What does Kevin in Home Alone have in common with a Great Tit?

Macauley Culkin with spirit animal, Parus Major

There is a rule of among seasoned bird-listeners: if you can’t tell what it is, it’s probably a Great Tit.

As well as their signature ‘squeaky bicycle pump’ tune, Great Tits deliver a bewildering array of songs and calls. Some of these are subtle variations on the mechanical two-tone theme, while others sound totally different. To confuse matters further, Great Tits are also accomplished mimics of completely different species. 

But why? One idea is the ‘Beau Geste hypothesis’. 

Beau Geste is a 1924 novel, much filmed and parodied since, in which a desert fort is defended by a small but determined group of soldiers. One of their tactics is to prop up the bodies of their fallen comrades and make the base appear better defended than it is. 

Macauley Culkin applies the same idea to protect his house from Joe Pesci* in Home Alone.

The ornithological hypothesis is that Great Tits do something similar.

By putting up such a varied vocal performance, they’re making their territory seem fuller than it really is, and putting off other birds (specifically, other male rivals) from establishing themselves. 

Studies have confirmed that Great Tits with wider repertoires are more successful overall, although there’s some uncertainty about whether this is the secret of their success, or a correlation - i.e. more successful birds tend to develop these skills along the way.  

What's beyond doubt is that Great Tits are highly successful at bamboozling human ears. They do plenty of that from late winter, through the spring and into the summer.

Listen to a variety of Great Tit noises over on Shriek of the Week

* For anyone arriving here from the search term ‘danny devito home alone’ - the actor playing Kevin’s nemesis Harry was, of course, Joe Pesci. The text has been corrected.

Harry: Why the hell did you take your shoes off?
Marv: Why the hell are you dressed like a chicken?