Binod Borah

Foraging decisions are a central driver of animal movement, shaping how individuals navigate heterogeneous landscapes to meet energetic demands. Movement emerges from the interaction between the external resource environment and an animal's capacity to perceive, evaluate, and track resources across space and time. These multi‐scaled foraging and movement decisions can reduce frugivore travel costs or increase resource profitability, while also having consequences for seed dispersal patterns. Here, we studied the foraging and movement decisions of a tropical frugivore, white‐handed gibbon Hylobates lar , tested how these decisions affected simulated seed dispersal distances, and compared dispersal distances to those generated by foragers making random decisions. We used patch‐to‐patch and patch‐to‐sleep site models to test if gibbons accounted for distance and productivity while selecting resources or sleep sites. We then simulated gibbon movement between resource patches or sleep sites, and modeled seed dispersal along their movement tracks. Gibbons discounted distant and previously exploited resources and generated longer seed dispersal distances than random foragers. By explicitly estimating the strength and direction of these foraging decisions, our study demonstrates that the foraging decisions, movement, and dispersal services of seed dispersers are interlinked, highlighting the functional importance of animal movement for both animal and plant fitness and ecosystem processes.

The loss of large frugivorous birds can impact their plant partners through loss of ecological services, like long‐distance dispersal of seeds. Yet, interaction rewiring, or the redistribution of interactions among remaining bird species, might help counteract the loss of long‐distance dispersal from large bird extinctions. Here, we tested if rewiring could mitigate loss of long‐distance dispersal and whether its effectiveness differed among plants with small and large fruits at different scales. We analyzed interaction data from eight Andean bird–plant seed dispersal networks, simulated extinction of large birds, allowed for lost interactions to rewire based on previous observed interactions, trait‐matching between birds and plants, and similarity in body sizes among birds (trait‐resemblance), and related changes in long‐distance dispersal to fruit‐size ratios. At the local scale, reduction in long‐distance dispersal varied among individual networks depending on whether rewiring occurred or not and the type of rewiring. At the regional scale, after aggregating results across local networks, reduction in long‐distance dispersal was between 20 and 40% for relatively small‐fruited plants (size ratio ≤ 0.25) and between 40 and 80% for relatively large‐fruited plants (size ratio ≥ 0.75) without interaction rewiring. However, with rewiring, reduction in long‐distance dispersal of smaller‐fruited plants was limited to 4% and between 4 and 10% for larger‐fruited plants. Thus, interaction rewiring can buffer losses in ecological functions, such as long‐distance dispersal, in response to large bird extinction, although relatively large‐fruited plants remain more vulnerable than smaller‐fruited plants.

The majority of woody plant species on Barro Colorado Island (BCI) are dispersed by animals. We review research relevant to understanding the processes and consequences of seed dispersal on BCI, focusing on primary seed dispersal by animals. We first review patterns of primary seed dispersal and then discuss studies that quantify the effectiveness of dispersal by primates, bats, and ants. The wealth of information from research conducted on BCI has provided insights into the patterns, mechanisms, and consequences of seed dispersal. Future research integrating movement ecology, chemical ecology, seed dispersal effectiveness, and mechanistic models can help advance our understanding of the role of seed dispersal for plant population dynamics and biodiversity.

Frugivore movement plays a critical role in animal‐mediated seed dispersal. Frugivores utilize resources that are heterogeneously distributed in the landscape and execute complex movement to exploit these resources. Employing the ‘movement ecology paradigm', we discuss the drivers behind frugivore movement, categorize movement into canonical activity modes and explore the potential impacts on seed dispersal effectiveness via removal and deposition of seeds. Among the movement drivers, frugivore physiology determines the goals, motion capacities determine how frugivores move across their heterogenous landscape, navigation capabilities determine how frugivores acquire and process both internal and external information that set them in motion, and biotic interactions further modulate frugivore movement. The movement process that emerges from the interactions of these drivers can be classified into different canonical activity modes that determine levels of seed removal and generate clumped, even or other spatial distributions of seed deposition. We provide a novel framework to integrate movement drivers, frugivore activities and seed dispersal services. We provide future directions utilizing advances in animal movement research to better understand the role of animal movement in the effectiveness of seed dispersal, highlighting potential impacts of increased anthropogenic activities. To advance a mechanistic understanding of animal‐mediated seed dispersal, we encourage increased collaboration between animal movement and plant ecologists.

Fifteen extant species of cats inhabit India, and the northeastern region of the country is among the richest with nine species. Among these are the “standard four”, an assemblage of Clouded Leopard Neofelis nebulosa, Asiatic Golden Cat Catopuma temminckii, Marbled Cat Pardofelis marmorata, and Leopard Cat Prionailurus bengalensis, which also occur across southeastern Asia. Within India, despite several surveys in this region, very little information exists on the ecology of this assemblage to explain their co-occurrence. In this paper, we put together data from several independent camera trapping studies over 10 sites across northeastern India to examine and interpret diel activity patterns of this group. While we present results for all the four species, we focus on two species, the Marbled Cat and Leopard Cat, which are of very similar body size and are potential competitors. We used kernel density estimates to measure diel activity patterns of all four species and overlap in activity between Marbled Cat and Leopard Cat at the regional scale as well as the point scale. We obtained 783 captures of the standard four from >27,500 trap nights. The Asiatic Golden Cat and Marbled Cat were strongly diurnal, Clouded Leopard largely crepuscular and nocturnal, and Leopard Cat largely nocturnal. The degree of overlap between Marbled Cat and Leopard Cat activity was low and in consensus with other studies across southeastern Asia. We interpret this as the differing niche spaces of the two cats due to their specific pre-existing adaptations, not restricted to the effects of competition. The point scale analysis when both cats are captured at the same location and separately show no shift in activity pattern, supporting our hypothesis of pre-existing differences in resources, such as food, playing a major role in facilitating co-existence. Our study, however, is preliminary and additional information with robust analysis is required to test this finding.

Non‐trophic interactions (or, inter‐species associations) play a prominent role in determining community structure and function. Mixed‐species bird flocks are networks of non‐trophic associations that confer foraging and anti‐predator benefits to participant species. Yet, the responses of these interspecific associations to anthropogenic environmental changes are poorly understood. Selective logging is pervasive in the tropics, and can affect associations in mixed‐species bird flocks by altering resource availability and/or predation risk, or through the altered abundances of species participating in mixed flocks. Across a gradient of logging intensity, we examined how the number and strength of associations in two different mixed‐species flock types responded to logging intensity, while simultaneously controlling statistically for changes in the abundances of species in response to logging. Across the logging gradient, we used network analyses to: (1) quantify the proportion of potentially realizable associations, and (2) measure the strengths of these realized associations. For both these analyses, we used null models to investigate whether changes in the network properties of mixed flocks were simply abundance‐driven, or congruent with expectations of how flock properties might be modified by selective logging. In understorey flocks, after controlling statistically for changing abundances of participant species, the proportion of realized associations decreased with increasing logging intensity, whereas mean association strength did not show any relation with logging intensity. In midstorey flocks, both the proportion and mean strength of realized associations increased with increasing logging intensity. Synthesis and applications. By statistically separating abundance and behaviour‐mediated effects, we show that interspecific associations in mixed‐species bird flocks respond to potential resource and/or predation changes from logging, but that their functional roles persist in logged forest. We show that logged forests can conserve not only community richness, but also function. Thus, these logged forests must be prevented from ongoing conversion into non‐forest habitats such as agriculture and plantation.