Suchergebnisse

Context West African crocodylian populations are declining and in need of conservation action. Surveys and other monitoring methods are critical components of crocodile conservation programs; however, surveys are often hindered by logistical, financial and detectability constraints. Increasingly used in wildlife monitoring programs, drones can enhance monitoring and conservation efficacy. Aims This study aimed to determine a standard drone crocodylian survey protocol and evaluate the drones as a tool to survey the diverse crocodylian assemblage of West Africa. Methods We surveyed crocodile populations in Benin, Côte d'Ivoire, and Niger in 2017 and 2018, by using the DJI Phantom 4 Pro drone and via traditional diurnal and nocturnal spotlight surveys. We used a series of test flights to first evaluate the impact of drones on crocodylian behaviour and determine standard flight parameters that optimise detectability. We then, consecutively, implemented the three survey methods at 23 sites to compare the efficacy of drones against traditional crocodylian survey methods. Key results Crocodylus suchus can be closely approached (>10 m altitude) and consumer-grade drones do not elicit flight responses in West African large mammals and birds at altitudes of >40–60 m. Altitude and other flight parameters did not affect detectability, because high-resolution photos allowed accurate counting. Observer experience, field conditions (e.g. wind, sun reflection), and site characteristics (e.g. vegetation, homogeneity) all significantly affected detectability. Drone-based crocodylian surveys should be implemented from 40 m altitude in the first third of the day. Comparing survey methods, drones performed better than did traditional diurnal surveys but worse than standard nocturnal spotlight counts. The latter not only detected more individuals, but also a greater size-class diversity. However, drone surveys provide advantages over traditional methods, including precise size estimation, less disturbance, and the ability to cover greater and more remote areas. Drone survey photos allow for repeatable and quantifiable habitat assessments, detection of encroachment and other illegal activities, and leave a permanent record. Conclusions Overall, drones offer a valuable and cost-effective alternative for surveying crocodylian populations with compelling secondary benefits, although they may not be suitable in all cases and for all species. Implications We propose a standardised and optimised protocol for drone-based crocodylian surveys that could be used for sustainable conservation programs of crocodylians in West Africa and globally.

Despite being heavily exploited, pangolins (Pholidota: Manidae) have been subject to limited research, resulting in a lack of reliable population estimates and standardised survey methods for the eight extant species. Camera trapping represents a unique opportunity for broad-scale collaborative species monitoring due to its largely nondiscriminatory nature, which creates considerable volumes of data on a relatively wide range of species. This has the potential to shed light on the ecology of rare, cryptic and understudied taxa, with implications for conservation decision-making. We undertook a global analysis of available pangolin data from camera trapping studies across their range in Africa and Asia. Our aims were (1) to assess the utility of existing camera trapping efforts as a method for monitoring pangolin populations, and (2) to gain insights into the distribution and ecology of pangolins. We analysed data collated from 103 camera trap surveys undertaken across 22 countries that fell within the range of seven of the eight pangolin species, which yielded more than half a million trap nights and 888 pangolin encounters. We ran occupancy analyses on three species (Sunda pangolin Manis javanica, white-bellied pangolin Phataginus tricuspis and giant pangolin Smutsia gigantea). Detection probabilities varied with forest cover and levels of human influence for P. tricuspis, but were low (<0.05) for all species. Occupancy was associated with distance from rivers for M. javanica and S. gigantea, elevation for P. tricuspis and S. gigantea, forest cover for P. tricuspis and protected area status for M. javanica and P. tricuspis. We conclude that camera traps are suitable for the detection of pangolins and large-scale assessment of their distributions. However, the trapping effort required to monitor populations at any given study site using existing methods appears prohibitively high. This may change in the future should anticipated technological and methodological advances in camera trapping facilitate greater sampling efforts and/or higher probabilities of detection. In particular, targeted camera placement for pangolins is likely to make pangolin monitoring more feasible with moderate sampling efforts. (c) 2019 The Authors. Published by Elsevier B.V. ; Fondation Segr~e; Biodiversity Monitoring Centre (Centre de Surveillance de la Biodiversit ~e) at the Faculty of Sciences of the University of Kisangani; Centre for International Forestry Research (CIFOR); Department of Science and Technology, Government of India (DST)Department of Science & Technology (India) [SR/S0/AS-100/2007]; Ministry of Education MalaysiaMinistry of Education, Malaysia [NRGS 2013/1088/02]; U.S. National Science FoundationNational Science Foundation (NSF) [BCS 1266389]; AXA Research Fellowship; Gordon and Betty Moore FoundationGordon and Betty Moore Foundation ; Thank you to the many individuals and institutions who generously made their data available for this study, and to the Zoological Society of London and donors to the IUCN SSC Pangolin Specialist Group for supporting the time of HK and CB during their research internships. The authors are grateful to Fondation Segr~e for supporting this research. AL would like to thank the Biodiversity Monitoring Centre (Centre de Surveillance de la Biodiversit ~e) at the Faculty of Sciences of the University of Kisangani and the Centre for International Forestry Research (CIFOR) for financial, academic and logistical support. AM would like to thank Agence Nationale des Parcs Nationaux and Centre National de la Recherche Scientifique et Technologique for kindly granting permission to conduct research in Gabon. CKO and TB would like to thank the Nouabal~e-Ndoki Foundation and Ministry of Forest Economy, Republic of Congo for kindly providing research permissions. GVG would like to gratefully thank the Department of Science and Technology, Government of India for their funding (DST. No. SR/S0/AS-100/2007), Mr. K. M. Selvan and Mr. S. Lyngdoh for their support in field data collection, and the Department of Environment & Forest, Government of Arunachal Pradesh for permissions. JAMwas supported by Ministry of Education Malaysia (NRGS 2013/1088/02). LAI acknowledges support from the U.S. National Science Foundation (BCS 1266389). ORW was supported by an AXA Research Fellowship. SE would like to thank R. Mueller and R. Roder for their input into data processing. Some data in this publication was provided by the Tropical Ecology Assessment and Monitoring (TEAM) Network, a collaboration between Conservation International, the Smithsonian Institution, and the Wildlife Conservation Society, and partially funded by these institutions, the Gordon and Betty Moore Foundation, and other donors.