Counting a regional population of any animal is often an expensive and time-consuming business for any conservation organisation. Ground counts simply cannot cover a large enough area, and aerial counts can lead to inaccuracies. This is the challenge the Grevy's Zebra Trust faced in northern Kenya. Grevy’s zebra numbers have been declining over the last 30 years, but recent counts and censuses have been fraught with difficulties and as a result, the size of Kenya’s Grevy’s population is only vaguely known.
To tackle this, the Grevy's Zebra Trust teamed up with the Northern Rangelands Trust, Laikipia Wildlife Forum, Princeton University, Lewa Wildlife Conservancy and 5 county governments to organise the first ever citizen-driven census of an endangered species in Kenya. In January 2016, more than 120 teams of citizens joined together with community conservancy staff, county officials, scientists, and diplomats. Each was allocated a block in either Laikipia, Meru, Isiolo, Samburu or Marsabit county, and armed with a GPS camera. More than 40,000 images of Grevy's zebra were taken across 25,000 square kilometres over 2 days.
As Ol Pejeta is home to a small population of Grevy's, and our Ecological Monitoring Team know exactly how many are in the Conservancy, we were not included in the Rally block allocations. However, with a collective interest in the conservation of an endangered species, we still followed the count closely, and eagerly awaited the results.
The photographs were sent to the US-based IBEIS team to process. This team was able to use a stripe-recognition software to identify and catalogue individual zebra - with gender, location and approximate age. The conclusion? Kenya’s Grevy’s zebra population is 2,350 individuals. This took into account around 100 animals that occur in small areas outside of the Grevy’s zebra’s historical range, and in areas that were too dangerous or inaccessible to survey during the census period.
Historically, Laikipia County was not a natural part of Grevy’s zebra range. However, results showed that Laikipia, in which Ol Pejeta is situated, has the highest number of Grevy's zebra of all 5 counties in the census. It is thought that the Laikipia's healthy rangelands are now better suited to supporting herbivores - and tells us that the Grevy’s zebra is a sensitive and reliable indicator of landscape and ecosystem health.
As much as the data gathered raises new questions about the status, health and future of the Grevy’s zebras, it will also enable conservation organisations to work together on more targeted conservation strategies. Ol Pejeta hopes to continue working with neighbouring communities and land owners to protect and grown Grevy populations.