New Publication: Horse tails and Oyrx horns- Novel attachments for tracking mammals

Way back in 2017, while working at the Smithsonian Conservation Biology Institute (SCBI) I was working on a trial of some dummy tracking units to see if we could successfully attach them to the tails of horses. That work progressed from using dummy tags to a full trial of working devices and novel attachment methods. We recently published the results in a new paper. It has taken a few years and a lot of work with my fantastic co-authors (particularly Katherine Mertes and Catherine Ressijac) to get this one across the line and it’s great that it is finally out there in the world.

As tracking technology has rapidly advanced in the last few decades devices available to researchers have been getting smaller and lighter every year. However, when tracking medium to large terrestrial mammals, collars are still the most common choice. They are selected because we know they work and have limited impacts on welfare. There are scenarios where a collar just won’t do the job due to the behaviour of the animal or their age.

Teams at SCBI and partner organisations have been working for decades to protect and study Przewalski’s horse (Equus ferus przewalski) and Scimitar-horned oryx (Oryx dammah) and to reintroduce them to their natural ranges in Mongolia and Chad respectively.  Both conservation initiatives could benefit from additional tracking approaches that expand the collection of movement data to life stages that are currently unobservable.

Przelwalski's horses in Mongolia. Collared female on the right. Uncollarable male on the left.

The Przewalski's horse was previously extinct in the wild but now exists in 5 sub-populations across Mongolia and China (Kaczensky et al. 2011, King et al. 2015). We know we can successfully collar Female Przewalski's horses, but stallions grow rapidly and fight intensely during the mating season, often biting around the head and neck. As a result, bachelor Przewalski's horses (groups of sub‐adult or sub‐dominant males not associated with female harems) have not been observed extensively in the wild, and their movements remain almost entirely unknown.

The scimitar‐horned oryx was downlisted from extinct in the wild to endangered in 2023 because of ongoing conservation efforts in Tunisia, Morocco, and especially Chad. Most oryx (>90%) reintroduced into Chad are fitted with a GNSS or satellite collar (Mertes et al. 2019).

However, many subadult oryx suitable for reintroduction would quickly outgrow even an expandable collar, and fighting between adult male oryx has led to the loss and malfunction of collars.

We were lucky enough to have a captive population of both species right in our back yard in Virginia as part of their breeding programs. We tested 6 prototype solar‐powered, global navigation satellite system (GNSS) tracking scimitar‐horned oryx and Przewalski's horse with devices attached to horns and tails, respectively. We assessed device performance as well as potential physiological and behavioural effects of these alternative attachments of tracking devices.

Tracking devices attached to a female scimitar-horned oryx under human care (A); a male Przewalski's horse under human care (B); a female oryx released in central Chad that carried a dummy horn-mounted tag attached using adhesive for 3.5 years (C); and a male oryx released in November 2024 carrying a functional horn-mounted tag attached using adhesive (D).

Our novel attachment methods achieved fix success rates and spatial accuracy comparable with standard collar attachments used on large terrestrial mammals. The presence of a device did not significantly predict behavioural or physiological stress for either species. Solar panels were able to maintain charge throughout the test period.

While a later modification substantially improved deployment length, attachment durability remains a key area for improvement. We urge ecologists and conservation practitioners to consider the full range of tracking devices and attachment methods available from tracking technology manufacturers, assess whether alternative attachments could achieve scientific or conservation objectives with reduced impacts on study species, and carefully test any tracking device before long‐term deployment. To read more see the full paper here.

Views and opinions expressed in this research blog are my own and do not represent those of my current or past employers in any way