Survey-based inference of continental African elephant decline

• 成果类型: Article
• 署名作者: Edwards, Charles T. T.; Gobush, Kathleen S.; Maisels, Fiona; Balfour, Dave; Taylor, Russell; Wittemyer, George
• 署名单位: University of Washington; University of Washington Seattle; Wildlife Conservation Society; University of Stirling; Nelson Mandela University; Colorado State University System; Colorado State University Fort Collins
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-15095
• DOI: 10.1073/pnas.2403816121
• 发表日期: 2024-11-26
• 关键词: extinction risk; ivory trade; TRENDS

摘要

of conservation status, which in turn is critical for planning and targeting management interventions. However, monitoring effort and methodologies can change over the assessment period, resulting in heterogeneous data that are difficult to interpret. Here, we develop a hierarchical, random effects Bayesian model to estimate sitelevel trends in density of African elephants from geographically disparate survey data. The approach treats the density trend per site as a random effect and estimates a parametric distribution of these trends for each partitioning of the data. Data were available from 475 sites, in 37 countries, between 1964 and 2016 (a total of 1,325 surveys). We implemented the model separately and in combination for the African forest (Loxodonta cyclotis) and savannah (Loxodonta africana) elephant species, as well as by region. Inference from these distributions indicates a mean site-level decline for each species over the study period, with the average forest elephant decline estimated to be more than 90% compared to 70% for the savannah elephant. In combination, there has been a mean 77% decline across all sites; but in all models, substantial heterogeneity elephant species, illustrating the variability in their status across populations.