African snakes display a range of defensive behaviours. However, there are limited quantifiable data on specific retaliatory behaviours for most species in response to threat-eliciting stimuli and the factors that might influence defensive behaviours, particularly in instances of human-snake conflict. We investigated defensive striking behaviour of four African snake species: puff adder (Bitis arietans), black mamba (Dendroaspis polylepis), snouted cobra (Naja annulifera) and Mozambique spitting cobra (Naja mossambica), including the impact of snake body size and sex on striking behaviours and strike performance. Individuals were presented with a fake arm model to simulate a human arm, and behaviours were recorded in two sequential trials. Of the 14 D. polylepis individuals tested, ten defensively struck at the hand and eight of these individuals bit the hand. Three of the seven N. annulifera struck with only two resulting in bites and of the six B. arietans individuals, four struck the hand and three bit the hand. None of the 21 N. mossambica individuals struck or bit the hand. Body size and sex were not significant predictors of striking behaviour. Defensive behaviours were generally higher for individuals undergoing a second trial. Strike performance results showed that B. arietans displayed the highest strike accelerations over short distances, indicating high strike effectiveness at close range. This likely contributes to its status as the species responsible for most snakebite incidences in South Africa. The results revealed that snakes exhibit a flight response when provided the opportunity to escape, but if persistently harassed, they will strike and bite in defence. Quantifying defensive behaviours of medically important venomous snakes is crucial for addressing human-snake conflict and creating effective prevention measures. We have provided the first empirical evidence of defensive behaviours in four African snake species when presented with a simulated threat. Defensive responses and strike performance differed among species, but overall snakes chose to flee from an impending threat and only struck when they were unable to escape. These results contribute to the growing knowledge on the behavioural ecology of African snakes and provides an opportunity to create informed education and snakebite prevention tools for human-snake coexistence.
Kin groups exhibit a continuum ranging from family living to more cooperative social systems, such as cooperative breeding and eusociality. Within this continuum, some species display intermediate characteristics between family living and cooperative breeding. In this study, we tested the previously suggested possibility that the bubble-nesting anabantoid fish Betta brownorum is a family-based cooperative breeder. In aquarium experiments, the introduction of a heterospecific territory intruder induced aggression not only by breeders but also by non-breeding subordinate natal offspring tolerated within the territory. The temporary removal of subordinates increased the frequency of aggression towards the intruder by breeders. After the subordinates were returned, breeders showed less aggression towards the intruder. This suggests that subordinates alleviate the burden of work of breeders. Immediately after their return, the subordinates were frequently attacked by breeders, particularly female breeders, but such aggression regressed to the pre-removal level. Returned subordinates still attacked the intruder, although less frequently than before removal. Based on these results, we conclude that their social system bridges group living, in which intra-group cooperation is independent of offspring care, and cooperative breeding, where helping behaviour can be clearly recognized as a form of care investment. Furthermore, this study highlights the importance of distinguishing between direct and indirect care in the study of cooperative breeding. The evolution of cooperative societies, such as cooperative breeding with helping behaviour by non-parents, has attracted much attention. This study reports that the bubble-nesting anabantoid fish Betta brownorum occupies a unique position along a continuum between family living and cooperative breeding. In this species, breeding pairs tolerated natal offspring within their territory, and these offspring defended against a heterospecific intruder. Subordinates alleviated the breeders’ workload: defence by breeders increased during the temporary absence of subordinates, but decreased after their return. These results suggest that this social system represents an incipient form of cooperative breeding in which intra-family cooperation is decoupled from offspring care. Although a similar social system was found in other family-living vertebrates such as Siberian jays and Tiliquini skinks, B. brownorum exhibits unique characteristics, including a short duration of offspring care, a fast life history, and an aquatic lifestyle. This study adds to the growing number of examples of divergent cooperative societies in group-living animals.
Animals that share landscapes with people must balance the avoidance of human disturbance against the costs of avoidance itself, and movement is the currency in which this trade-off is paid. Because the distance between an animal and a person is a joint property of two trajectories, however, a change in that distance need not reflect movement by the animal. We examined how an energy-conservative, time-minimizing primate, the mantled howler monkey (Alouatta palliata), responds spatially to a recurring and mobile human presence in an agroforestry landscape, decomposing the response according to who moves and over what timescale. Using 3,116 synchronous 15-min records of group and nearest-worker locations, worker numbers, worker activity and sound levels collected across 112 days, we analysed the probability and geometry of movement, partitioned changes in monkey–worker distance into monkey- and worker-generated components, and modelled day-scale space use against daily disturbance dose. Groups moved in only 14
Understanding the drivers of social structure in free-ranging cetaceans remains challenging, as sociality emerges from the interplay between intrinsic (e.g., age, sex) and extrinsic factors (e.g., habitat characteristics, population density). In bottlenose dolphins (Tursiops spp.), social structure varies among populations, but the relative importance of multiple drivers has been hindered by the lack of standardized, comparative analyses across contrasting ecological and geographic contexts. Addressing this gap requires coordinated datasets spanning multiple populations and spatial scales. Here, we examined location-specific variation in association patterns and social network structure of Indo-Pacific bottlenose dolphins (T. aduncus) across four sites in the southwestern Indian Ocean: two in eastern Africa (southern Kenya and Zanzibar) and two remote oceanic islands (Mayotte and Reunion). We specifically assessed the potential roles of density-dependent processes, dolphin home range size and geographic isolation in shaping social structures in these populations. Across sites, dolphins in Kenya and Zanzibar exhibited the highest social connectivity and network density, consistent with their smaller home ranges and higher local densities, while maintaining moderate levels of social differentiation. In contrast, the population off Mayotte, despite low density and large home range, showed the strongest social differentiation and the most fragmented network, characterized by highly selective associations and well-defined community structure. Dolphins off Reunion displayed high network cohesion but weak pairwise associations and moderate social differentiation, suggesting a well-mixed population. Overall, our results suggest that home range size and density-dependent effects play a stronger role in shaping social structure of bottlenose dolphins than geographic isolation. The processes shaping the structure of animal societies remain a central question in behavioral ecology. By comparing bottlenose dolphin populations across four contrasting sites, this study shows that local ecological conditions—particularly population density and home range—play a stronger role in shaping social structure than geographic isolation. These findings highlight that even within a single species, social structure can vary markedly in response to environmental context. More broadly, the results emphasize the importance of considering multiple, interacting ecological drivers when seeking general patterns of sociality. Understanding how social systems respond to changing environments is especially relevant in the face of rapid ecological change, with implications for predicting the resilience of animal societies.
Understanding how nocturnal species respond to variation in moonlight is central to chronobiology and behavioral ecology. Moonlight is the dominant light source at night in many ecosystems and can influence predator-prey interactions, navigation, and foraging behavior. However, research on its effects in free-ranging terrestrial mammals is hampered by inconsistent terminology and methodological approaches. Using GPS collar data from African lions (Panthera leo) in north-central Namibia, we examined how varying definitions and measurements of moonlight affect interpretations of nighttime activity. We reviewed six influential lion studies, extracted their moonlight-related predictors, and applied each approach to a standardized dataset to evaluate resulting variation in movement patterns (lion step length). We found that model outcomes varied substantially depending on how predictors were defined. Next, we developed and compared 15 candidate models to test how specific definitions – of night, lunar illumination, moonrise/set, and cloud cover – explain variation in lion step length across sex and seasonal strata. The best-performing models included three-way interactions between lunar illumination, moonrise/moonset, and cloud cover, but explained less than 1.2
