Cryptic fecal covering in aardvarks (Orycteropus afer)

In honor of a thrilling nocturnal wildlife sighting, in the middle of an EPIC all-night drive, I want to share my favorite assignment from my semester in southern Kenya at the School for Field Studies. With a few other contenders, it may be my best.titled.paper.ever.

Cryptic fecal covering in aardvark (Orycteropus afer)

Kilimanjaro Bush Camp//Kimana Group Ranch

6 February 2009

7:15 am

Weather Conditions: cool, slightly overcast

Observation: While on a morning nature walk, Daniel and Marias noticed a seemingly freshly manipulated area of dirt. Daniel and Marias began sifting through the dirt and exposed approximately 15 pieces of aardvark dung. They were rounded, smooth and relatively small (4 or 5 pieces were able to be held in Marias’ hand at once). When Daniel and Marias broke open the dung pellets, the interior was relatively dry, consisting mostly of dirt and termite heads. The dung pile was proximate to the opening of a burrow, possibly inhabited.

Hypothesis/Questions:Why would the aardvark work to conceal feces near its burrow opening when several other aspects of its behavior clearly indicate its presence?

Research: Alden et al. (1995) classify the aardvark as nocturnal and solitary. Despite the fact that the aardvark is active predominantly at night, there are several aspects of its behavior which indicate its presence. Stuart and Stuart (1994) describe the aardvark burrow as completely obvious with seemingly little or no effort made to disguise its existence. The entrance of the burrow can be up to 1 meter wide and is evident from surrounding areas (Stuart and Stuart, 1994). The aardvark’s physiology is also such that when it digs it uses its large, strong tail for support, leaving a distinctive marking in the soft dirt (Stuart and Stuart, 1994).

In addition to leaving signs indicating its presence, the aardvark frequently positions its burrow relatively far from its foraging grounds, thereby necessitating a walk each night between the 2 areas (Kingdon, 1997).

The aardvark does, however, simultaneously occupy several “camping holes” which are significantly less developed and more temporary than the full burrow (Kingdon, 1997). While aardvarks tend to generally be solitary, females are often accompanied by 1 to 2 offspring and in some rare cases more than 1 adult has inhabited a single burrow (Kingdon, 1997).

Rather than use feces as a territorial marker, aardvarks secrete a strong musk. Both males and females have glandular areas located on the elbows and hips. Kingdon (1997) suggests that this sophisticated olfactory system most likely regulates the spacing of individuals. Aardvarks make a significant effort to disguise the location of their feces, as they are deposited very near to their active burrow (Stuart and Stuart, 1994). Aardvarks dig a hole prior to defecation, which they fill with as much as 0.5 kg of feces (Shoshani, Goldman& Thewissen, 1988). After completing defecation, the hole is covered. The hole’s position, at a slight incline, makes the feces even more difficult to detect; not only are they covered, but if a predator were to dig vertically it could miss the fecal deposit. Shoshani, Goldman and Thewissen (1988) propose that this behavior contributes to predator avoidance.

Discussion: Despite their relatively obvious burrows, aardvark behavior is generally inconspicuous. Their nocturnal and largely solitary habits greatly reduce their exposure. As an individual aardvark can have several burrow options (a main burrow or one of several “camping burrows”) it may be further able to confuse predators about its specific whereabouts (Kingdon, 1997). As feces do not serve a territorial or larger social role, they remain merely an indicator of presence (Kingdon, 1997). Thus, it is logical for an aardvark to go to significant lengths to conceal its feces. Feces may then be the only temporal and spatially relevant indicator of an aardvark’s location and therefore a considerable danger to its survival.

Conclusion: Although it may seem unnecessary given the very visible nature of the aardvark’s primary habitation, cryptic fecal covering is a behavior of great significance. As feces are one of the few temporal and spatial locators of an individual, it is logical for the aardvark to minimize evidence of its presence as a survival mechanism.

References: Alden, Peter C., Estes, Richard D., Schlitter, Duane, McBride, Bunny. 1995. National Audubon Society Field Guide to African Wildlife. pp. 523-524, Alfred A. Knopf, New York.

Kingdon, Jonathan. 1997. The Kingdon Field Guide to African Mammals. pp. 294-295, A&C Black, London.

Shoshani, Jeheskel, Goldman, Corey A., Thewissen, J.G.M.. 1988, January. Orycteropus after. Mammalian Species, No. 300, 1-8.

Stuart, Chris and Stuart Tilde. 1994. A Field Guide to the Tracks& Signs of Southern and East African Wildlife. pp. 154, 194-195, 244, Southern Book Publishers, Cape Town.