Potential millennial-scale avian declines by humans in southern China

Area of Science:

• Ecology
• Genomics
• Paleontology

Background:

• Observational data show recent human-caused faunal decline.
• Archaeological evidence suggests early human impact on biodiversity during the Holocene epoch.
• A key question is whether modern wildlife declines began with early human disturbance.

Purpose of the Study:

• To investigate if modern wildlife population declines originated during early human disturbance.
• To analyze the demographic history of six common East Asian forest birds.
• To assess the roles of climate change and human activities in past biodiversity changes.

Main Methods:

• Population genomic analysis of 25-33 genomes per species.
• Demographic history inference to reconstruct past population sizes.
• Ecological niche modeling to predict range shifts.
• Correlation analyses between population trends, climate variations, and human disturbance.

Main Results:

• Five of six bird species showed dramatic population declines (4- to 48-fold) thousands of years ago.
• Population declines did not correlate significantly with Holocene temperature changes.
• Ecological niche models predicted range persistence, indicating limited impact from climate change.
• Reconstructed population declines showed strong negative correlations with human disturbance intensities.

Conclusions:

• Early human activities, rather than Holocene climate change, are indicated as a primary driver of past bird population declines.
• These findings support the hypothesis of an early origin for human effects on biodiversity.
• The study provides a long-term perspective on the current biodiversity crisis and a framework for assessing human ecological impacts.