Population density of elephants and other key large herbivores in the Amboseli ecosystem of Kenya in relation to droughts

• This paper looks at the effect of the two consecutive droughts of 2007 and 2009 on wild large mammals in Kenya/Tanzania borderland.
• All large mammal populations collapsed and but some collapsed more than others depending on their initial population size and their reproduction potential.
• It seemed that animals ability to recover was also based on their ecology, social behavior, feeding ecology and their ability to move and migrate in search of water and pasture.
• Animal mortality was not only through the lack of critical resources such as water and pasture removed by drought but also on the effect on their physiology through head load, and competition for resources with livestock and man, leading to increased persecution through human wildlife conflicts.
• It is hoped that this study makes a critical baseline reference for the effect of drought on wildlife population, but also gives the population status of wild population recovering from drought effect in the ecosystems bordering northern Tanzanian and southern Kenya between Tsavo parks and Lake Natron.

Kenya/Tanzania borderland is a critical area for conservation of biodiversity. This study was done to establish the effects of 2007 and 2009 droughts through aerial counts. Findings indicate that large mammal population collapsed, but some species crashed more than others. Total large mammal density declined over three times (−207.43%), recovering modestly (+41.59%) between 2010 and 2013. Over that time, the most abundant species was zebra (10,466.3 ± 2860.5 animals), followed by wildebeest (8921.0 ± 4897.9), Grant's gazelle (3447.0 ± 303.7), Maasai giraffe (1381.3 ± 132.7), African elephant (990.67 ± 12.60), eland (544.0 ± 311.4), Thomson's gazelle (495.3 ± 232.3), buffalo (331.3 ± 128.8) and impala (354.3 ± 61.0). The species affected most by drought was lesser kudu, followed by African buffalo, Maasai giraffe, kongoni, common eland, common wildebeest, common zebra, Grant's gazelle, gerenuk, impala, African elephant, Thomson's gazelle and fringe - eared Oryx respectively. Further, large mammal species numbers were dependent on location (χ2 = 13,647.35, df = 15, p < 0.001), with numbers being higher near protected areas. Animals with low numbers, specific diets, water - dependent and limited range were most affected by the drought. This provides a baseline for future comparisons and also future effects of droughts.