Biotropica最新文献

Roads strongly impact wildlife movement, spatiotemporal activity patterns, species interactions, and habitat relationships. Roads can thereby affect larger ecological processes, with long-term consequences for wildlife and ecosystems. We investigated how roads shape mammal behavior, testing two key hypotheses: (1) Mammals avoid areas close to roads due to their sensitivity to traffic, and (2) The impact of roads varies between herbivores and carnivores. We collected mammal occurrence data along a 40-km-long National Highway, NH 765, which cuts through Nagarjunasagar-Srisailam Tiger Reserve, India's largest tiger reserve, and a nearby undisturbed forest trail (Peddarutla Trail) using camera traps. We recorded 16 mammal species, including endangered tigers, leopards, and dholes, using roadside habitats. Contrary to our first hypothesis, our findings revealed that mammal density overall was higher on the NH, largely due to a higher abundance of herbivores. However, carnivore richness was significantly higher on the Peddarutla Trail than on the NH, confirming our second hypothesis that herbivores and carnivores respond differently to roads. When traffic stopped, even elusive and threatened species such as tigers, leopards, and sambar were found to frequent roadsides, clearly indicating that vehicular traffic impedes the movement of mammals. This study provides clear evidence of road avoidance by carnivores and road tolerance by herbivores, and shows how roads can potentially alter mammal behavior. Our results provide first insights into the impacts of roads on mammals within a highly protected tiger reserve in India's Eastern Ghats, and underscore the urgent need for wildlife-conscious infrastructure planning, as roads increasingly threaten forests worldwide.

Knowledge of foraging resource utilization and its links to reproductive timing is important for resource management and species conservation. In this study, we examine the foraging resource utilization of the critically endangered Christmas Island flying-fox (Pteropus natalis) in relation to the timing of the species' reproductive events. To determine the diet of the species, we identified pollen and seeds collected from 608 individuals caught over 3 years, and combined these data with foraging observations. We then compared the temporal patterns in the use of diet plants to seasonal patterns in rainfall, and to the timing of reproductive events. We found that P. natalis foraged on the flowers, fruits, leaves, and stems of 57 plant species from 34 families, including most native tree species on Christmas Island, highlighting the importance of the pollination and seed dispersal services that P. natalis provides. The temporal occurrence of fruit and pollen in the diet of P. natalis correlated with changes in mean seasonal rainfall. The greatest mean proportion of fruit in the diet of P. natalis occurred during the wet season (December–March), coinciding with parturition and lactation, whereas the greatest mean proportion of pollen in the diet of P. natalis occurred during the dry season (August–November), coinciding with volancy. This research provides links between the foraging resource requirements and the timing of reproductive events in a small-island flying-fox and suggests strategies for management of important dietary resources to aid in the conservation of this threatened but ecologically important species.

Rapid urbanization has a significant impact on wildlife behavior since it alters resource availability, predation risk, and environmental conditions. Species that thrive in human-modified habitats must adjust key life-history traits, including parental care, to navigate these challenges. The House Sparrow (Passer domesticus) is a widespread human commensal that provides an ideal system to understand the effect of urbanization on parental care strategies. We investigated the sex-based differences in parental care across rural and urban habitats and their implications for reproductive success. We found that urban females exhibited significantly higher parental investment than their rural counterparts, while male investment remained consistent across habitats. However, despite this increased effort, reproductive success, as measured by hatching and fledging success, was lower in urban populations despite comparable clutch size, suggesting that urban-specific challenges such as increased predation pressure counteract the benefits of greater parental care. In rural sparrows' path analyses, models failed to detect any significant direct or cascading effects of behavior on reproductive outcomes, while urban sparrows exhibited multiple significant effects of egg guarding on hatching success and hatchling guarding and food provisioning on fledging success. Our study emphasizes the need to identify environmental stressors that may affect behaviors associated with parental care in urban animals as well as the adaptive shifts they take to maintain nest success. Understanding urban stressors is critical for developing informed conservation strategies for commensal birds in a rapidly urbanizing landscape.

Habitat loss due to agricultural expansion is the primary threat to anurans worldwide. Where natural habitat is converted to monoculture, both anuran and prey diversity decline. Beyond species loss, land-use change disrupts species interactions and ecosystem functioning, making it essential to document how communities reorganize when natural habitats are replaced by agricultural systems. Here, we investigated how the intrusion of Eucalyptus silviculture into Brazil's Atlantic Forest impacts anuran communities, niche partitioning within them, and the structure of anuran–prey networks. Because Eucalyptus plantations are a biotically and structurally simplified environment, we predicted the abundance and diversity of anurans and prey, selectivity of anuran diets, and dietary niche partitioning among anuran species to be lower in Eucalyptus plantations, and we predicted the anuran–prey network in Eucalyptus would have a more connected, non-modular structure. We found that both anuran and prey abundance were lower in Eucalyptus plantations compared to neighboring Atlantic Forest fragments. Likewise, anuran diversity was also reduced in Eucalyptus, but prey diversity was similar between environments. Contrary to expectation, we found that dietary selectivity was not affected by land-use change and that niche partitioning and modularity were significant in the Eucalyptus community, whereas neither was significant for the Atlantic Forest community. These findings highlight how land conversion can significantly change the abundance and diversity of species, driving changes in community composition and organization.

Animals exhibit varying degrees of behavioral tolerance to anthropogenic noise. However, our understanding of how different species tolerate noise, and the specific behavioral consequences of noise exposure remains limited. We hypothesized that mantled howler monkeys (Alouatta palliata) show differential tolerance (i.e., likelihood to change their behavior) to different noise traits. We observed 18 adult subjects from two groups at Los Tuxtlas, Mexico, for 606 focal samples, recording 1488 noise events. Assessed noise traits were the number of noise occurrences, sound pressure level (SPL, measured with a sound meter), noise duration, and proximity to noise. The number of noises and SPL significantly increased the probability of activity change. Behavioral transition analysis revealed non-random patterns, with noise mostly disrupting rest-to-feed sequences while increasing move-to-feed transitions. The number of noises had the most consistent effects across behaviors, altering the activity budget for feeding, resting, locomotion, and vigilance. As the number of noises increased, feeding time rose from 9% to 14%, locomotion from 7% to 14%, and vigilance more than tripled from 2% to 7%, while resting declined from 80% to 63%. Increased noise duration resulted in decreased feeding (from 12% to 4%) but increased locomotion (from 7% to 15%). Thus, mantled howler monkeys exhibit a complex, trait-specific tolerance pattern to noise, showing greater sensitivity to the number of noises and noise intensity while potentially developing higher tolerance to duration and distance. These findings highlight the importance of implementing noise mitigation strategies in areas where wildlife interfaces with humans.