Masai Giraffe (Giraffa Camelopardalis Tippelskirchi) Population and Landuse Trends in the Tsavo Landscape, Kenya

Abstract

This study analyzed giraffe (Giraffa camelopardalis tippelskirchi) population and land use trends in the Tsavo landscape. The main objectives of the study were: to assess the past and current distribution of giraffe; to analyze how land use and land cover has changed in the Tsavo landscape from the 1985 to 2020; and to determine how Land Use Land Cover (LULC) change and other factors influence giraffe distribution within the Tsavo landscape. Tsavo landscape was divided in to five regions, Tsavo West National Park (TWNP), Tsavo East National Park (TENP), South Kitui National Reserve (SKNR), Taita Ranches and Rombo Group Ranch. Current giraffe population, density, age structure and sex structure were established using road transect counts in the different regions. Data were also collected on the status and distribution of water sources during the road transect surveys. Past giraffe population was determined through review of secondary data from past large mammal censuses in the study area. Landsat satellite images for the years 1985,1999,2010 and 2020 were classified into various land and vegetation classes and later analyzed to establish LULC change. Giraffe density differed significantly among all the regions (H = 12.99, df = 4, P<0.05) in the Tsavo landscape; Rombo Group Ranch had the highest density followed by TWNP. Taita Ranches came in third followed by TENP, there were no giraffe sightings in SKNR. There was a significantly higher number of female giraffe than male giraffe in the Tsavo landscape (χ2= 36.94, df = 1, P<0.05), the male: female sex ratio was 1:1.63. Giraffe age distribution varied significantly within the different regions (χ2 = 38.34, df = 18, P<0.05), TENP had the highest proportion of adults followed by Rombo Group Ranch, TWNP came in third but Taita Ranches had the least proportions of adults. Total giraffe population showed a significantly declining trend since the 1970’s (R = -0.77, P<0.05). The number of giraffe sightings decreased significantly with increase in distance to permanent rivers (R = -0.88, P<0.05) and wet artificial waterpoints (R= - 0.93, P<0.05). Giraffe sightings decreased though not significantly with increasing distance to seasonal rivers (R = -0.69, P>0.05) and dry artificial water points (R= -0.48, P>0.05). Chi-squared tests showed that there was a significant difference in the area covered by forest (χ2 = 286.91, df = 3, P < 0.05), bushland and Commiphora thicket (χ2 = 355.21, df = 3, P < 0.05), Acacia woodland (χ2 = 4820.30, df = 3, P <0.05) and woodland (χ2 = 411.97, df = 3, P < 0.05). There was a significant increase in the area covered by grassland (χ2 = 2678.32, df = 3, P <0.05), bareland (χ2 = 3413.81, df = 3, P < 0.05), agriculture (χ2 = 1626.22, df = 3, P <0.05) and settlement (χ2 = 448.97, xii df = 3, P < 0.05). There was no significant change in the area covered by water (χ2 = 3.42, df = 3, P < 0.05). The study also conducted a finer scale LULC change analysis on Rombo Group Ranch between 1985 and 2020. Chi-squared tests revealed that there was significant increase in the area covered by agriculture (χ2 = 62.62, df = 3, P <0.05) and bareland (χ2 = 19.45, df = 3, P < 0.05). The area covered by Acacia woodland decreased significantly (χ2 = 18.12, df = 3, P < 0.05). There was no significant change on the area under woodland (χ2 = 6.99, df = 3, P > 0.05), grassland (χ2 = 4.55, df = 3, P > 0.05) and settlement (χ2 = 0.83, df = 3, P > 0.05). The study observed that the overall Masai giraffe population was decreasing over the years in the Tsavo landscape, while LULC types that compromise giraffe conservation were observed to be increasing. The study proposed formation of conservancies and formulation of land use plans in community and private ranches to curb the development of LULC regimes that conflict with giraffe conservation in the Tsavo landscape.