Another mystery solved for me. I had often wondered why some Ashy Prinia show supercilium and others don’t. Wikipedia informs me “In breeding plumage, adults of the northern population are ash grey above, with a black crown and cheek with no supercilium and rufescent wings. In non-breeding season this population has a short and narrow white supercilium and the tail is longer”
Psst… Supercilium is a synonym for eyebrow 😉