Eremitalpa granti namibensis is a small blind subterranean
insectivore (Chrysochloridae) endemic to the Namib Desert sand
dunes. This study of the biology and ecology of the Namib
mole assesses its adaptive strategies for survival in a harsh
environment. Major areas of study include feeding ecology,
movement patterns, home range, activity, thermoregulation and
water metabolism.
Diet of free-living moles was assessed through stomach content
analysis while qualitative and quantitative descriptions of
surface foraging paths related searching behaviour to resource
abundance and distribution. Moles opportunistically fed on
termites, a sedentary prey resource occurring in patches of
high concentrations while non-random surface locomotion
minimised foraging costs.
Population density and home range utilisation were studied by
following surface trails and capture mark and recapture.
Population density was low but stable and home range size
large. No permanent nests or burrows were found while the
pattern of home range utilisation was nomadic but
circumscribed. Although ranges overlapped, a system of
mutual avoidance limited encounters with neighbouring animals.
Activity phasing was examined in the field and in the
laboratory. Free-living moles were almost exclusively
nocturnal while captive moles were active day and night. These findings are discussed in relation to prey availability,
predator pressure and avoidance of diurnal extremes. Light
and temperature appeared to be important cues for daily onset
and cessation of activity.
Aspects of thermoregulation examined under laboratory and
field conditions revealed high thermal conductance, a low
basal metabolic rate and poor thermoregulatory abilities.
Factors suggested to have selected for these traits are the
gaseous regime of the sand in which moles burrow and the need
to minimise energy expenditure in an energy sparse
environment.
Laboratory and field studies
employing isotopic dilution
of energy and water
methods e xamined the
metabolism
ability of
moles to survive on an insect diet without drinking water.
Water independence was achieved through efficient renal
function while low rates of energy usage and torpor were
further effective in reducing overall water requirements.
In summation, a broad overview of adaptive radiation in Namib
moles compared to other subterranean mammals is discussed. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1989.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/11026 |
| Date | January 1989 |
| Creators | Fielden, Laura Jane. |
| Contributors | Perrin, Michael R. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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