Eurasian songbirds’ singing while wintering in Africa

This video shows a great reed warbler singing.

From The American Naturalist in the USA:

Why do migratory birds sing on their tropical wintering grounds?

Migratory songbirds may sing during the winter months to improve their song quality ahead of the springtime mating season

Marjorie C. Sorensen, Claire N. Spottiswoode, and Susanne Jenni-Eiermann

The first notes of bird song signal the arrival of spring as well as the beginning of mate attraction season, and for many songbird species males with the most elaborate songs do best when it comes to attracting females. But why do many migratory songbirds sing during the winter, when they are thousands of kilometers away from their breeding grounds and the prospect of attracting a mate? This was the long-unanswered question tackled by Marjorie Sorensen, Susanne Jenni-Eiermann, and Claire Spottiswoode.

To answer this question, the researchers test three hypotheses to explain why winter singing might benefit