On the margins of the Forest you should be able to hear the rusty hinge call of the Great Tit, Parus major, Mésange charbonnière or Koolmees. The classic phonetic rendering is “tea-cher, tea-cher, tea-cher”, but it has a much wider repertoire, with subtle variations abounding. There is a link to a YouTube video if you want a listen.
Beau Geste? Perhaps you have seen the film in which three brothers defend a desert fort against a far more numerous enemy. To confound their attackers, they prop up the bodies of their fallen comrades to make the fort appear more forbidding.
In the 1970s, John Krebs proposed a theory that Great Tits do something similar, but through song. By having several song variations under their wing, they try to make it sound as though an area is more densely populated by rivals, in order to discourage any prospective invaders.
In the United States, tits are known as titmice, with UK English having dropped the original “mouse”. Despite appearances, this has nothing to do with rodents. It comes from Old English and Germanic roots, with “tit” meaning something small, think of a “titbit”, a morsel of food, and mase or mose meaning “bird”. So the Great Tit is, linguistically at least, a large little bird. The Dutch suffix mees comes from the same root.