Ecological generalism and resilience of tropical island mammals to logging: A 23 year test

The distribution of bushmeat mammals in unflooded forests of the Central Amazon is influenced by poaching proxies

Medium to large rainforest mammals are key conservation flagship groups that offer non-redundant ecosystem functions, but anthropic pressures, such as illegal hunting, may strongly affect their occupancy in Amazonia. We combined camera traps and occupancy models to assess the influence of distance from human settlements, the number of families per settlement and the synergetic effect of the average weight of 27 species on the occupancy probability of mammals. Specifically, we classified mammal species according to the game preferences of hunters (i.e. a group of species depleted for bushmeat, a group of species hunted for retaliation and a group of non-hunted species). We also accounted for the influence on the detection probability of each group of both the number of days each camera operated and the body weight of mammals. The occupancy probability of the bushmeat group (i.e. deer, peccaries, agoutis, pacas and armadillos) was lower at locations closer to human settlements. Still, the number of families correlated positively with occupancy, with the occupancy probability of the group being slightly higher at sites with more families. This difference was probably due to larger and more abundant crops and fruiting trees attracting wildlife at such sites. Conversely, the occupancy probability of the retaliation group (i.e. carnivores) and the non-hunted group (i.e. opossums, spiny rats, squirrels and anteaters) were indifferent to anthropogenic stressors. The detection probability of the non-hunted and particularly the most depleted species correlated negatively with body weight. This may suggest that larger species, especially those from the bushmeat group, are rarer or less abundant in the system, possibly because they are the preferable target of hunters. In the long term, locals will likely need to travel long distances to find harvest meat. Poaching also threatens food security since game bushmeat is an essential source of protein for isolated rural Amazonians.

Vangunu giant rat (Uromys vika) survives in the Zaira Community Resource Management Area, Solomon Islands

Described in 2017 and known only from the holotype, Uromys vika is surely among the world's least studied rodents. This critically endangered species is facing a rapidly increasing scale for threat from logging of its primary lowland forest habitat, on the only island on which it occurs-Vangunu, Solomon Islands. However, a deep traditional ecological knowledge of U. vika is held by Vangunu's people. Using camera traps and guided by this knowledge, we aimed to make additional records of U. vika in the last major block of Vangunu's primary forest. We successfully captured 95 images of what we postulate is four different individuals. The forests at Zaira represent the last suitable habitat remaining for this species, and recent development consent for logging at Zaira will lead to its extinction if permitted to proceed.

An Indigenous perspective on the conservation of an insular endemic: the prehensile-tailed skink Corucia zebrata on the Solomon Islands

The prehensile-tailed skink Corucia zebrata is endemic to the Solomon Islands. It is the most traded reptile from the country. During 2000–2019, CITES reported the legal export of 10,567 individuals. Although the level of this trade is well documented, impacts on the skink's survival in its native range are comparatively unknown. During January–May 2020, we surveyed 146 people on 12 islands to collect information on the habitats preferred by the prehensile-tailed skink, to understand perceptions of the species' conservation status and identify any potential threats. Respondents reported lowland and hill forests as being favoured habitats, with low proportions of respondents identifying coastal and montane forests as suitable habitat. Habitat loss (72%), hunting (17%), and predation (6%) were identified as the main threats. People younger than 30 years of age reported killing the skinks more frequently than did people over the age of 30. Prehensile-tailed skinks have a relatively small home range, long reproductive cycle, and are vulnerable to numerous threats. We thus recommend a halt to the current practice of exporting wild-caught prehensile-tailed skinks, and replacement by a well-regulated captive breeding programme.

Late quaternary biotic homogenization of North American mammalian faunas

Biotic homogenization—increasing similarity of species composition among ecological communities—has been linked to anthropogenic processes operating over the last century. Fossil evidence, however, suggests that humans have had impacts on ecosystems for millennia. We quantify biotic homogenization of North American mammalian assemblages during the late Pleistocene through Holocene (~30,000 ybp to recent), a timespan encompassing increased evidence of humans on the landscape (~20,000–14,000 ybp). From ~10,000 ybp to recent, assemblages became significantly more homogenous (>100% increase in Jaccard similarity), a pattern that cannot be explained by changes in fossil record sampling. Homogenization was most pronounced among mammals larger than 1 kg and occurred in two phases. The first followed the megafaunal extinction at ~10,000 ybp. The second, more rapid phase began during human population growth and early agricultural intensification (~2,000–1,000 ybp). We show that North American ecosystems were homogenizing for millennia, extending human impacts back ~10,000 years.

Biotic homogenization, which is increased similarity in the composition of species among communities, is rising due to human activities. Using North American mammal fossil records from the past 30,000 years, this study shows that this phenomenon is ancient, beginning between 12,000 and 10,000 years ago with the extinction of the mammal megafauna.

Ecological dependencies make remote reef fish communities most vulnerable to coral loss

Ecosystems face both local hazards, such as over-exploitation, and global hazards, such as climate change. Since the impact of local hazards attenuates with distance from humans, local extinction risk should decrease with remoteness, making faraway areas safe havens for biodiversity. However, isolation and reduced anthropogenic disturbance may increase ecological specialization in remote communities, and hence their vulnerability to secondary effects of diversity loss propagating through networks of interacting species. We show this to be true for reef fish communities across the globe. An increase in fish-coral dependency with the distance of coral reefs from human settlements, paired with the far-reaching impacts of global hazards, increases the risk of fish species loss, counteracting the benefits of remoteness. Hotspots of fish risk from fish-coral dependency are distinct from those caused by direct human impacts, increasing the number of risk hotspots by ~30% globally. These findings might apply to other ecosystems on Earth and depict a world where no place, no matter how remote, is safe for biodiversity, calling for a reconsideration of global conservation priorities.