THANK YOU to all those who participated in the Great Grevy's Rally in 2016!
Performing the census required an enormous effort since Grevy’s zebras range over 25,000 km2. It was solved by involving the general public. The area was divided into 45 blocks and teams comprised of over 350 members of the public, conservancy members, rangers and scouts from conservancies and National Parks and Reserves, government officials from the counties as well as KWS and academic scientists. These volunteers spent two consecutive days between January 30 – 31, 2016 driving around each counting block photographing as many Grevy’s zebras as possible. Their goal was to record every Grevy’s Zebras they encountered on their allocated block and take identifying pictures of the unique identifying stripes of each and every Zebra they saw. Moreover, each photograph included data on the date, time of day and geolocation, which pinpoints their location in space and time.
The teams took over 40,000 images! These images were submitted to the IBEIS/WILDBOOK hotspotter team at Princeton University for analysis. The number of pictures submitted to the Princeton team was much higher than anticipated, so new computer algorithms had to be developed to handle such ‘big data’. 15,246 images were crisp and clear and had Grevy’s zebras facing in the right direction. Those photos generated 16,866 images of individual zebras and the hotspotter analysis yielded 1,942 uniquely identified and named individuals.
From this data, and extrapolations for other areas that were inaccessible or too dangerous to survey during the census period, three major findings emerge.
1. The estimate of the size of the national Grevy’s Zebra population is 2,350, with a low of 2,257 to a high of 2,443.
2. The demographic state of the national population and most counties are healthy.
3. The reproductive potential of the population is strong and steady.
The results were released on the 3rd of September at the Great Grevy's Ball at the Mount Kenya Safari Club in Nanyuki. Through the Great Grevy's Ball, we celebrated one of the largest citizen science efforts in Kenya. We also celebrate a spectacular icon and national heritage of Kenya- the Grevy's zebra. You can download the full report here.