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Examining owl vomit

Published 10 Feb 2020 by Eliza Herbert

While the idea of trawling through owl vomit might be nausea-inducing for some (picture skeletal remains, fur and feathers), for our senior ecologist Dr Alex Kutt it’s a clever way to find out more about the secrets of the land.

You might remember from one of Alex’s previous blogs that owl ‘pellets’ – undigested and regurgitated nuggets of fur, bone, feathers and scales – can provide valuable data on current or historical changes in mammal fauna over time and can even teach us more about cryptic or threatened species.

In a study on our Cravens Peak Reserve in western Queensland, Alex and a team of ecologists (including Bush Heritage’s Dr Pippa Kern) took to the field to collect 125 Eastern Barn Owl pellets from a well-known roost called the ‘Bat-hole’ – picture Batman, Catwoman and their team taking to the Batmobile to fight conservation crimes with owl vomit.

Those crimes were eating cute things; the punishment? Coughing up the evidence.

Craven’s Peak is big ­– 233,000 hectares to be exact (roughly the equivalent of 116,500 MCGs side by side) – and so monitoring the animals that live there can pose quite a challenge. Located on the boundary of the Simpson Desert, Cravens Peaks is dry and full of open dune fields dominated by spinifex, floodplains and coolabah-lined channels, wetlands and swales and grasslands and shrublands.

It's also an oasis for many native animals, largely mammalian owl snacks, like the nationally vulnerable Mulgara, hopping mice, False Antichinus and a range of other rodents and marsupials. Oh and of course the most diverse reptile community in Australia.

Barn Owls are significant and wide-spread native predators in Australia that can fly over 10km from their roosts to hunt.

While native avian predators play an essential role in maintaining balance in our ecosystems, they can also prey on species of conservation concern, with about 90% of the Eastern Barn Owl’s diet comprised of small mammals.

Alex and colleagues from the Queensland University of Technology sent their owl pellets to the Queensland University of Technology and Queensland Museum for analysis.

From the 125 pellets, 642 individual animals were identified, including 24 invertebrates, five birds, 15 reptiles and 595 mammals.

One of those mammals was the Dusky Hopping-mouse (Notomys cf. fuscus), which is the northern-most record for the vulnerable species and the first in the region since 1972.

By using pellet age as a proxy, they also found that different species/prey groupings were common to different time periods, suggesting that changes in the rainfall driven arid desert system over time can lead to changes in mammal populations and that owl vomit can be a tool to monitor which species occurred at which times and in what areas.

Importantly, their findings also suggest that these little nuggets of ecological goodness can be very useful when accurately reporting on the condition and trend of landscapes managed for conservation. 

Who knew owl vomit could be so valuable?

Barn Owl at Cravens Peak Reserve. Photo Jane Blackwood. Barn Owl at Cravens Peak Reserve. Photo Jane Blackwood.
Pellets of owl vomit (spit/pellets) collected for analysis. Photo Pippa Kern. Pellets of owl vomit (spit/pellets) collected for analysis. Photo Pippa Kern.
Dr Alex Kutt collecting specimens. Photo Pippa Kern. Dr Alex Kutt collecting specimens. Photo Pippa Kern.
The 'Bat Cave'. The 'Bat Cave'.
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