No abstract

Large carnivores are frequently released for conservation purposes, but early efforts struggled with inadequate monitoring and reporting, resulting in poor understanding of success. Although managers have improved release practice and monitoring, the use of orphaned, captive-raised large carnivores for release remains controversial because of the potential influence of captivity and the possible lack of natural behaviours in such individuals. Yet, rehabilitating orphaned individuals for release could help mitigate pressures on vulnerable wild populations. We present a case study on the rearing, rehabilitation and release of wild-born cheetahs Acinonyx jubatus that were rescued as orphans in Namibia. Our aim was to develop a methodological framework for cheetah release planning and post-release management based on the outcome of release trials conducted during 2004–2018. Between 2001 and 2012, we rescued 86 orphaned cheetahs from the wild. Of these, 36 (42%) were selected as release candidates. We found high success rates (75–96%) of selected individuals in achieving independence post-release. Additionally, annual survival estimates for rehabilitated individuals that reached independence were comparable to those of wild counterparts described by other studies, and some rehabilitated individuals reproduced with wild conspecifics. Our findings demonstrate the ability of wild-born, captive-raised cheetahs to transition back into the wild with strategic pre- and post-release management directed towards optimizing survival. This includes selecting appropriate release candidates, forming artificial coalitions, balancing habituation levels during captivity, choosing appropriate release sites, and providing strategic support during post-release monitoring. We encourage scientists and managers to implement and refine our protocol for rehabilitation throughout the cheetah's current and historic range.

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Vertebrate communities in headwater streams are assumed to be regulated through competitive and predatory interactions. Although documented predation is rare, studies regularly report competitive dominance by fish that, as larger competitors reliant on aquatic habitat, exclude semi‐aquatic salamanders to marginal stream habitat. However, it is unclear whether fish interact with stream‐breeding salamanders through indirect effects such as competition for resources (e.g. food or cover) or fear (i.e. threat of predation) nor is it known whether these interactions are consistent through time. This study used a novel caging approach to determine if competitive outcomes between a headwater fish and salamanders were regulated primarily through resource depletion (exploitative competition) or behavioural avoidance (interference competition). We paired banded sculpin (Cottus carolinae) and larval red salamanders (Pseudotriton ruber) of similar body size in independent flow through mesocosms with intra‐ and inter‐specific pairs allowed to interact physically or non‐physically. The experiment was repeated in the autumn and in the spring when stream salamander larvae begin to transform into terrestrial juveniles. Banded sculpin negatively influenced growth of red salamanders regardless of whether they were allowed to physically interact, suggesting interference competition and behavioural avoidance. This asymmetrical effect was strongest in the spring when salamanders underwent metamorphosis at higher rates in the presence of fish. However, in the autumn, the effects were more balanced between the two species with salamanders impacting fish through exploitative competition. By studying the temporal relationships between two competitors and using a caging method novel to competition studies, we established that the outcomes of competition are dependent on season and may vary in type relative to the timing of life‐history events. For this community, these results suggest that outcomes of competition are highly dependent on season and could indicate a biotic mechanism maintaining headwater salamander distributions through source–sink dynamics. Our results also suggest that, in this species interaction, it may be unwarranted to assume that the outcomes of competition at one time represent the complex relationships regulating community interactions.

Scent‐marking sites may facilitate interspecific information gathering and could help to minimise the risk of encounter with interspecific competitors. Recent evidence from South Africa shows that cheetahs avoid dominant predators at scent‐marking sites, which may delay or inhibit intraspecific communication in cheetahs. However, little is known on whether this pattern of avoidance occurs elsewhere in the cheetah's range. We analysed a 9‐year camera trap data set from north‐central Namibia to explore interspecific use of marking sites by cheetahs and leopards. We documented frequent sharing of marking sites, which was likely facilitated through temporal segregation and by availability of alternative sites that were species‐specific. We did not identify a stronger avoidance response of cheetahs to leopards than to conspecifics, suggesting that delayed communication by cheetahs resulting from predator avoidance may be limited in our study area. Seasonality affected patterns of marking site visitation, which may be attributed to behavioural changes in relation to reproduction or resource availability, or to differential detectability of olfactory cues among seasons. We recommend further research to better understand carnivore scent‐marking, including behavioural responses to olfactory cues and environmental conditions, as well as intra‐ and interpopulation differences.