ethiopia. International Journal of Ecology and Environmental Sciences, 34(2), 91-97.
31.
EdossaA.BekeleA.DebellaH. J. (2020). Social organization and activity patterns of common warthog (Phacochoerus africanus Gmelin, 1788) in Dabena Valley Forest, Western Ethiopia. Ecology and Evolutionary Biology, 5(4), 173-181.
32.
EdossaA.BekeleA.DebellaH. J. (2021). Diet preferences of common warthogs (Phacochoerus africanus) in Gassi and Haro Aba Diko controlled hunting areas, Western Ethiopia. Global Ecology and Conservation, 29, e01722.
33.
EdossaA.BekeleA.DebellaH. J. (2022). Population density and distribution of common warthog (Phacochoerus africanus Gmelin, 1788) in Dabena Valley Forest, Western Ethiopia. African Journal of Ecology, 60(3), 386-397.
34.
FischerF.LinsenmairK. E. (2001). Decreases in ungulate population densities. Examples from the Comoé National Park, Ivory Coast. Biological Conservation, 101(2), 131-135.
35.
GaidetN.FritzH.NyahumaC. (2003). A participatory counting method to monitor populations of large mammals in non-protected areas: a case study of bicycle counts in the Zambezi Valley, Zimbabwe. Biodiversity & Conservation, 12(8), 1571-1585.
36.
GaynorK. M.HojnowskiC. E.CarterN. H.BrasharesJ. S. (2018). The influence of human disturbance on wildlife nocturnality. Science, 360(6394), 1232-1235.
37.
HaywardM. W.HenschelP.O'BrienJ.HofmeyrM.BalmeG.KerleyG. I. (2006). Prey preferences of the leopard (Panthera pardus). Journal of Zoology, 270(2), 298-313.
38.
HaywardM. W.KerleyG. I. (2005). Prey preferences of the lion (Panthera leo). Journal of Zoology, 267(3), 309-322.
39.
HemaE. M.DouambaB.Di VittorioM.DendiD.GuendaW.PetrozziF.OuédraogoB.LuiselliL. (2017). Long-term (1985-2012) population fluctuations of warthog (Phacochoerus africanus) in Nazinga Game Ranch (Burkina Faso). African Journal of Ecology, 55(4), 748-753.
40.
HjertlövL. (2015). Why do the common warthog Phacochoerus africanus stay at Kichwa Tembo? Student report Swedish University of Agricultural Sciences Department of Animal Environment and Health.
41.
IUCN and World Commission on Protected Areas (WCPA) (2016). IUCN Green List of Protected and Conserved Areas: Standard, Version 1.1. Gland, Switzerland: IUCN.
42.
IUCN ESARO. (2020). The state of protected and conserved areas in Eastern and Southern Africa. State of protected and conserved areas report series no. 1. IUCN ESARO, Nairobi. Kenya.
43.
JamesN. L.BondM. L.OzgulA.LeeD. E. (2022). Trophic processes constrain seasonal ungulate distributions at two scales in an East African savanna. Journal of Mammalogy, 103(4), 956-969.
44.
KiffnerC.KiokoJ.BaylisJ.BeckwithC.BrunnerC.BurnsC.Chavez-MolinaV.CottonS.GlazikL.LoftisE.MoranM.O'NeillC., Theisinger, & KissuiB. (2020). Long‐term persistence of wildlife populations in a pastoral area. Ecology and Evolution, 10(18), 10000-10016.
KoonsD. N.IlesD. T.CaswellH. (2016). A life-history perspective on the demographic derivers of structured population dynamics in changing environments. Ecology letters, 19(9):1023-1031.
47.
LuardN.the World-Wide Fund. (1985). The wildlife parks of Africa. Michael Joseph, London, United Kingdom.
48.
MapendereC.JoriF.EtterE. M.FergusonJ. H. W. (2021). Do wild suids from Ndumo Game Reserve, South Africa, play a role in the maintenance and transmission of African swine fever to domestic pigs?Transboundary and Emerging Diseases, 68(5), 2774-2786.
49.
MarchalA.LejeuneP.BouchéP.OuédraogoM.SawadogoP.YaméogoD.YanogoF. I.VermeulenC. (2012). Status of medium–sized ungulate populations in 2010, at the Nazinga game ranch, Burkina Faso (Western Africa). Biotechnologie, Agronomie, Société et Environnement, 16, 1–7.
50.
McCleeryR.MonadjemA.ConnerL. M.AustinJ. D.TaylorP. J. (2022). Methods for ecological research on terrestrial small mammals. John Hopkins University Press.
51.
McCombB.ZuckerbergB.VeselyD.JordanC. (2010). Monitoring Animal Populations and their Habitats: A Practitioner's Guide. 1st. Ed. CRC Press. ISBN: 142007055X DOI:https://doi.org/10.1201/9781420070583
52.
MgqatsaN.JamaK.LandmanM.KerleyG. I. (2024). Understanding resource use of an invasive species: Diet of the common warthog in Eastern Cape succulent thicket. Journal of Arid Environments, 222, 105155.
53.
Ministry of Wildlife Conservation and Tourism of South Sudan & African Wildlife Foundation. (2014). Nimule National Park and Buffer Zone General Management Plan 2015-2020. Unpublished document, Ministry of Wildlife Conservation and Tourism, Juba. pp 125.
54.
MorjanM.OjokL.AckwochA.KamdallaJ.NicholasB. (2000). A pilot survey of Nimule National Park New Sudan. Unpublished report, Juba.
55.
NdiayeS. A. A. S.KabreJ. A. T.LeyeB. (2017). Warthogs population count and age groups in the Senegal River Delta: case of the Djoudj National Park and the Gueumbeul Wildlife reserve.
56.
NjorogeP.YeggoR.MuchaneM.GithiruM.NjeriT.GianiA. (2009). A survey of the large and medium sized mammals of Arawale National Reserve, Kenya. J. East Afr. Nat. Hist98: 119-128, https://doi.org/10.2982/028.098.0108.
OgutuJ. O.KulobaB.PiephoH-P.KangaE. (2017). Dominated landscape under community-based conservation: the example of Nakuru Wildlife Conservancy, Kenya. PloS One12(1): e0169730. Doi:10.171/journal.pone.0169730.
59.
OgutuJ. O.PiephoH. P.DublinH. T. (2014). Reproductive seasonality in African ungulates in relation to rainfall. Wildlife Research, 41(4), 323-342.
60.
OgutuJ. O.PiephoH. P.DublinH. T.BholaN.ReidR. S. (2008). Rainfall influences on ungulate population abundance in the Mara‐Serengeti ecosystem. Journal of Animal Ecology, 77(4), 814-829.
61.
PlumptreA. J. (2000). Monitoring mammal populations with line transect techniques in African forests. Journal of Applied Ecology, 37, 356-368.
62.
PrasanaiK.SukmasuangR.BhumpakhanN.WajjwakW.NittayaK. (2012). Population characteristics and viability of the introduced hog deer (Axis porcinus Zimmermann, 1780) in Phu Rhieo Wildlife Sanctuary, Thailand. Songklanakarin J. Sci. Technol34(3), 263-271.
63.
ReubenE. M.BrownB. P.OdhukA. E.DabitM. P.ModiM. S.SubeE. A. (2014). A suspected unknown wildlife disease infecting African warthog Phacochoerus aethiopicus in Nimule National Park, Unpublished report, Ministry of Wildlife Conservation and Tourism, South Sudan, Juba.
64.
RiemanB. (2001). Wildlife population viability under land management alternatives from an environmental impact statement. Forest Ecology and Management, 153 (1-3): 29-42.
65.
SethyJ.ChuanhanN. S. (2016). Assessing habitat use by sun bears in Namdapha Tiger Reserve, Arunachal Pradesh, India. Applied Ecology and Environmental Research, 14(1):215-26. DOI:https://doi.org/10.15666/aeer/1401_215236
66.
SinsinBTehouACDaoudaISaidouA. 2002. Abundance and species richness of larger mammals in Pendjari National Park in Benin. Mammalia66(3):369-80.
67.
SomersM. J.PenzhornB. L.RasaA. E. (1994). Home range size, range use and dispersal of warthogs in the eastern Cape, South Africa. Journal of African Zoology, 108(4), 361-374.
68.
SutherlandW. (1996). Ecological census techniques: a handbook. Cambridge University Press, Cambridge, U.K.
69.
TamratM.AtickemA.TsegayeD.NguyenN.BekeleA.EvangelistaP.FashingP.J.StensethN. C. (2020). Human–wildlife conflict and coexistence: a case study from Senkele Swayne's Hartebeest Sanctuary in Ethiopia. Wildlife Biology, 2020(3), 1-10.
70.
TaraveauF.BruD.PolletT.JeanneauM.DuhayonM.Pires LameiraE. R.Jourdan-PineauH. (2025). Population genetics of the nidicolous soft tick Ornithodoros phacochoerus in the context of African swine fever sylvatic cycle. bioRxiv, 2025-10.
71.
TeklehaimanotG.BalakrishnanM. (2017). Population status, feeding ecology and habitat association of the common warthog (Phacochoerus africanus) in Bale Mountains National Park, Ethiopia. International Journal of Ecology and Environmental Sciences, 43(3), 185-194.
72.
ThomasL.BucklandS. T.BurnhamK. P.AndersonD. R.LaakeJ. L.BorchersD. L.StrindbergS. (2002). Distance sampling. in Encyclopedia of Environmetrics, (1): 544–552. ISBN 0471 899976. John Wiley & Sons, Ltd, Chichester.
73.
ThomasL.BucklandS.T.RexstadE.A.LaakeJ. L.StrindbergS.HedleyS.L.BishopJ.R. B.MarquesT. A.BurnhamK. P. (2010). Distance software: design and analysis of distance sampling surveys for estimating population size. Journal of Applied Ecology, 47, 5-14.
74.
ThorpP. (2012). The influence of active bomas on habitat choice of the common warthog (Phacochoerus africanus). Student report. Swedish University of Agricultural Sciences Student report 387. Department of Animal Environment and Health. Ethology and Animal Welfare programme.
75.
TreydteA. C.HalsdorfS. A.WeberE.SourceP. J. E. (2006). Habitat use of warthogs on a former cattle ranch in Tanzania. The Journal of Wildlife Management, 70(5), 1285–1292.
76.
UeharaS.IhobeH. (1998). Distribution and abundance of diurnal mammals, especially monkeys, at Kasoje, Mahale Mountains, Tanzania. Anthropological Science, 106(4), 349-369.
77.
VinksM. A.CreelS.SchuetteP.RosenblattE.MatandikoW.SanguinettiC.BandaK.GoodheartB.NeckerM.ChifunteC.SimukondaC. (2020). Testing the effects of anthropogenic pressures on a diverse African herbivore community. Ecosphere, 11(3), e03067.
78.
WakeleyJ. S. (1982). Wildlife Population Ecology. Pennsylvania State University Press. 385 pp.
79.
WaltertM.MeyerB.KiffnerC. (2009). Habitat availability, hunting or poaching: what affects distribution and density of large mammals in western Tanzanian woodlands?African Journal of Ecology, 47(4), 737-746.
80.
WesternD.GrimsdellJ. J. R. (1979). Measuring the distribution of animals in relation to the environment. Handbook no. 2, 2nd edition. African Wildlife Foundation, Nairobi, Kenya.
81.
WhiteA. M. (2010). A pigheaded compromise: do competition and predation explain variation in warthog group size?Behavioral Ecology, 21(3), 485-492.
82.
WhiteA. M.CameronE. Z. (2009). Communal nesting is unrelated to burrow availability in the common warthog. Animal Behaviour, 77(1), 87-94.
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