Burrowing and burrow patterns of East African mole‐rats Tachyoryctes, Heliophobius and Heterocephalus

Abstract

With 4 plates and 12 figures)The burrowing behaviour and burrow patterns of the mole-rats Tachyoryctes (Family Rhizomyidae), Heliophobius and Heterocephalus (Family Bathyergidae) were compared. Remarkable similarities were found both in the method of digging and the basic burrow pattern of the three genera. Dissimilarities in burrow length can be attributed to the availability of food and the number of animals occupying one burrow system. Thus, the solitary Tachyoryctes, which eats a wide range of foods, has the shortest burrow system; while the colonial Heterocephalus, which eat a limited range of foods and live in arid regions, have very extensive burrow systems.All the mole-rats bite at the earth face with well developed incisors; collect the excavated soil with their fore and hind feet and push it behind them. Tachyoryctes differs from the bathyergids in then turning round and using one side of its face and one fore foot to push the excavated soil along the burrow and out onto the surface. The bathyergids back up to the soil and push with their hind feet. Tachyoryctes has a multi-purpose nest chamber used for sleeping, food storage and sanitary purposes; the bathyergids have a simple nest chamber used solely for sleeping, they do not store food but instead partly expose tubers in the foraging burrows and eat pieces from them when hungry.Differences between the bathyergids are largely attributable to their social structure; Heliophobius is solitary and Heterocephalus colonial. Digging and soil disposal are essentially similar but in Heterocephalus the various stages are taken by different members of the colony and a digging chain is established. Soil type and moisture content influence mound formation; Heterocephalus kicks out a spray of fine dry soil through an open hole.The other two mole-rats live in areas with higher soil moisture content and push out solid cores of soil.

Burrow architecture of the Damaraland mole-rat (Fukomys damarensis) from South Africa

“…There is evidence to suggest that the Damaraland mole-rats also eat smaller bulbs as husks have been found to be used as nesting material, but no bulbs were present within the burrow system. Bolt-holes were found in four of the burrow systems and appear to be a very common feature in the burrow systems of most species of mole-rat (Schultz, 1978;Jarvis and Sale, 1971;Sichilima et al, 2008;Thomas et al, in review). Bolt-holes have been reported to go to depths of 2m (Davies and Jarvis, 1986) in solitary and social species and up to 3m in the Damaraland mole-rat burrow systems.…”

“…Burrowing in African mole-rats has been described by Genelly (1965) and Jarvis and Sale (1971). The substrate is pushed along the burrow and either pushed to the surface to create a mound or deposited into an old tunnel (Jarvis et al, 1998) depending upon the soil moisture content.…”

Resource characteristics and foraging adaptations in the silvery mole‐rat (Heliophobius argenteocinereus), a solitary Afrotropical bathyergid

“…These are food generalism (Nevo 1999), including consumption of plants that are toxic to other mammals (Bennett and Faulkes 2000), food storing (Nevo 1961), so-called ''geophyte farming'' (Jarvis and Sale 1971;Brett 1991), and arearestricted search (Benedix 1993). Other adaptations, such as kairomone food location (Heth et al 2002;Lange et al 2005) or an increased ability to store body fat expected in solitary species (Burda 1990;Burda et al 2000), are still not well documented in free-ranging subterranean rodents.…”

Pattern of ovulation in the East African root rat (Tachyoryctes splendens) from Tanzania: induced or spontaneous ovulator?

“…The East African root rat is a solitary subterranean rodent belonging to the family Spalacidae (Jarvis and Sale 1971). The root-rat is endemic to East and central Africa with a patchly distribution and particulary restricted to the highland savannah (Katandukila et al 2014;Kokiso and Bekele 2008;Jarvis and Sale 1971).…”

“…The root-rat is endemic to East and central Africa with a patchly distribution and particulary restricted to the highland savannah (Katandukila et al 2014;Kokiso and Bekele 2008;Jarvis and Sale 1971). It is a seasonal breeder possessing two breeding periods per year.…”