Temporal activity patterns suggesting niche partitioning of sympatric carnivores in Borneo, Malaysia

To propose proper conservation measures and to elucidate coexistence mechanisms of sympatric carnivore species, we assessed temporal activity patterns of the sympatric carnivore species using 37,379 photos collected for more than 3 years at three study sites in Borneo. We categorized activity patterns of nine carnivore species (one bear, three civets, two felids, one skunk, one mustelid, one linsang) by calculating the photo-capturing proportions at each time period (day, night, twilight). We then evaluated temporal activity overlaps by calculating the overlap coefficients. We identified six nocturnal (three civets, one felid, one skunk, one linsang), two diurnal (one felid, one mustelid), and one cathemeral (bear) species. Temporal activity overlaps were high among the nocturnal species. The two felid species possessing morphological and ecological similarities exhibited clear temporal niche segregation, but the three civet species with similar morphology and ecology did not. Broad dietary breadth may compensate for the high temporal niche overlaps among the nocturnal species. Despite the high species richness of Bornean carnivores, almost half are threatened with extinction. By comparing individual radio-tracking and our data, we propose that a long-term study of at least 2 or 3 years is necessary to understand animals’ temporal activity patterns, especially for sun bears and civets, by camera-trapping and to establish effective protection measures.

Temporal partitioning and spatiotemporal avoidance among large carnivores in a human-impacted African landscape

Africa is home to some of the world’s most functionally diverse guilds of large carnivores. However, they are increasingly under threat from anthropogenic pressures that may exacerbate already intense intra-guild competition. Understanding the coexistence mechanisms employed by these species in human-impacted landscapes could help shed light on some of the more subtle ways in which humans may impact wildlife populations, and inform multi-species conservation planning. We used camera trap data from Tanzania’s Ruaha-Rungwa landscape to explore temporal and spatiotemporal associations between members of an intact East African large carnivore guild, and determine how these varied across gradients of anthropogenic impact and protection. All large carnivores except African wild dog (Lycaon pictus) exhibited predominantly nocturnal road-travel behaviour. Leopard (Panthera pardus) appeared to employ minor temporal avoidance of lion (Panthera leo) in all sites except those where human impacts were highest, suggesting that leopard may have been freed up from avoidance of lion in areas where the dominant competitor was less abundant, or that the need for leopard to avoid humans outweighed the need to avoid sympatric competitors. Lion appeared to modify their activity patterns to avoid humans in the most impacted areas. We also found evidence of avoidance and attraction among large carnivores: lion and spotted hyaena (Crocuta crocuta) followed leopard; leopard avoided lion; spotted hyaena followed lion; and lion avoided spotted hyaena. Our findings suggest that large carnivores in Ruaha-Rungwa employ fine-scale partitioning mechanisms to facilitate coexistence with both sympatric species and humans, and that growing human pressures may interfere with these behaviours.

Temporal Activity Patterns of Sympatric Bornean Carnivore Species: Implications for Niche Partitioning and Conservation

To propose proper conservation measures and to elucidate coexistence mechanisms of sympatric carnivore species, we assessed their temporal activity patterns using 37,379 photos collected for more than three years at three study sites in Borneo. We categorized activity patterns of nine carnivore species (one bear, three civets, two felids, one skunk, one mustelid, one linsang) by calculating the photo-capturing proportions at each period (day, night, twilight). We then evaluated temporal activity overlaps by calculating the overlap coefficients. We identified six nocturnal (three civets, one felid, one skunk, one linsang), two diurnal (one felids, one mustelid), and one cathemeral (bear) species. Temporal activity overlaps were high among the nocturnal species. The two felid species possessing morphological and ecological similarities exhibited clear temporal niche segregation, but the three civet species did not. Broad dietary breadth may compensate for the high temporal niche overlaps among the nocturnal species. Despite the high species richness of Bornean carnivores, almost half are threatened with extinction. By comparing individual radio-tracking and our data, we propose that a long-term study of at least three years is necessary to understand animals’ temporal activity patterns by camera-trapping and to avoid diverting conservationists away from effective protection measures.

Assessing the Impacts of Competition and Dispersal on a Multiple Interactions Type Model

Multiple interactions (e.g., mutualist-resource-competitor-exploiter interactions) type models are known to exhibit oscillatory behaviour as a result of their complexity. This large-amplitude oscillation often de-stabilises multispecies communities and increases the chances of species extinction. What mechanisms help species in a complex ecological system to persist? Some studies show that dispersal can stabilise an ecological community and permit multi-species coexistence. However, previous empirical and theoretical studies often focused on one- or two-species systems, and in real life, we have more than two-species coexisting together in nature. Here, we employ a (four-species) multiple interactions type model to investigate how competition interacts with other biotic factors and dispersal to shape multi-species communities. Our results reveal that dispersal has (de-)stabilising effects on the formation of multi-species communities, and this phenomenon shapes coexistence mechanisms of interacting species. These contrasting effects of dispersal can best be illustrated through its combined influences with the competition. To do this, we employ numerical simulation and bifurcation analysis techniques to track the stable and unstable attractors of the system. Results show the presence of Hopf bifurcations, transcritical bifurcations, period-doubling bifurcations and limit point bifurcations of cycles as we vary the competitive strength in the system. Furthermore, our bifurcation analysis findings show that stable coexistence of multiple species is possible for some threshold values of ecologically-relevant parameters in this complex system. Overall, we discover that the stability and coexistence mechanisms of multiple species depend greatly on the interplay between competition, other biotic components and dispersal in multi-species ecological systems.

Coexistence patterns and diversity in a trait-based metacommunity on an environmental gradient

The dynamics of trait-based metacommunities have attracted much attention, but not much is known about how dispersal and environmental variability mutually interact with each other to drive coexistence mechanisms and diversity patterns. Here, we present a spatially-explicit model of resource competition in a metacommunity on a one-dimensional environmental gradient and analyse the joint influence of dispersal and environmental variability on coexistence mechanisms, spatial structure, trait distribution and local and regional diversity. We find that without dispersal, species are sorted according to their optimal position on the gradient, but with the onset of dispersal source-sink effects are initiated. Thereby, the dispersal rate and the range of spatial environmental variability strongly affect the competition outcomes, composition, and diversity. That is, at low dispersal rates the number of surviving species increases with the spatial environmental variability. Increasing dispersal rates generates trait lumping and strengthens environmental filtering so that only a few dominant species can survive. Interestingly, for very large dispersal rates the system becomes spatially homogeneous, but nevertheless two specialists at the extreme ends of the trait-off curve can coexist. Global species richness depends in an intricate manner on dispersal strength and resource variability, with a classic hump-shaped dependence of diversity on dispersal rate, but also a pronounced peak of global diversity for intermediate values of resource variability. Our findings thus provide important insights into the factors that shape metacommunity structure and promote coexistence and about how spatial environmental variability can lead to different competition outcomes in metacommunities.

A new framework to understand context dependence of two-species population dynamics: A case study of rocky intertidal sessile assembly

How population dynamics depend on changes in the environment is a classic but important question in ecology. We propose a new framework to understand the context dependence of the mechanism driving two-species population dynamics, in which we use intrinsic growth rates as a proxy for environmental suitability, then assess how the strengths of intra- and interspecific density dependence in a two-species system change depending on environmental suitability. By using census data for pairwise sessile species on a rocky intertidal shore, collected over 18 years, we showed that the strength of both intra- and interspecific density dependence decreased as the environmental suitability of the focal species increased, but was scarcely affected by the environmental suitability of the other species. Combining this framework with modern coexistence theory could provide a deeper understanding of coexistence mechanisms and context-dependence in two-species systems.

Combined Impacts of Predation, Mutualism and Dispersal on the Dynamics of a Four-Species Ecological System

Multi-species and ecosystem models have provided ecologist with an excellent opportunity to study the effects of multiple biotic interactions in an ecological system. Predation and mutualism are among the most prevalent biotic interactions in the multi-species system. Several ecological studies exist, but they are based on one-or two-species interactions, and in real life, multiple interactions are natural characteristics of a multi-species community. Here, we use a system of partial differential equations to study the combined effects of predation, mutualism and dispersal on the multi-species coexistence and community stability in the ecological system. Our results show that predation provided a defensive mechanism against the negative consequences of the multiple species interactions by reducing the net effect of competition. Predation is critical in the stability and coexistence of the multi-species community. The combined effects of predation and dispersal enhance the multiple species coexistence and persistence. Dispersal exerts a positive effect on the system by supporting multiple species coexistence and stability of community structures. Dispersal process also reduces the adverse effects associated with multiple species interactions. Additionally, mutualism induces oscillatory behaviour on the system through Hopf bifurcation. The roles of mutualism also support multiple species coexistence mechanisms (for some threshold values) by increasing the stable coexistence and the stable limit cycle regions. We discover that the stability and coexistence mechanisms are controlled by the transcritical and Hopf bifurcation that occurs in this system. Most importantly, our results show the important influences of predation, mutualism and dispersal in the stability and coexistence of the multi-species communities

Spatial distribution of four sympatric owl species in Carpathian montane forests

Knowledge about spatial distribution of owl species is important for inferring species coexistence mechanisms. In the present study, we explore spatial patterns of distribution and habitat selection of four owl species – Eurasian pygmy owl (Glaucidium passerinum), boreal owl (Aegolius funereus), tawny owl (Strix aluco) and Ural owl (Strix uralensis) – ranging in body mass from 50 g to 1300 g, with sympatric occurrence in temperate continuous montane forests in the Veľká Fatra Mts., Western Carpathians, central Slovakia. Locations of hooting owl males were surveyed between 2009–2015 in an area of 317 km2. Spatial point pattern analysis was used for analysis of owl distribution. Random patterns of owls’ spatial arrangement dominate at both intra‐ and interspecific levels within the studied area. Only intraspecific distribution of pygmy owls and interspecific distribution of Ural owls toward tawny owls exhibited positive associations. This discrepancy with other studies can be explained in terms of pygmy owls’ preference for high‐quality nest sites and/or spatial clustering in their prey distribution, and due to aggressive behaviour of dominant Ural owls toward subdominant tawny owls, respectively. Moreover, we found considerable overlap in habitat preferences between owl species, considering stand age, stand height, tree species richness, distance to open area, elevation, slope, percentage of coniferous tree species and position on hillslope, although pygmy owls were not registered in pure broadleaved stands, Ural owls were not registered in pure coniferous stands, and boreal and Ural owls were more common on slope summits and shoulders than tawny and pygmy owls. The observed patterns of spatial arrangement might suggest developed coexistence mechanisms in these owl species; differences between studies may indicate complex interactions between intra‐ and interspecific associations and habitat quality and quantity, food availability and owl species involved in those interactions on a landscape scale.