Giraffe productivity and calf survival in a savannah area outside an east African protected area: Implications for conservation

Abstract

Protection of nursery areas where newborn survival is successful is critical to recovery of endangered mammals. In Kenya, 2014 to 2022, we surveyed Endangered Masai giraffes (Giraffa camelopardalis tippelskirchi) on the Siria Plateau at Oloirien Group Ranch (OGR) and Oloisukut Conservancy (OC), and in the Rift Valley's Mara Triangle Conservancy (MTC). MTC and OC have high lion densities while OGR does not. Using counts and photographic mark-recapture (PMR), we estimated percentages of newborn (<3 months) and juvenile giraffe calves (<1 year) per adult female and per total giraffes sampled. Cormack-Jolly-Seber models were used to estimate annual survival of giraffes at OGR. The mean percentage of newborn calves: adult female at OGR (~18%) was significantly higher than at OC (3.3%) and MTC (0%). The mean juvenile: adult female percentage at the Siria Plateau sites was 62 ± 12.8% versus 12% in MTC. Total juvenile calves averaged 22% on the plateau, four times higher than MTC (5.3%). At OGR, giraffe survival for all ages and sexes was 0.86, higher than protected areas with lions. Only one female giraffe in 229 used both plateau sites, suggesting independent matrilines. Human-populated savannah next to reserves contributes to giraffe recovery, but nursery areas like OGR need robust protection.