Bernardos Blog: Aardvark Den

Aardvarks, Orycteropus afer (Pallas, 1766) are medium-sized (40-70 kg), nocturnal mammals that are found in a wide range of habitats across South Africa (Smithers 1990; Stuart 2001). Soil type is known to influence aardvark distribution as they are semi-fossorial and need to excavate burrows for food and shelter (Smithers 1971; Melton 1976; Van Aarde et al. 1992; Whittington-Jones et al. 2011). Aardvarks are known to excavate two types of holes (Whittington-Jones et al. 2011). Shallow holes are excavated in termitaria or open ground when searching for food, and much larger, deeper holes (or burrows) are excavated for shelter and/or protection (Whittington-Jones et al. 2011).

Aardvarks are considered a keystone species in grasslands as their burrows create a micro-habitat which facilitates the existence of many other vertebrate species (Cilliers 2002). As many as 39 (25 mammals, 7 birds, 6 reptiles and one amphibian) nocturnal and diurnal species have been recorded to make use of aardvark burrows for short or long-term shelter and as a place to rear their young (Smithers 1971; Whittington-Jones 2006).

Despite their importance in a range of different ecosystems, aardvarks remain poorly studied and it is crucial that we gain an understanding about this elusive animal’s ecology as a loss of this species may have cascading effects in various ecosystems.

Aardvarks have very poor eyesight but a highly developed sense of smell (Melton 1976; Skinner 2000; Stuart 2001; Skinner 2001). Both male and female aardvarks possess a scent gland that resembles a scrotum (Kingdon 1997). These scent glands produce a strong musk-like odour which the aardvarks use to indicate their presence in an area by scent marking the soil (Kingdon 1997). This indicates that they may be territorial although this, as well as the chemical composition of their scent, has never been studied. Social interactions between these solitary animals have rarely been observed, particularly amongst males, and consequently are poorly understood.

Their highly developed sense of smell is also of particular importance when finding food (Melton 1976; Skinner 2000; Stuart 2001; Skinner 2001). The abundance and distribution of their prey has been identified as one of the most important factors affecting aardvark populations. Aardvarks are myrmecophagous and most previous studies found them to feed predominately on ants in the dry season and termites in the wet season (Smithers 1971; Melton 1976; Wilson 1979; Daniels 1986; Willis et al. 1992; Stuart 2001). However, Taylor et al. (2002) found no clear seasonal variation in prey selection. Aardvarks may cover large distances searching for food and once an ant or termite colony has been located, they use their massive front claws to rip open the colony (Skinner 2000; Stuart 2001; Skinner 2001). They then use their long, sticky tongues to search for insects (Stuart 2001). Although their diet consists mostly of ants and termites, aardvarks are known to occasionally feed on other insects (e.g. grasshoppers and beetles) and the fruit of the wild ‘aardvark-cucumber’, Cucumis humifructus (Meeuse 1963; Kingdon 1997; Stuart 2001). While diet composition has been studied in the Karoo (Van Aarde et al. 1992; Taylor et al. 2002), these studies are lacking in grassland ecosystems.

Aardvarks are classified as ‘Least Concern’ (Lindsey et al. 2008) however their population numbers may be overestimated due to their reclusive nature and uncommon sightings. Despite popular belief, population numbers cannot be estimated from the number of burrows as aardvarks change burrows frequently and an area may contain many abandoned burrows.

Dr. Amy-Leigh Shuttleworth (nee Wilson), 2014