Saved by the Smell: Using Chemical Signals to Protect Predators and Livestock

ABSTRACT

Botswana Predator Conservation’s BioBoundary Project is developing new ways of

mitigating human-predator conflict, by using artificial equivalents of the predators’

chemical signals to keep them away from livestock, or safely inside protected wildlife

areas https://www.bpctrust.org/project/bio-boundary-project/ .

To produce artificial chemical signals, we need to know the composition of the real

ones, and which of the hundreds of compounds that make up mammal odours are

actually sending the messages we need to replicate,

GC-MS analysis very quickly yields long lists of components, but no hint as to which of

them are biologically relevant. Taking a reverse engineering approach and looking for

compounds that fit the specifications for a long-lasting, stable signal can provide some

clues; for example, two sets of lactone stereoisomers in African wild dog urine would fit

the design criteria for a stable, long-lived multi-component chemical signal.

Another approach is to compare materials that send chemical signals with those that

do not – but that depends on a detailed understanding of what is a scent mark and

what isn’t. The discovery in 2015 that African wild dogs communicate with their

neighbours by scent marking at specific repeatedly-used sites was a breakthrough in

our understanding of what qualified as a wild dog scent mark. However, it meant that

our previous analyses of faeces and urine collected without reference to locality – and

so, as far as we can tell with hindsight, mostly not from marking sites and not containing

messenger compounds, all need to be done again with samples collected specifically

form marking sites.

The third approach is to test scent components individually or in simple mixtures to see

what the animals respond to. That needs animals and the chemical signals to defy the

orthodox view that mammal chemical signals are all complex mixtures, and that is

exactly what we see; using a combination of controlled release odour dispensers and

camera trapping we record single components and simple mixtures eliciting the intense

sniffing and scent marking which would be expected in response to natural scent

marks. Some of them also repel predators, including leopards, spotted hyaenas, blackbacked

jackals and caracals, which are the four most serious livestock killers. These

repellent effects will allow us to mitigate human-predator conflict by keeping predators

away from livestock with chemical “no trespassing” signs.