The stench of compatibility: How otters identify one another, and potential mates by smelling their poop

Otters don’t tend to be very visible to us, but they are more abundant than we might perceive them to be. Otters mostly live in isolation of one another, yet they manage to remotely communicate to one another.

On this blog, I previously wrote how otters communicate with one another using their spraints (faeces). They use them to mark their territory and to leave messages for other otters. As part of the research project I work on, we collect these spraints for DNA analysis to tell us about the population.

When we find a suspected otter spraint, we often smell it as otter spraints have a distinctive smell that isn’t all that dissimilar to jasmine tea! But there are more sophisticated methods that can be used to better understand the chemical cues and cryptic messages held within a spraint.

otter b. fennessey (3)

A new study by Eleanor Keane and colleagues at Cardiff University, published in Mammalian Biology has sought to understand some of these chemical messages.  Keane explains in their study that “otters have two anal sacs, each of which deposits secretions with faeces (spraints)”.

Keane visited a number of wildlife centres in the UK, Germany and Spain to collect spraints from captive otters to investigate if otter spraints contained individually unique signatures in the volatile organic compounds found their anal gland secretions.

Otter spraint on a little grassy tussock

Otter spraint on a little grassy tussock

Using chemical analysis, Kean et al. discovered that there were over 160 compounds commonly found in the otter spraints. When Kean et al. statistically analysed the results, they found that over 40% of the variation could be explained by individual identity, i.e. spraints contained a unique assemblage of chemical compounds that could be used by otters to identify each other.

Kean suspects that the remainder of the variation might contain other messages that were not assessed in this current study such as the sex of the individual, age, reproductive status, the length of time the spraint was deposited, and possibly even the health of the animal. It may also be possible that otters can useuse to tell if they are related to a particular animal, just by smelling their spraint!

However, Kean et al. believe that this method will not be useful for population estimates of otters as each spraint, even those that originate from the same individual can contain a different assemblage of compounds. So in the meantime, it looks like DNA analysis may still the most suitable method for population studies of otters.


Kean, E., Chadwick, E., & Müller, C. (2014). Scent signals individual identity and country of origin in otters Mammalian Biology – Zeitschrift für Säugetierkunde DOI: 10.1016/j.mambio.2014.12.004

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