If you don't know what you've got...
... how do you know if you've lost it?
(A version of this article was originally published in The Horn, spring 2010. Author: Verity Bowman, Director, Dambari Wildlife Trust)
Zimbabwe’s rhino conservation has for many years been proactive, adaptive and effective with increases in population numbers throughout the country being the envy of several other rhino range states. These gains however are rapidly being stripped away as Zimbabwe’s beleaguered rhino populations face a massive onslaught from poaching. A key component of the anti-poaching effort in Zimbabwe, apart from law enforcement, is close field monitoring of individually identified (ear-notched) rhino and supplementary use of dehorning and telemetry.
Our rhino populations are deliberately scattered around the country in national parks and conservancies, as part of a strategic plan to keep these animals as safe as possible and breeding optimally. Population managers monitor how many rhino they have in their areas, but also need to know who these animals are. After all, if you don’t know what you’ve got, how do you know when you’ve lost it?
For areas with good resources it has been fairly straightforward to monitor marked rhino. However, for properties with limited resources, getting a handle on population size, when not all animals are marked, has been very challenging. For example, one ranger may recognise an unmarked rhino bull that he usually sees next to a dam as Fred, while another calls it George because he sees it some distance away near the kopje. The rhino would be counted twice: a situation that will lead to flawed population estimates.
To minimise these errors, each rhino in Zimbabwe is allocated a permanent, unique national identity number, demarked by ear notching, which facilitates its rapid, confident recognition. Immobilising very young rhino is risky and until it receives its own unique ID (at about two years) a youngster is associated with its mother who has her own ID number. Applying a permanent identifier to “clean” (or unnotched) rhino is a major part of the annual rhino management operations. Rhinos are immobilised and ear notched following the national standardised pattern according to its species and gender. Thereafter, that animal can be unambiguously recognised by trained rhino monitors and patrol staff.
Credit: Dambari Wildlife Trust
In addition to the ear notches, every rhino has subcutaneous microchips (similar to those used on your pets) inserted in standardised positions so that if the animal dies and the ears are missing, the microchips will provide the individual’s identity. Another key management task is dehorning rhino to make them less attractive to poachers. Unfortunately, this doesn’t always work, as ruthless poachers will still kill for the remaining nub of horn.
Radio telemetry is also used to monitor rhino. Advances in technology now allow the smaller rear horn to accommodate the transmitter, facilitating the complete removal of the more desirable (to poachers!) front horn. Telemetry is very useful where rhino live in rugged, inaccessible terrain or whose territory is considered a high risk section of the protected area. Whilst these rhinos may not always be seen by patrols, the telemetry signals indicate their whereabouts and provide assurance that the animals are present.
Knowing who’s who is critical to the overall health and wellbeing of the Zimbabwean rhino population. We can track births and deaths within populations; monitor trends in numbers and sex ratios; and accumulate home range, habitat and behavioural data. Over time we can build life histories of individual rhino that allow us to establish relatedness, inter-calving intervals and determine recruitment rates. This facilitates appropriate adaptive metapopulation management, which ensures that the Zimbabwean rhino population continues to grow at optimum rates. With diligent observation of our identifiable rhino and close field monitoring, we enhance their protection and deter poachers.