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Updated: Jun 7, 2025
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Protocol for Assessing the Relative Effects of Environment and Genetics on Antler and Body Growth for a Long-lived Cervid
Published on: August 8, 2017
7.3K
Survey-based inference of continental African elephant decline
Charles T T Edwards1, Kathleen S Gobush2, Fiona Maisels3,4
1CEscape Consultancy Services, Knysna 6570, South Africa.
Summary
African elephant populations show significant declines, with forest elephants experiencing over 90% reduction and savannah elephants over 70%. This comprehensive study highlights regional variations in elephant population trends.
Area of Science:
- Ecology and Conservation Biology
- Wildlife Population Dynamics
- Statistical Modeling in Ecology
Background:
- Long-term species trend quantification is crucial for conservation status assignment and management interventions.
- Heterogeneous monitoring data due to changing methodologies pose challenges for accurate trend interpretation.
- Understanding population dynamics is vital for effective conservation of African elephant species.
Purpose of the Study:
- To develop a robust statistical model for estimating site-level density trends of African elephants using disparate survey data.
- To quantify long-term population trends for both African forest (Loxodonta cyclotis) and savannah (Loxodonta africana) elephants.
- To assess the variability in population status and trends across different regions and species.
Main Methods:
- Development of a hierarchical, random effects Bayesian model to analyze geographically dispersed survey data.
- Estimation of site-level density trends, treating each site's trend as a random effect.
- Implementation of the model separately and in combination for forest and savannah elephants, and by region, using data from 475 sites across 37 countries (1964-2016).
Main Results:
- Inference indicates a mean site-level decline for both African forest and savannah elephants over the study period.
- Average forest elephant decline estimated at over 90%, and savannah elephant decline at over 70%.
- A combined mean decline of 77% across all sites was observed, with significant heterogeneity in trends, particularly stable to increasing trends in southern Africa.
Conclusions:
- This study provides the most comprehensive assessment of African elephant population trends to date.
- Significant population declines necessitate urgent conservation attention, with varying impacts across species and regions.
- The developed Bayesian modeling approach effectively handles heterogeneous data to provide reliable trend estimates for conservation planning.
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