Experts are often incensed by mistakes in fiction. In his hateful little book, Lord of the Flies, William Golding famously made Piggy short-sighted, only to have him light a fire with his glasses! Like duh! As any physicist will tell you he'd have needed long-sighted lenses. Every time a coma patient wakes up to a zombie apocalypse and rips the intravenous drip from their arm, a thousand nurses scream 'do you know how long that cannula is?' And if Thames Valley Police really solved crimes by pontificating their way around the pubs, colleges and other landmarks of Oxford, we really would be living in the murder capital of England.
As an ex-ecologist my pet annoyance is monsters. In particular, the way in which monsters always announce themselves with a blood-curdling roar. So prevalent is this cliche that its hard to think of a Hollywood monster movie in which it doesn't occur. Jurassic Park, Avatar, Life of Pi, Alien (actually, that's more of a blood-curdling hiss) - I could go on.
Now as any biologist will tell you, and as anyone who's ever watched any nature programme will concur, predators do not announce themselves to their prey. The moment you know a jaguar is after you is when it lands on your head. Any lion that gave a herd of wilderbeest a blood-curdling roar would be a very hungry lion indeed. Every time it happens in a movie, therefore, I find my annoyance levels rising. (And don't get me started on the ecology of Alien - I mean a predator/parasitoid would go extinct rather quickly - didn't anyone think about this stuff?).
No, the only time predators roar is when they're fighting each other, or, more strictly speaking, when they're trying not to fight each other. Here, the blood-curdling roar is a handy non-contact way of saying 'I could have you.' Much less costly than actually having to fight.
Now before you accuse me of missing the point entirely, no one has ever let the facts get in the way of a good story, nor should they. Fiction is fiction and monsters are not predators: they're monsters. As such they're human projections, our worst nightmares made flesh. No wonder that they behave like humans. The blood-curdling roar is just movie shorthand for 'I could have you', or worse, that 'I'm coming to get you.' Horrible.
Who doesn't remember the roar of the ogre in Jack and the Beanstalk?
Fee, fi, fo, fum
I smell the blood of an Englishman
Be he alive or be he dead
I'll grind his bones to make my bread.
It terrified me in childhood and chills me to this day, even if bakers everywhere are clenching their floury fists and muttering darkly "that bread'll never rise."