Unique Stripe Patterns
Just like humans have unique fingerprints, Grevy’s zebra have unique stripe patterns and that is how we identify individuals within a population. Over time, this provides us with vital information on survival, reproduction and movements of Grevy’s zebra.
The Grevy’s Zebra Trust uses this method to intensively monitor Grevy’s zebra in the Wamba Region across the community conservancies of Kalama, Meibae and Westgate. Each month we conduct photographic surveys along predetermined routes, capturing all Grevy’s zebra encountered.
Members of the Grevy's Zebra Technical Committee have established a centralised database where each member contributes their photographs and associated life history information. Over time, the database will provide critical information for planning future conservation action.
The History of Stripe Recognition
The first people to develop this system were Hans and Ute Klingel in the 1960s. They would take photographs of the left side of Grevy’s zebra. They constructed their own dark room while out in the bush and developed several hundred rolls of films during any one field excursion. They then developed file cards for each zebra identified and would code the stripes. Using this unique coding system they were able to know which zebras they had seen for the first time and which they had “re-captured” in their camera lens.
With the development of the computer age, researchers began using computer programmes to identify Grevy’s zebra, but there were technical problems: the stripe pattern had to be coded by eye, which carried the risk of variation in interpretation through different observers. The code then had to be entered by hand, adding another layer of risk through typing errors. Additional information had to be entered into a separate database.
Digital Identification Software
The concept of a computer based program which individually identifies Grevy’s zebra by their unique stripe patterns was borne following discussions between Princeton University and Marwell Wildlife . Such a system would automatically compare photos of individuals to a database of previously recorded animals, thus saving researchers in the field weeks of manual work. It soon emerged that a system like this already existed, and was in the early stages of development with Conservation Research Ltd.
The stripe ID software uses a 3-dimensional model to fit a generic body shape to the photo. In the case of Grevy’s zebra the system applies the model of a zebra to the photo and takes into account the different positions of the animal. Posture and fattening & thinning of the animal (e.g. during pregnancy) are accounted for.