Pair-bonded Java sparrows show enlarged eye rings to signal breeding readiness. Birds are known for their elaborate courtship rituals and romantic gestures that are replete with beautiful songs ...

Pair-bonded Java sparrows show enlarged eye rings to signal breeding readiness. Birds are known for their elaborate courtship rituals and romantic gestures that are replete with beautiful songs ...

As youngsters, Ari and Junianto would clamber over the upland above Sambirata village, gathering sap to glue-trap the birds ...

Biting hard or singing fast? In my research, I work with Java sparrows and domestic canaries. The bite of the former is more than three times stronger than that of the latter.

Java sparrows (left) have much bigger and stronger beaks than canaries (right), but sing fewer syllables per second. Photos by Jeffry Surianto and Rodrigo Chaves from Pexels. Song spectrograms ...