Potential amplification of territorial advertisement markings by black-backed jackals (Canis mesomelas)

AbstractOptimality theory suggests that territorial scent marks are under selective pressure through the information they provide about competitive quality/reproductive status and so should be situated to maximize their detection to alert conspecifics that they are intruding upon the territory of a resident. Factors that increase mark detectability are consequently beneficial to both resident and intruder by allowing tactical withdrawal by intruders and, thus, reducing the costs of conflict. We tested whether black-backed jackals (Canis mesomelas) preferentially deposited territory marks on substrates (rocks or faeces) in two separate sites in South Africa's Addo Elephant National Park. Elephant (Loxodonta africana) dung piles were preferentially defecated upon by jackals in both sites. Where black rhinoceros (Diceros bicornis) was present at relatively high density, rhino middens were also preferentially marked by jackals; however, jackals resorted to defecating on elevated surfaces, such as rocks, where rhinos were scarce. We hypothesize that the odour of elephant and rhino dung may increase the detectability of jackal markings while providing an additional olfactory signal component, while rocks and elephant dung provide visual amplification. Manipulative experimentation will be necessary to confirm our multimodal amplification hypothesis.