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Venter, J.

Publications and source records attributed to Venter, J..

4 recordsLinked to original sources
bioRxiv2026

Effect of the environment, predation and life history on reproductive synchrony in Perissodactyla

Synchronising birth timing with the adequate environmental conditions as well as with congeners can affect juvenile survival and at a later stage, recruitment. In the case of endangered species, understanding the factors driving birth phenology is therefore critical to implement effective conservation and reintroduction policies. Currently, 75% of the Perissodactyla species (odd-toed ungulates) are threatened and some even already had to be reintroduced in their natural habitat. Using a comparative analysis framework, we investigated the effect of nine environmental, life history and predation factors on the synchrony of births in 27 populations of wild Perissodactyla across Africa and Asia. We confirmed the positive effect of environmental seasonality and latitude, as well as the negative effect of environmental productivity on birth synchrony, but we found no significant effect of environmental unpredictability. Life history traits had limited effects on birth synchrony in this order: the intensity of daily reproductive effort and pace of life were non-significant, and migratory behaviour had an unexpected positive association with birth synchrony, suggesting that the link between migration and reproduction might be more complex than the relief of environmental constraints initially expected. We found a positive effect of group size on birth synchrony, in line with the swamping hypothesis to reduce predation risk on neonates, but we found no strong support for a positive effect of predation exposure, measured as a qualitative index combining species-specific sensitivity to predation and site-specific predator abundance. Overall, our findings suggest that individuals adjust reproductive cycles in response to local ecological and social conditions, suggesting that conservation efforts such as reintroductions could benefit from taking into account the extent of the differences between the site of origin and the reintroduction site.

ecology↗
bioRxiv2025

Absence of reactive temporal response of baboons to the occurrence of predators

Predators exert strong selective pressure on prey species, shaping their behavioral adaptations. Prey species use proactive responses, such as site selection and the adjustment of daily activity patterns to anticipate and avoid predation exposure. In contrast, reactive responses, including fleeing, referential signaling and retaliation, occur after encountering a predator to mitigate the immediate predation risk. The presence of a predator in an area can also generate longer-term responses, such as reactive avoidance, defined here as the temporary avoidance of the area following the passage of a predator. Such a long-term reactive response remains understudied in primates. To investigate reactive avoidance, we analyzed an extensive camera trap data set of 3,042 detections (defined here as a motion-triggered event of three pictures per trigger during the day and one picture at night) of both chacma (Papio ursinus) and olive (Papio anubis) baboons, including 6,958 detections of their main predators, lions (Panthera leo), leopards (Panthera pardus) and spotted hyenas (Crocuta crocuta), in four savanna sites (Madikwe Game Reserve, Tswalu Kalahari Private Wildlife Reserve and the Associated Private Nature Reserves, South Africa; Serengeti National Park, Tanzania). We examined whether baboons display species-specific reactive avoidance towards predators up to 72 hours after the detection of a predator using randomization tests. We found no significant decrease in baboon presence (defined as the number of baboon detections) 0 to 24 hours, 24 to 48 hours and 48 to 72 hours after the detection of any predator species. These results suggest that baboons may not display reactive avoidance and rely on alternative predator-avoidance strategies, such as proactive avoidance or aggressive retaliation, to mitigate predation risk.

animal behavior and cognition↗
bioRxiv2024

Climate and predation drive variation of diel activity patterns in chacma baboons (Papio ursinus) across southern Africa

Understanding how animals adjust daily activity to environmental gradients reveals key drivers of behavioral plasticity. While diel activity is theorized to reflect trade-offs among thermoregulation, energy balance, and predation risk, few studies test these interactions at broad spatial scales within species. We investigated this in chacma baboons (Papio ursinus) using over a million camera-trap detections across 29 sites in six biomes (2016-2022) in South Africa and Zimbabwe. Activity declined by about 3% with latitude, consistent with lower resource predictability and increased with thermal stress, while sleep and wake times were similar across sites. Baboons avoided midday heat but increased dawn and night activity under predator pressure. These findings show how abiotic and biotic pressures shape diel schedules and highlight temporal flexibility as an adaptive strategy for generalist mammals in a changing world.

animal behavior and cognition↗