Okavango Delta Management Plan - Ramsar Convention on Wetlands

Seventeen range-restricted or biome-restricted species occur in the <strong>Okavango</strong>. One of these,
the Chirping Cisticola is aquatic, and in Botswana is confined to the <strong>Okavango</strong>. The others
are more widespread, and most are common in their respective habitats.
Following the criteria laid down by BirdLife International, the <strong>Okavango</strong> <strong>Delta</strong> is also of
conservation importance for a substantial number of congregatory waterbirds; it supports
over 1% of the global populations of 20 species, and 0,5% of the global populations of
another 12 species.
The vast majority of the birds found in the <strong>Okavango</strong> <strong>Delta</strong> are breeding residents, 339 or
76%. There is, however, a significant number of avourable migrants all of which are
waders (29 %), that visit the <strong>Okavango</strong> specifically because of its wetland habitats.
2.3.3.5 Mammals
The <strong>Okavango</strong> <strong>Delta</strong> has a wide variety of large mammals occurring locally in high
numbers, and which are the main attractions in the growing tourism industry (Mbaiwa,
2003). However, most mammals in the <strong>Delta</strong> are fairly small and often overlooked. The
overall mammal biodiversity of this entire community is determined by such factors as
habitat diversity, connectivity to species pools in the Southern African region and the
environmental history of the <strong>Delta</strong>.
Number of species
Some 122 mammal species of 12 orders and 34 families live in the <strong>Okavango</strong> <strong>Delta</strong> (Table
15). All the larger species are wide spread across the African Savanna region. The
distributional ranges of some of the larger mammals are marginally within the <strong>Delta</strong> but
occur in the larger <strong>Ramsar</strong> site. One of these, the Sable Antelope (Hippotragus niger), is
common in the broad-leaved woodlands and the grasslands close to the <strong>Delta</strong> (Skinner &
Smithers 1990). Similarly, the Eland (Taurotragus oryx) and the Gemsbock (Oryx avoura)
prefer drier landscapes and rarely spend time in the <strong>Delta</strong> (Skinner and Smithers 1990).
The Black Rhino (Diceros bicornis) and the White Rhino (Ceratotherium simum) were driven
to extinction in the <strong>Delta</strong> and Linyanti by poachers 20-30 years ago. The latter species has
recently been re-introduced.
Species composition and size distribution
Almost half of the mammal species are bats or rodents (n=57). Most of these are small and
weigh less than 100 g. A third of the mammals (n=40 species) are heavier than 10 kg and
11 of these are carnivores. At least 18 species weigh more than 100 kg. These include the
large African antelopes, the Burchell’s Zebra (Equus burchelli) and the African Lion
(Panthera leo). The four species that are heavier than 1000 kg include the White
Rhinoceros, the Hippopotamus, the Giraffe (Giraffa camelopardalis), and the African
elephant.
The two most common of these megaherbivores (Owen-Smith, 1988) significantly affect the
physical environment. Elephants that feed on a large variety of plants, including trees and
shrubs, modify the terrestrial habitats of other species in the <strong>Delta</strong> (e.g. Gilson and
Lindsay, 2003), for instance by changing woodlands to grasslands. Hippopotami on the
other hand, change both the aquatic and floodplain habitats for species living in the <strong>Delta</strong>
(McCarthy et. Al. 1998) by opening up channels and facilitating flooding.
Common species and total biomass
The Impala is the most common large mammal in the <strong>Delta</strong> (Table 2-5), followed by the
Buffalo and the Red Lechwe (Bonyongo, 2004). Elephants are also very abundant. This
species has increased in numbers from 2300 (1975/76), to 5700 (1984/85) (SMEC, 1989),
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