African elephants can detect water from natural and artificial sources via olfactory cues

Abstract

Water is vital for mammals. Yet, as ephemeral sources can be difficult to find, it raises the question, how do mammals locate water? Elephants (Loxodonta africana) are water-dependent herbivores that possess exceptional olfactory capabilities, and it has been suggested that they may locate water via smell. However, there is no evidence to support this claim. To explore this, we performed two olfactory choice experiments with semi-tame elephants. In the first, we tested whether elephants could locate water using olfactory cues alone. For this, we used water from two natural dams and a drinking trough utilised by the elephants. Distilled water acted as a control. In the second, we explored whether elephants could detect three key volatile organic compounds (VOCs) commonly associated with water (geosmin, 2-methylisoborneol, and dimethyl sulphide). We found that the elephants could locate water olfactorily, but not the distilled water. Moreover, they were also able to detect the three VOCs associated with water. However, these VOCs were not in the odour profiles of the water sources in our experiments. This suggests that the elephants were either able to detect the unique odour profiles of the different water sources or used other VOCs that they associate with water. Ultimately, our findings indicate that elephants can locate water olfactorily at small spatial scales, but the extent to which they, and other mammals, can detect water over larger scales (e.g. km) remains unclear.

Behavioural hydroregulation protects against acute effects of drought in a dry-skinned ectotherm

“…Behavioural hydroregulation could be controlled by the internal hydration status, leading individuals to choose less desiccating microclimates as a water-saving strategy only when chronically stressed (Ladyman & Bradshaw, 2003;Rozen-Rechels et al, 2020). On the other hand, terrestrial organisms can perceive moisture gradients through hygrosensing (Chown et al, 2011) and further rely on odours or other cues to locate free standing water (Serrano-Rojas & Pašukonis, 2021;Wood et al, 2021), such that changes in air water vapour pressure conditions may also trigger rapid changes in their behaviours.…”

The Olfactory Landscape Concept: A Key Source of Past, Present, and Future Information Driving Animal Movement and Decision-making

“… 2020 ), and abiotic sources such as water (Wood et al. 2021 ), and smoke from fire (Doty et al. 2018 , Mendyk et al.…”

“…Odor has also been shown to be key in locating water (Wood et al. 2021 ), detecting vegetative food quality and toxicity (Brokaw et al. 2021 , Finnerty et al.…”

“… 2020 , Wood et al. 2021 )), threats (predators, competitors, parasites, fire (Poirotte et al. 2017 , Valenta et al.…”

The Chemical Ecology of Elephants: 21st Century Additions to Our Understanding and Future Outlooks

“…Asian elephants can use odor but not sound to locate hidden food [136], and they can assess the quantity of a single food type through olfaction [137]. Recently, African elephants were shown to detect olfactory cues associated with water [138]. The body of work to date suggests that odors play an important role in elephant foraging decisions, but more research is needed.…”