EPOW - Ecology Picture of the Week

Burrow system of an Aardvark (Orycteropus afer), 
Order Tubulidentata, Family Orycteropodidae
South Luangwa National Park, Zambia, Africa

Explanation:   This week you are an aardvark crawling down into your burrow, possibly to escape a predator, here in the lowland woods of South Luangwa National Park in eastern Zambia, Africa.   

Notice the multiple burrow entrances, which may be a strategy to thwart predators and avoid getting trapped in the tunnels.  Aardvarks create extensive burrow systems, with several burrows at once in an area. This too may be to confuse predators.

Aardvarks are sturdily built with massive digging forelimbs.  Other common names of aardvarks are "ant bears" and "earth pigs," apt descriptions of their unusual appearance and habit of digging burrows.  They are noctural, active at night, so we humans typically see lots more of their burrow activities than the animals themselves.

Aardvarks move a lot of dirt when they excavate their burrows.  This is one of their "key ecological functions," to turn over soil.  

Look deep into the heart of this burrow --- there is a small visitor, a millipede.  In fact, that is another ecological function of aardvarks.  Their burrows are often occupied by many other creatures.   

Aardvarks have been exterminated in many agricultural areas because their burrows are inconvenient or dangerous to vehicles, livestock, and water dams. Their extirpation has extensive side-effects because aardvark holes are extremely important as refuges for many species of small mammals, including bats and carnivores, reptiles, invertebrates, and birds.

 
Aardvark burrow, Nyika Plateau National Park,
northern Malawi, Africa

Their (assumedly vacant or abandoned) burrows are used diurnally by warthogs (Phacochoerus aethiopicus).  Both warthogs and aardvarks churn up and dig through soil, the former for food and roots, the latter for burrows, temporary dens, and food.  Both likely serve to help improve soil structure (increasing friability) and incorporate organic material into the soil. Warthogs can also dig their own burrows (as "primary burrow excavators") but generally prefer the lazy way of occupying burrows dug by other animals (as "secondary burrow users"), principally aardvarks.  

Spotted hyenas (Crocuta crocuta) also will secondarily occupy aardvark burrows.

Aardvarks move a LOT of soil!
Aardvark burrow, Zimbabwe, Africa.

Another key ecological function of aardvarks is dispersal of plant seeds.  In Africa, the aardvark digs into soil and extracts and consumes a large seed pod of a melon plant, and then disperses the seeds through its droppings. The aardvark may be an obligate dispersal agent for this plant. 

At least one African tribe, the Bamana of Mali, perform dances to celebrate their farming which was supposedly taught to them by a mythical entity Chiwara, with the dance movements emulating antelopes and the burrowing aardvark.

In the final part of this story, aardvarks often burrow into the base of termite mounds.  Thus, there is quite a chain of dependency that occurs in these wildlife communities.  Termites build mounds, which can also support the growth of plants; aardvarks burrow into the mounds, turning over soil that improves habitats for plants and soil insects, and disperse viable plant seeds by their dung; and then many other animals secondarily use the aardvark burrows.  And then ecologists photograph the burrows and show them to you!

Left: Aardvark burrow dug into the base of a large ground termite mound.  
Lengwe National Park, southern Malawi, Africa.  

About Today's Photo:  I created today's EPOW main photo by animating a series of individual digital photos I took in South Luangwa National Park in Zambia, Africa.  I squeezed head-first into the pitch-dark burrow, happy not to unexpectedly encounter angry hyenas, venomous snakes, or other startled predators.

Information:  Kingdon, J. 1997. The Kingdon field guide to African mammals. Academic Press, San Diego. 464 pp.