To address the ongoing debate over the impact of invasive species on native terrestrial wildlife, we conducted a large-scale experiment to test the hypothesis that invasive Burmese pythons (Python molurus bivittatus) were a cause of the precipitous decline of mammals in Everglades National Park (ENP). Evidence linking pythons to mammal declines has been indirect and there are reasons to question whether pythons, or any predator, could have caused the precipitous declines seen across a range of mammalian functional groups. Experimentally manipulating marsh rabbits, we found that pythons accounted for 77% of rabbit mortalities within 11 months of their translocation to ENP and that python predation appeared to preclude the persistence of rabbit populations in ENP. On control sites, outside of the park, no rabbits were killed by pythons and 71% of attributable marsh rabbit mortalities were classified as mammal predations. Burmese pythons pose a serious threat to the faunal communities and ecological functioning of the Greater Everglades Ecosystem, which will probably spread as python populations expand their range.

Aim Our understanding of the effects of invasive species on faunal diversity is limited in part because invasions often occur in modified landscapes where other drivers of community diversity can exacerbate or reduce the net impacts of an invader. Furthermore, rigorous assessments of the effects of invasive species on native communities that account for variation in sampling, species-specific detection and occurrence of rare species are lacking. Invasive Burmese pythons (Python molurus bivittatus) may be causing declines in medium-to large-sized mammals throughout the Greater Everglades Ecosystem (GEE); however, other factors such as urbanization, habitat changes and drastic alteration in water flow may also be influential in structuring mammal communities. The aim of this study was to gain an understanding of how mammal communities simultaneously facing invasive predators and intensively humanaltered landscapes are influenced by these drivers and their interactions.Location Florida, USA.Methods We used data from trail cameras and scat searches with a hierarchical community model that accounts for undetected species to determine the relative influence of introduced Burmese pythons, urbanization, local hydrology, habitat types and interactive effects between pythons and urbanization on mammal species occurrence, site-level species richness, and turnover.Results Python density had significant negative effects on all species except coyotes. Despite these negative effects, occurrence of some generalist species increased significantly near urban areas. At the community level, pythons had the greatest impact on species richness, while turnover was greatest along the urbanization gradient where communities were increasingly similar as distance to urbanization decreased.Main conclusions We found evidence for an antagonistic interaction between pythons and urbanization where the impacts of pythons were reduced near urban development. Python-induced changes to mammal communities may be mediated near urban development, but elsewhere in the GEE, pythons are likely causing a fundamental restructuring of the food web, declines in ecosystem function, and creating complex and unpredictable cascading effects.

Habitat loss and degradation can undermine wildlife communities and ecosystem functioning. However, certain generalist wildlife species like mesopredators and omnivores can exploit these disturbed habitats, sometimes leading to population increases (e.g. ‘mesopredator release’ in degraded areas). Although mesopredator release may cause negative effects on food webs and zoonotic disease management, some disturbance‐tolerant species may help perpetuate important ecological interactions, such as seed dispersal. We evaluated the habitat associations of common palm civets Paradoxurus hermaphroditus, which are widespread generalist mesopredators in Southeast Asia. Common palm civets are also high‐quality seed dispersers, and potential zoonotic disease hosts. We used published and new camera trapping data to map their probability of presence across Southeast Asia and evaluate regional‐scale associations between capture rates and habitat variables such as elevation, ecoregion intactness and Human Footprint Index, among others. We also assessed the influence of habitat variables on their relative abundance at the local scale. At the regional scale, we found that common palm civets showed significant positive associations with landscapes characterized by lower ecoregion intactness, higher Human Footprint Index and lower elevations. At the local scale, their relative abundance showed a significant positive association with higher Human Footprint Index, but only to a certain point, after which it started decreasing. They also favoured lower elevations at the local scale. These multi‐scale results indicate that common palm civets' abundance can increase under certain levels of human disturbances, consistent with the ‘mesopredator release’ hypothesis. This suggests they may be crucial seed dispersers in degraded forest landscapes, especially where more sensitive seed dispersers have disappeared. Our results are also consistent with previous studies reporting that habitat degradation increases populations of potential zoonotic disease hosts, and thus risks of transmission to humans.

No abstract

No abstract