AMERICAN JOURNAL OF SCIENTIFIC AND INDUSTRIAL RESEARCH © 2016,Science Huβ, http://www.scihub.org/AJSIR ISSN: 2153-649X, doi:10.5251/ajsir.2016.7.2.41.49 Ecological behaviour of common hippopotamus (Hippopotamus amphibius, LINNAEUS, 1758) in boye wetland, jimma, ethiopia Sefi Mekonen1*, Birnesh Hailemariam2 1. Madda Walabu University, Department of Ecotourism and Biodiversity Conservation, P.O. Box 247, Ethiopia, Email [email protected] 2. Wollega University, Department of Biology, P.O. Box 395, Ethiopia Email [email protected] ABSTRACT A study on the ecological behaviour of hippopotamus (Hippopotamus amphibius) was conducted in Boye wetland between February and May, 2013. The behavioural activity and event patterns were studied with 30 minutes interval following a male and female focal sampled individual. The feeding preferences of hippopotamuses determined by collecting and identifying the plant species that consumed by hippopotamus. Resting comprises the majority of their activity time with 42.50% followed by moving 34.16%, feeding 19.63% and mating 3.71%. Barking and yawning events spent 51.18% and 48.82% of their time respectively. Males spent more time only in resting records than females, while females were active in all behavioural activity and event patterns except mating activity. Feeding and moving peak activities were observed early morning and late afternoon hours with resting peak during the mid-day, while barking and yawning events were mostly increased to afternoon both in male and female hippopotamus. Hippopotamus consumed a total of 26 species of plant. Of these, Eriochloa fatmensis 11.68%, Typha latifolia 9.91%, Echinocloa pyramidalis 9.59% and Cynodon dactylon 8.45% were the top four species of plants contributing 39.63% of their overall diet. Keywords: Behavioural activity, Boye wetland, Ecological behaviour, Feeding ecology, Hippopotamus artiodactyls (Nowak, 1991). In reproduction INTRODUCTION behaviours of hippopotamus, females mate with the Common hippopotamus (Hippopotamus amphibius) males in the water and, 8 months gestation, 12 is the third largest herbivorous African mammal next months lactation, 4 months an oestrus; and will give to African elephant (Loxodonta africana) and birth in shallow water as well or on land (Martin, Rehinosorus (Diceros bicornis). H. amphibius is an 2005). Twins are rare; the sex ratio at birth is 1:1 unmistakable species, with a plump and thick-body, (Post, 2000). huge and round-head; great, bulk and short limbs, very large tusk-like canines, broad snout, and short- As its name suggests, the H. amphibius is an tail and short stocky legs. Their eyes, ears, and amphibious creature, which has two main habitat nostrils are placed on the high roof of the skull requirements: water to rest in during the day and (Grubb, 1993). The thin epidermis of the skin makes grass to graze on at night (Lewisson and Carter, hippopotamus vulnerable to desiccation. For 2004). The hippopotamus is found in all types of additional protection from the sun, their skin secretes permanent freshwater habitats, including ponds, a natural sunscreen substance known as “blood rivers, lakes, waterholes with gently sloping banks sweat”. Nevertheless, their skin will crack if exposed surrounded by grazing areas. It avoids extremely to air for too long due to lack of sweat glands dense swampy vegetation and fast-moving (Eltringham, 1993). waterways with rocky outcroppings (Lewson, 2007). Hippopotamus is a selective grazer consuming 35- Hippopotamus has aggressive behaviour toward 50 kg of grass or about 2.5% body weight daily people and is said to be the most dangerous of wild (Chansa et al., 2011; Théophile et al., 2012). It differs Am. J. Sci. Ind. Res., 2016, 7(2): 41-49 from other mega-herbivores in having a dual (Fig. 1). It is one of the wetlands found in this region, requirement of daily living space in water and an located about 4 km from the center of Jimma town in open grazing range (Eltringham, 1993). the East at 7° 39′38″ N and 36°52′14″ E. The current area is 110.03 hectare. The wetland is permanent Existing knowledge on hippopotamus behaviour and type with variable water level at different seasons. It ecology is still inadequate and the obtrusive and is continuously fed by ground water and/or spring often adversarial character of hippopotamus-human flow, as well as surface flow during the wet season. interactions (Dudley, 1998). These points have led to The study area receives a rainfall ranges the formulation of the objective of this study. between1416.20 and 1586.70mm per annum with an Therefore, the research on behavioural ecology of average annual rainfall of 1513.28mm having the hippopotamus in Boye wetland is crucial in its heaviest concentration from June to September. The contribution to address some of the gap areas on average maximum and minimum temperature is hippopotamus research. 27.29°C and 11.83°C respectively with a mean daily temperature of 19.56°C. MATERIALS AND METHODS Study area: ye wetland is found in Jimma Zone of Oromiya Regional State, in southwestern Ethiopia Fig. 1: Map of study area has also very rich macroinvertebrate taxa (Desta, Boye wetland is the areas of flat lands surrounded by 2006). small hills having dominant vegetation of Typha grasses, Sedges (Cyperacea), and some other grass Methods: Focal animal sampling method was used species. With regarding to fauna, hippopotamus and to study the diurnal activity and event patterns of a greater number of species of birds are found (Desta hippopotamuses, focusing two focal sampled and Mengistu, 2009; Mekonnen and Aticho, 2011). It individuals following the method of Altman (1974) and 42 Am. J. Sci. Ind. Res., 2016, 7(2): 41-49 Martin and Bateson (2007) in Boye wetland between plant species was determined by sum its frequency of February and May, 2013. A pair of focal animals (an biting or feeding sign observation divided by sum of adult male and adult female) was followed and data frequency of all food plant collection at feeding sites on their diurnal activities were recorded every 30 multiplied by hundred throughout study periods (see minutes with five minutes sampling gap between equation 1) (Theophile et al., 2012). 07:00-18:00 h except 13:00-14:00 h. Focal animals were selected randomly and clearly identified by FSi CSi 100 distinctive morphological characteristics (skin mark or n --------------------Equation 1 skin colour) by using binoculars or naked eye. t Observations were made for five consecutive days FS for each four months in Boye wetland. A total of 20 i1 days behavioural observation was done. n At each sampling point, the major activities of two Where FSt = the total frequency of all individual animals were recorded separately as i1 feeding, moving, resting or standing, mating, barking collected species. and yawning. Feeding, moving, resting and mating activities were recorded as behaviour activities Data Analysis: Moreover, Statistical package (stets), while barking and yawning displays were software SPSS version 16.0 was used to analyze the recorded the frequency or events (Martin and data. Behavioural pattern variations between male Bateson, 2007; Timbuka, 2012). Events are and female were tested using t-tests. Descriptive behavioural patterns of relatively short duration such statistics were carried out to calculate frequencies, as vocalization or discrete body movements (Martin and to allow cross-tabulations. All over, 0.05 level of and Bateson, 2007), as opposed to behavioural significance used as the criterion for comparison of activities which are relatively longer duration such as the mean and confidence interval at 95%. standing, resting or feeding. RESULT The methods used to determine the feeding preferences of hippopotamuses included collecting Diurnal activity and event patterns of and identifying the plant species they consumed by hippopotamus: A total of 1368 behavioural records hippopotamus. The plant species consumed by were made from an adult male and female focal hippopotamus were studied by examination of fresh sampled hippopotamuses. Of these 647 were diurnal feeding signs that was observed from foraging area activities or stets such as feeding, moving, resting and in the crop lands during patrol early in the and mating and the rest 721 were barking and morning after the passage of the animal (Theophile et yawning events. As table 1 shown adult al., 2012). In addition to feeding sign observations, hippopotamuses were spent feeding (19.63%), the diet of hippopotamus was carried out by day time moving (34.16%), passive (lying and standing) direct feeding observation. The food plants, which (42.50%) and mating (3.71%) of their behavioural having been bitten or plucked by the animal were activities. However, 51.18% and 48.82% of collected, pressed and then identified with help of a behaviours were displayed barking and yawning taxonomist in Botanical Herbarium in Jimma events respectively. University. The percentage of feeding preference of a Table 1. Diurnal activity and event records of male and female hippopotamus Sex Behavioural Activities Total Behavioural Events Total Feeding Moving Resting Mating Barking Yawning Male 40 104 148 12 304 150 163 313 Female 87 117 127 12 343 219 189 408 Total 127 221 275 24 647 369 352 721 (19.63%) (34.16%) (42.50%) (3.71%) (51.18%) (48.82%) 43 Am. J. Sci. Ind. Res., 2016, 7(2): 41-49 Comparison of activity and event budgets behavioural activities and events than females between male and female: Time allocated to (53.01% and 56.59%), respectively. As the figure 2 different activities and events by adult female and shown, male was spent more time for only resting male over the entire study period are provided in activity as compare to female, but mating activities table 1. Out of 647 and 721 behavioural activities and were equal for male and female, hence unfortunately events respectively, male hippopotamuses were the focal sample was selected the mating pair at display less percent (46.99% and 43.41%) of observation period.