Rehabilitating and releasing cheetahs 499
stopped as soon as cheetahs began making successful kills at regular intervals (Supplementary Material 3). A registered veterinarian was on standby for any emergency situation.
End of intensive post-release monitoring period Once a cheetah settled into a behavioural routine expected of a wild cheetah (i.e. no longer requiring regular supplemental feeding, visiting water points, and stabilization of initial exploratory behaviour; Marker et al., 2018a,b; Wachter et al., 2018), the monitoring team would end the intensive post-release monitoring period. From then on, cheetahs were onlymonitored via theirGPS/VHF collars and observed when they were easy to find or when they were seen opportunistically.
Assessment of release success
We evaluated the success of released cheetahs based on achieved independence and survival.
Independence achieved We considered a released cheetah to have achieved independence once they began making kills at regular intervals and no longer required supplemental feeding for survival. If an individual or group failed to reach independence or displayed behaviour suggesting they would fail to achieve independence, we considered their release a failure and returned them to permanent captivity.
Survival To assess cheetah survival, we calculated Kaplan– Meier survival estimates with the product limit estimator using a staggered entry design (Kaplan & Meier, 1958; Pollock et al., 1989). This method allowed the inclusion of animals entering the study at irregular intervals and accom- modates data from censored individuals (individuals with unknown fates when collars fail or deplete). Survival esti- mates were based on the time individuals survived during both the training–release (if applicable) and the post-release monitoring period. We did not include released individuals that returned to captivity after a failed training–release or release in our survival analyses. We used log rank tests to compare survival curves between social grouping (male coalition, reserve; female coalition, reserve; single females, reserve; single females, farmland), and trained/non-trained individuals (Pollock et al., 1989). Two continuous variables were also investigated, after being transformed into catego- rical factors. Age when orphaned was split into individuals orphaned at ,6 months of age and individuals orphaned at $6 months of age, to assess whether individuals ,6 months old could be considered for release when bonded to older individuals. Captivity timewas divided into individ- uals in captivity,1,500 days and$1,500 days. Survival was estimated for consecutive 3-month periods to investigate differences throughout the post-release period, as Weise et al. (2015) detected increased mortality in the first 3
months after the release of translocated cheetahs. Analysis was done in R 4.0.4 (R Core Team, 2021).
Results
Selected release candidates Of 86 wild-born, captive-raised orphaned cheetahs rescued during 2001–2012, 42% were selected for rehabilitation based on age on arrival and health status. The 36 individuals (15 males, 21 females) were divided into 20 release groups (Table 3); four male coalitions (CM1 to CM4), three female coalitions (CF1 to CF3), 12 single females (SF1 to SF12), and one female with cubs (FC1). Candidates selected for release were orphaned at 3–13 months of age (mean 7.28 ± 2.61 SD months), spent 1.5–9 years in captivity (mean 4.76 ± SD 1.87 years) before release, and were released at 2.5–10 years of age (mean 5.56 ± 1.81 years).
Releases
Releases took place during 2004–2018. Eight training–releases involving 17 individuals were attempted. Three (CF2,FC1, CM2) of the eight groups were hard-released in Erindi, and a fourth (SF2) was soft-released into the Greater Waterberg Landscape prior to being hard-released into Erindi (Table 3). Of the 12 groups that did not undergo training, ninewere soft- released into theGreaterWaterberg Landscape, one (CF3)was soft-released into NamibRand, one (SF5) was soft-released twice, first into the Greater Waterberg Landscape and later into Erindi following veterinary treatment for an injury sustained in the first release, and one (CM3) was first hard- released into NamibRand, but recaptured as they began moving out of the Reserve, and then soft-released back into NamibRand (Table 3).
Evaluation of release success
Training–release outcomes Of the 17 (7 M, 10 F) cheetahs that underwent training–release, 52%(n = 9; 4 M, 5 F) suc- cessfully reached independence and were subsequently released, and 48%(n = 8; 4 M, 4 F) failed to reach indepen- dence and were returned to captivity. Of these eight, two females (CF1) escaped the training camp and killed a goat, two females (SF3,SF4) failed to make successful kills and throughout their training–release period showed abnormal- ly low interest in trying to hunt, and four males (CM1) remained at the release enclosure and did not explore the training camp or attempt to hunt.
Time to independence Of the 36 cheetahs selected for re- lease, 75%(10 M, 17 F) achieved independence. Eight individ- uals failed to achieve independence during the training–
Oryx, 2022, 56(4), 495–504 © The Author(s), 2022. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605321000235
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