Burrows, surface movement, and swimming of Tachyoryctes splendens (Rodentia: Rhizomyidae) during flood conditions in Kenya



The effect of flooding on the behaviour of most mammals has not been studied, even though in tropical areas there are well delineated wet and dry seasons which produce flood conditions on a regular basis. Fossorial mammals can be expected to be particularly vulnerable to flooding because of the absolute dependence on a sub-surface existence and poor climbing ability.

Behaviour of the East-African mole-rat, Tachyoryctes splendens, was studied under flood conditions and compared with published field work conducted under non-flood conditions. Four completely excavated burrow systems were obviously abbreviated (2–9 m in length), although the nest area did not appear to be affected. Live-trapped animals released on the surface travelled as far as 80 m before attempting to dig; surface speed was generally slow (7 m/min). Animals generally (83% of the trials) excavated towards the increase in slope on the study area; total digging time before closure of the tunnel ranged from 7–49 min. In swimming trials, animals were not hesitant to enter water but swimming endurance was short (range 115-550s).

Flooding may be a very disruptive but not an entirely negative aspect of the biology of Tachyoryctes. Dispersal may be instigated and even assisted by providing surface routes over edaphic barriers and moist soils which are readily workable.