When kestrels turn pale: What colour tells us about bird health in human-dominated landscapes

(by Petra Sumasgutner)

Kestrel chicks in urban centres are paler than their brightly yellow-and orange coloured rural conspecifics, and show lower blood levels of antioxidants (circulating carotenoids). Both indicate that urban food webs are poor in carotenoids, starting with plants - caterpillars - birds and rodent prey - and accumulating in kestrels. In intensively farmed areas of Finland, food shortages during a low vole year revealed striking sex differences: females with higher genetic diversity were brighter and less infected by parasites, while males in better body condition were those specialising on voles, independent of their genetic diversity. Together, these findings show that kestrel colouration is a sensitive indicator of health and environment, and that this species can act as a sentinel for how urbanisation and agricultural intensification impact wildlife.

👉 Read the full story in the BOU Blog https://bou.org.uk/blog-sumasgutner-when-kestrels-turn-pale/

credit: Johannes Ploderer