Good News for Grevy’s


By Zoe Sims

Citizen science census shows growth in endangered Grevy’s Zebra populations, registers a starting point for threatened Reticulated Giraffe recovery


After months of analyses, the results of the second-ever Great Grevy’s Rally are in, and the news for the endangered Grevy's Zebra is good.


Thousands of photos collected by hundreds of citizen scientists this January have been synthesized into an updated estimate of the Grevy’s Zebra population size and status: there are just over 2,800 Grevy’s Zebra in northern Kenya, reflecting a significant increase compared to the 2016 estimate.


The 2016 Great Grevy's Rally was the first-ever citizen science ground census of the Grevy's Zebra in Kenya. In January 2018, the census was repeated at an even larger scale, including an additional species (the Reticulated Giraffe), and involving citizen scientists and schoolchildren from across the country.


Over two sunny late-January days, at least 700 people, including 212 armed with digital cameras, collected more than 49,000 photos of Grevy’s Zebras and Reticulated Giraffes as they traversed the animals’ range in Laikipia, Samburu, Meru, Isiolo and Marsabit counties. After the Rally, a computer program scanned these images to detect the distinctive stripes of a Grevy's Zebra or the tiles of a Reticulated Giraffe. This information was then analyzed, databased, and compared to determine the identity of each photographed individual. 

Below right, students from local primary schools, some of the youngest citizen scientists, participate in an exercise about Grevy's Zebra biology and conservation while out in the field.

After two years of severe drought, an increase in livestock populations, and new disease outbreaks in northern Kenya, the 2018 re-survey provided a critical reassessment of the endangered Grevy's Zebra population.


The census results show the Grevy's Zebra population has risen from 2,350 individuals in 2016 to 2,812 individuals as of the January 2018 census. The largest increases were registered in Marsabit and Isiolo Counties, where an increased citizen-science effort on the ground significantly increased zebra sighting records. The largest proportion of the Grevy’s population remains in Laikipia County, where over 800 individuals are found between three conservancies alone (Ol Jogi, Loisaba, and Mpala). 

The researchers also found that the Grevy’s population of infant and juvenile zebras has declined in the last two years. A growing, healthy population has a high proportion (> 30% of individuals) of infants and juveniles, and this was true of the Grevy’s Zebra population in the 2016 census. These young zebras represent the population’s future. In 2018, however, the proportion of infants and juveniles had significantly dropped across the Grevy's range. 

Yet the Rally scientists also find cause for optimism in these statistics. In the past two years, while the savanna was dry and grass was scarce, many zebras skipped a breeding season. However, after several months of heavy rains, Savanna conditions have changed in favour of the Grevy's, and their potential offspring. The Grevy’s Rally scientific team estimates that, after skipping a year, the zebras are now ready to reproduce in an environment that is ideal to support new young. 

Abovegraph illustrating the Grevy's Zebra population estimates in 2016 and 2018 in Kenya and multiple counties. 


Reticulated giraffe, which were recently listed as "threatened" by the IUCN, were included in the 2018 census for the first time. The subspecies, which inhabits similar habitats to the Grevy’s Zebra, has even lower numbers than the Grevy’s, with a total population size estimated at 2,309 individuals. Conservation-minded citizens, remember that number: with the census scheduled to be held again in 2020, we will be able to track the giraffes’ status and progress alongside the Grevy’s over the next two years. 

The census was possible thanks to the support of citizen scientists and conservancies, counties, and KWS staff from across Kenya. The Kenyan government and particularly the Kenya Wildlife Service were key to the Rally’s success, along with research support from Princeton University, Rensselaer Polytechnic Institute, and the University of Illinois-Chicago, with funding and in-kind support from a wide collaboration of organizations and conservancies, including the Mpala Research Centre, Northern Rangeland Trust, Lewa Conservancy, Grevy’s Zebra Trust, WildlifeDirect, Giraffe Conservation Foundation, Laikipia Wildlife Forum, Saruni, Fairmont’s Mt. Kenya Safari Club, Laikipia and Samburu Counties, Theodora D. and William H. Walton, III Family Foundation, the US National Science Foundation, Microsoft, the Saint Louis Zoo, the Marwell Zoo, the San Diego Zoo, WildMe, Pineapple Fund, Amazon Web Services, and NVIDIA.

The full official survey results were presented at the Great Grevy’s Ball in  Nanyuki, on Saturday, June 23rd 2018, to Dr. Samuel Kasiki, the KWS Deputy  Director for Biodiversity, Research and Monitoring, and Dr. Patrick Omondi, the Deputy Cabinet Secretary for Wildlife and Tourism, for their ongoing use in management of the landscape and the species. 

Mpala and the Great Grevy’s Rally team look forward to welcoming even more participants in 2020 to count what we hope will be even larger populations of Grevy’s Zebras and Reticulated Giraffes!


Above leftDr. Dan Rubenstein presenting during the Great Grevy's Ball 


All census results and analysis is derived from the Great Grevy’s Rally Report:

The Great Grevy’s Rally (2018). The State of Kenya’s Grevy’s Zebras and Reticulated Giraffes: Results of the Great Grevy’s Rally 2018. Rubenstein, D., Parham, J., Stewart, C., Berger-Wolf, T., Holmberg, J., Crall, J., Low Mackey, B., Funnel, S., Cockerill, K., Davidson, Z., Mate, L., Nzomo, C., Warungu, R., Martins, D., Ontita, V., Omulupi, J., Weston, J., Anyona, G., Chege, G., Kimiti, D., Tombak, K., Gersick, A., & Rubenstein, N.