Global abundance estimates for 9,700 bird species

Area of Science:

• Ecology
• Evolutionary Biology
• Conservation Science

Background:

• Species abundance quantification is crucial for ecological, evolutionary, and conservation studies.
• Global patterns of species abundance remain largely unresolved due to data heterogeneity and limited scalable methods.
• Existing data primarily characterizes a few species well, leaving most poorly understood.

Purpose of the Study:

• To develop a scalable method for estimating global species-specific abundances and their uncertainty.
• To resolve the empirical pattern of species abundance distribution at a global scale.
• To provide a foundation for analyzing abundance structures across biogeographic and ecological contexts.

Main Methods:

• Integration of data from well-studied species with a global bird occurrence dataset (9,700 species, ~92% of extant species).
• Application of missing data theory to estimate species-specific abundances and associated uncertainties.
• Aggregation of species-level estimates to determine global abundance patterns.

Main Results:

• Strong evidence for a log left-skewed distribution of species abundances, indicating numerous rare species and fewer common species.
• Estimation of approximately 50 billion individual birds globally.
• Demonstration of a repeatable and scalable methodology for abundance quantification.

Conclusions:

• The developed method provides a robust framework for estimating global species abundance with uncertainty.
• Findings offer insights into the structure of abundance across realms and guilds, and life history consequences.
• The methodology is adaptable for quantifying abundance in other organisms, enhancing biodiversity tracking.