No abstract

Nest‐site selection exerts a fundamental maternal effect on offspring fitness in oviparous species. In many freshwater turtles, females do not care for their eggs after oviposition but rather rely on a nest's micro‐environment to incubate developing embryos although linkages between oviposition choices and overall fitness remain poorly evaluated. We tested predictions derived from multiple hypotheses to examine nesting patterns of the yellow‐spotted river turtle Podocnemis unifilis, a species imperiled by egg harvesting by humans throughout its range, based on data collected from 73 nesting sites along 118 km of river in the eastern Brazilian Amazon. Nesting area size largely explained nest‐site selection by turtles, but only weakly explained turtle egg harvesting by humans. Despite the wide availability of alternative nesting habitats, turtles do not appear to be capable of avoiding hazardous nesting sites associated with increased egg harvesting by humans. Because signals used by female turtles to select nesting areas are apparently not sufficient for avoiding nesting along rivers accessible to humans, direct conservation action will be vital for persistence of these and likely other Amazonian freshwater turtles.

Substrate type determines nesting success and fitness in turtles and is a critical consideration for nesting area protection and restoration. Here, we evaluated the effect of substrate on nest removal by humans in the eastern Brazilian Amazon. We analyzed substrate composition and fate of 216 P. unifilis nests along 88 km of rivers. River segment and substrate type were the most important predictors of nest removal by humans. We found up to 36% lower removal of nests in fine sand and experimental results support the hypothesis that wind more often obscures tracks of nesting females in substrates with more (>66%) fine sand. Our findings are useful for informing the restoration of artificial nesting areas across the Amazon, as nesting area substrates should be selected not only to maintain hatchling sex ratios, but also to minimize nest removal by humans. Turtles are experiencing global population declines 1 , with approximately 61% of all species threatened with extinction or already extinct 2. This issue is particularly acute in the tropics, where turtles represent food and income for local populations 1,3-5. Survival of exploited turtle populations can be enhanced by habitat restoration 6-8. For example, increasing available nesting habitat improved population growth in threatened marine turtles 9,10 and recruitment in temperate freshwater turtles 11,12. In contrast, the restoration of terrestrial nesting habitats for tropical freshwater turtles remains poorly explored. The Amazon basin encapsulates 21 st century conservation challenges for tropical freshwater turtles. Myriad threats to species and populations mean that the priorities for freshwater turtle conservation actions remain intensely debated 13. Among the factors affecting long-term turtle population viability, adult survival has been demonstrated to be crucial 14,15 , but nest-site selection by female turtles is also a key process for reproductive success and maternal survival 16-18. The once common freshwater turtles (Podocnemis spp.) are declining across Amazonia due to rampant overexploitation of both adults and eggs 19,20 , and the loss and degradation of aquatic (feeding, dispersal and reproduction) and terrestrial (nesting) habitat due to deforestation 21 and hydroelectric expansion 19. Additionally, as with many wildlife species across Amazonia, the lack of effective enforcement of existing regulations 22,23 and ineffective environmental impact assessments 22,24,25 mean that conservation actions have failed to generate widespread recoveries 5,26. Currently, the yellow-spotted river turtle (Podocnemis unifilis) is classified as Vulnerable (A1acd) by the IUCN 27 , with a recommended revision to Endangered 5. P. unifilis is a widespread freshwater species found across the Amazon, North Atlantic and Orinoco river basins 27,28. This is a relatively large species (females can weight up to 12 kg) that has been exploited since the pre-colonial period (pre 18th century) and is still widely consumed by indigenous and riverine peoples across Amazonia 4,20...

The global expansion of road networks threatens apex predator conservation and ecosystem functioning. This occurs through wildlife-vehicle collisions, habitat loss and fragmentation, reduced genetic connectivity and increased poaching. We reviewed road impacts on 36 apex predator species and assessed their risk from current roads based on road exposure and species vulnerability. Our findings reveal all apex predators are exposed to road impacts. Eight of the ten species with the highest risk occur in Asia, although other high-risk species are present in the Americas, Africa and Europe. The sloth bear suffers the highest risk of all apex predators, followed by the tiger and dhole. Based on species risk from roads, we propose a widely applicable method to assess the potential impact of future roads on apex predators. We applied this method to proposed road developments in three areas: the Brazilian Amazon, Africa, and Nepal, to locate high-impact road segments. Roughly 500 protected areas will be intersected by these roads, threatening core apex predator habitats. We advocate the need for rigorous road development planning to apply effective mitigation measures as an urgent priority and to avoid construction in wilderness areas and predator strongholds.

No abstract

Sustainable wildlife management is required to guarantee source species viability; however, it is practiced rarely in the tropics. The yellow anaconda (Eunectes notaeus) has a long history of being harvested for its leather. Since 2002 its harvest has operated under a management program in northeastern Argentina, which relies on adaptive management through limiting the minimum anaconda length, number of hunters and restricting the hunting season. We investigated the effects of the anaconda harvest on its biological parameters based on 2002-2016 data. Here we show that the levels of species exploitation are sustainable. The gradual reduction in the annual hunting effort, due to a decrease in number of hunters and hunting season duration, reduced the total number of anacondas harvested. Conversely, captures per unit effort increased across the study time-period. There was no variation in the mean length of anacondas harvested, or in largest anaconda sizes. Though more females than males were caught, the sex ratio did not vary significantly. We also found that a decrease in mean temperature positively influenced anaconda harvest and the captures of giant individuals. Because sustainable use is a powerful tool for conservation, those discoveries are highly applicable to other species and regions.

Sustainable wildlife management is necessary to guarantee the viability of source populations; but it is rarely practiced in the tropics. The yellow anaconda (Eunectes notaeus) has long been harvested for its leather. Since 2002 its harvest has operated under a management program in northeastern Argentina, which relies on adaptive management practices, that limit the minimum body length permitted for harvesting, the number of active hunters and the length of hunting seasons. Here we investigated the effects of yellow anaconda harvest on its demography based on 2002–2019 data and show that exploitation levels are sustainable. The gradual reduction in annual hunting effort, due to a decrease in the number of hunters and hunting season duration, reduced the total number of anacondas harvested. Conversely, captures per unit effort increased across the study period. The body size of anacondas was not influenced by the harvesting, and more females than males were caught. We also found that a decrease in mean temperature positively influenced anaconda harvest and the capture of giant individuals. Because sustainable use is a powerful tool for conservation, and anacondas are widespread in South America, these discoveries are highly applicable to other species and regions.

Though recent research has explored the negative impact of human infrastructure on large waterbirds, few studies have examined behavioural byproducts such as roosting or nesting on transmission wires. Here, we document our observation of a joint roost of White-breasted Cormorant Phalacrocorax lucidus and African Darter Anhinga rufa on transmission lines in the Western Cape, South Africa. We highlight current gaps in understanding communal roosting, joint roosts between species, and roosting on infrastructure, and provide recommendations for future directions of study.