That's how Mike Bongiorno defined them in Sanremo, in 1966. By literally translating the band's name to "yard birds," he wanted to make the well-groomed and stiff audience of the festival smile by extending the term to "Gallinacci," since they hardly spoke a word of Italian... He, may his soul rest in peace, didn’t realize that "Yardbird" was the slang term for "prisoner" but also for "low-ranking soldier."
Well...

"We need to include 'For Your Love,' even though it was the over-commercialized song that made Clapton decide to leave them to secure a career rooted in the blues, which, in his view, the group was abandoning.... Here we see them with an unrecognizable Jeff Beck, somewhat subdued by having to simply accompany a song on acoustic guitar that, let's be honest, was just okay.... In a live version, he would have added an explosive solo, it’s clear... but here we are on TV...
The Yardbirds had much better arrows in their quiver....

The Yardbirds - For Your Love (1965) (Full version)