Avian colouration in a polluted world: a meta-analysis

Area of Science:

• Ornithology
• Ecology
• Environmental Science

Background:

• Avian colouration plays roles in sexual selection, thermoregulation, and predator avoidance.
• Sexually selected traits, like vibrant bird ornaments, are hypothesized to be sensitive indicators of environmental quality.
• Anthropogenic pollution's effects on these traits have been increasingly studied over the past two decades.

Purpose of the Study:

• To conduct the first meta-analysis on the impact of anthropogenic pollution on avian colouration.
• To investigate interactions between pollution type and colour production mechanisms (carotenoid, melanin, structural).
• To test if sexually selected ornaments in males are more sensitive to pollution.

Main Methods:

• Meta-analysis of existing studies on anthropogenic pollution and avian colour traits.
• Categorization of pollutants (heavy metals, persistent organic pollutants, urbanisation, other).
• Examination of colour production mechanisms and sex-specific sensitivities.

Main Results:

• A significant negative overall effect size indicates detrimental impacts of pollution on avian colouration.
• Carotenoid-based colouration was most sensitive to anthropogenic disturbances.
• No significant interaction between pollution type and colour mechanism, nor heightened sensitivity in males was found.
• A notable research gap exists for structural colouration.

Conclusions:

• Anthropogenic pollution poses a general threat to avian colouration, with carotenoid-based colours being particularly vulnerable.
• Future research should prioritize structural colouration and employ standardized methods for colour quantification.
• Avian colour traits, especially carotenoid-based ones, can serve as indicators of environmental quality.