Abstract Land tenure is a fundamental ecological process in territorial animals; it reflects how individuals establish and maintain access to space and resources. First conceptualised by Hornocker in 1969, it provides an early understanding of population dynamics. However, this critical aspect for interpreting the stability, predictability and exclusivity of a population is rarely evaluated. To date, there has been no clear ecological definition of the land tenure system. To understand this concept, we review more than 50 years of research on territorial carnivores and synthesise how land tenure has been quantified across taxa. We examine how this aspect links population and demographic processes that lead to species conservation in various landscape scenarios. The goal is to develop a standardised approach across species and landscapes to evaluate land tenure by providing a framework and testable hypotheses. As land tenure provides critical insights into the spatial stability of populations and informs conservation planning, its limited integration into ecological studies remains concerning despite advances in population ecology and monitoring technologies. We attempted to build a foundation for future research that aims to measure population stability and species persistence.
Abstract Medium‐ and large‐sized terrestrial mammals play key ecological roles in tropical forests; however, the relative importance of environmental filters and anthropogenic disturbances in structuring their assemblages in Amazonian campinarana (white‐sand) ecosystems remains poorly understood. In this study, we evaluated the influence of these factors on species composition and habitat use by medium‐ and large‐sized terrestrial mammals, as well as by the frugivore–herbivore guild in Amazonian campinarana ecosystems. We used camera traps and structural equation modelling. We recorded 22 species over 4721 camera‐trap days, with assemblages dominated by frugivore–herbivores and by dietary and habitat generalists, such as the common opossum ( Didelphis marsupialis ). Habitat use by the overall mammal assemblage was higher in areas with lower vegetation height, whereas terrain elevation relative to the nearest drainage (HAND index) had an indirect effect mediated by vegetation structure. In contrast, frugivore–herbivore species showed more selective responses, with higher habitat‐use intensity in areas farther from human influence. Mammal assemblages were predominantly influenced by distance to houses, whereas the composition of the frugivore–herbivore guild was associated with distance to houses and tree height. Our results demonstrate that even low levels of human presence are sufficient to structure mammal assemblages, reinforcing the need for spatially explicit management strategies aimed at conserving the functional integrity of these unique and highly sensitive ecosystems.
Abstract African forest elephants ( Loxodonta cyclotis ) are critically endangered ecosystem engineers of African tropical forests. Despite their rapidly declining population trend, little is known of how forest elephants interact with other vertebrate assemblages. To explore this, we studied avian communities within a continuous tropical rainforest on the slopes of Mt. Cameroon. The area's topography allowed us to survey birds in elephant‐grazed primary forest and in adjacent portions that elephants avoid, isolating the effect of megafaunal grazing within an otherwise intact system. We additionally surveyed nearby secondary forests fragmented by human activity, contrasting the disappearance of a single ecosystem engineer against the reshaping of forest by anthropogenic disturbance. We assessed the taxonomic diversity (species richness, Shannon index), functional diversity (Rao's quadratic entropy), functional redundancy (species overlap in functional space), and composition of functional traits (abundance‐weighted trait averages). Previous research suggested that loss of forest elephants would negatively impact avian assemblages through reduced habitat heterogeneity. In contrast, we show that elephant grazing itself significantly reduced species richness, to levels comparable with heavily disturbed secondary forests. Functional diversity nevertheless increased in both the grazed and secondary forest, but at the cost of functional redundancy: in both of these habitats, the avian assemblages were taxonomically impoverished, yet functionally more dispersed, with some foraging niches negatively affected. The elephant‐grazed forest was dominated by understory and terrestrial invertivores, whereas the ungrazed forest supported frugivores and larger birds. The secondary forest, in turn, harboured a functionally distinct assemblage of open‐habitat species with high dispersal ability and divergent foraging strategies. Together these patterns show that although elephant grazing reduces taxonomic diversity to a degree comparable with anthropogenic disturbance, it reshapes functional composition in fundamentally different ways. The presence of forest elephants facilitates stable populations of forest specialist birds, such as terrestrial invertivores. Conversely, the adverse effects of elephant grazing on frugivores and large birds could be minimized by establishing larger reserves of lightly grazed forest, possibly alongside ungrazed refuges. Overall, our results show that loss of keystone megaherbivores has widespread consequences for other rainforest vertebrates, potentially resulting in a cascading restructuring of key ecosystem functions.
Abstract Research Highlight: Geng, Y., Mammides, C., He, R.‐C., Wang, L., Luo, K., Zhang, Z.‐Y., Wang, B., & Quan, R.‐C. (2026). Human hunters are no substitute for vanishing apex predators. Journal of Animal Ecology , 1–13. https://doi.org/10.1111/1365‐2656.70306 . As large carnivores decline and humans rise to become the planet's most influential predator, scant consideration has been given to the functional roles of hunters (and fishers) in ecological communities. In novel, landscape‐scale work, Geng et al. (2026) ask whether hunters can serve similar roles as the predators they are replacing. Camera‐trap records from 400 sites characterized as apex predator‐dominated, hunter‐dominated and predator‐absent were analysed across multiple ecological measures. Apex predator‐dominated sites hosted ~30% more species and nearly 50% greater abundances of mammals. Network measures of prey populations were most robust at apex predator sites and weakest at hunter‐dominated sites. Finally, prey showed up to 2.6 times longer avoidance times following hunter presence. These striking patterns suggest that hunters do not replicate the ecological influence of the area's vanishing predators. Work like this can benefit from much more data about human predators. Specifically, ecologists can confront in careful ways the conceptual, methodological and ethical constraints of studying our own species as predators. Outcomes could include greater knowledge about the ecological influence of the planet's ‘super predator’, the underlying mechanisms, and related insight to apply to mitigation.
Abstract Long‐term ecological studies testing global change impacts are rare yet essential in the Arctic, a region warming nearly four times faster than the global average. These rapid environmental changes reshape ecosystem functioning across the pan‐Arctic and affect the livelihoods of local communities. Seabirds are widely recognised indicators of environmental change. Identifying species‐specific critical constraints is therefore essential for detecting early warning signals of population decline and ecosystem reorganisation. Little auks ( Alle alle ), the most abundant Arctic seabirds, are key ecosystem engineers shaping coastal environments through for example food‐web interactions and guano deposition. We present a 20‐year study (2005–2024) of an East Greenland little auk population, combining long‐term demographic monitoring with behavioural, physiological and ecotoxicological data. We quantified fitness‐related traits (adult body condition, overwinter survival and chick growth) alongside potential constraints, including parental foraging effort, trophic ecology, winter distribution, and mercury contamination in adults, eggs and chicks. Over the study period, climate‐driven ocean warming, sea‐ice decline, altered zooplankton communities, and increasing mercury exposure reshaped environmental conditions. Faced with these changes, little auks exhibited marked behavioural and dietary plasticity, allowing them to maintain relatively stable fitness metrics in most years. However, sustained monitoring revealed key constraints that undermine this apparent resilience: (a) Elevated mercury burdens may reduce aerobic diving capacity and thermal tolerance in adults and were associated with reduced reproductive performance. (b) Chick growth was strongly impaired during years with increased summer storm activity, which disrupted adult foraging trips and provisioning rates. Winter storms are also likely to negatively affect adult overwinter survival. Together, these findings show that little auks can partially buffer rapid Arctic change through behavioural flexibility, but multiple interacting climatic and contaminant stressors impose increasing, possibly cumulative constraints on performance. Identifying such critical constraints is crucial for understanding the limits of resilience in wild populations and for improving predictions of ecosystem responses to ongoing climate change.
