Can the potential for tick infestation influence patterns of resource use by Eland (Taurotragus oryx)?
Date
2016-05-10
Authors
McCulloch, Douglas John
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Abstract
The vegetation of the Kgaswane Mountain Reserve, in North West Province, South Africa,
was mapped according to seven vegetation structure types, based on tree density and height,
and grass height. Free-living ticks were collected by drag-sampling the vegetation from each
structure type in November 2014, prior to the onset of the summer rains, and February 2015,
once most of the seasonal rains had fallen. Eland (Taurotragus oryx) location information
was recorded from four GPS collared cows over the two sample periods. Tick abundance was
consistently lower in shorter, open, more exposed vegetation structure types, and higher in
more sheltered types. Position higher up in the landscape nullified the positive impacts of
trees on beneath-canopy microclimate in tall open woodlands, as indicated by comparatively
lower tick numbers than in more sheltered woodland types. Tick abundance is influenced by
vegetation structure and the availability of hosts. The majority of ticks trapped during both
periods were larvae, with nymphs mostly present in November and adults mostly present later
in the season, indicating the seasonal nature of tick cohort recruitment. Eland calving
behaviour centred on areas with low adult tick abundance. Eland did not respond to total tick
abundance during either sampling period. They did select areas with low adult tick
abundance, and avoided areas with high adult tick abundance. This corresponded with an
improvement in upland forage quality, which allowed them to avoid foraging in areas with
high adult tick abundance. It is plausible that the potential for infestation by adult ticks may
be a supplementary influence driving the use of space by eland.
Description
A research report submitted to the Faculty of Science, University of Witwatersrand, in partial
fulfilment of the requirements for the degree of Master of Science (Resource Conservation
Biology).
Johannesburg, 2015