Ruth Walker: When an unwelcome intruder invades one's territory, animal instinct kicks in

THEY say one of the things that separates us from other species in the animal kingdom is our tendency to mate for life. No, hang on, that's not it. Wolves are big on the till-death-us-do-part thing too. As are gibbons, beavers and prairie voles, to name a few. And anyway, I'm not entirely convinced humans are particularly successful on that score.

So maybe it's our ability to empathise then, although there now seems to be evidence that creatures as tiny, smelly and scampery as mere mice can feel empathy for their fellow rodents.

Opposable thumbs? No, that's not it either. Nor is it the way we make and use tools, since capuchin monkeys, sea otters and even crows are now known to be an awful lot brighter than we once thought when it comes to adapting the objects around them for use in a specific task. Usually the gathering and devouring of food.

Olympia Dukakis proposed, in the film Steel Magnolias, that it was our ability to accessorise, though anyone who was brought up on the PG Tips adverts of the 1970s might disagree with that point of view too.

I suppose what I'm trying to say is this: we have an awful lot more in common with the animals that cohabit this Earth than we sometimes like to admit. Take our naturally territorial natures. We may not urinate or rub our glands around our driveways to keep the neighbours at bay (though I did once seriously consider sourcing lion excrement from Edinburgh Zoo in an attempt to halt the local urban fox family's indiscriminate feline killing spree), but we nevertheless guard our immediate surroundings with a ferocity that can be – if threatened – slightly alarming. According to Encyclopaedia Britannica, if the peeing doesn't discourage intruders, "chases and fighting follow".

Not, then, the kind of behaviour one might expect in one of the capital's better neighbourhoods (excellent school catchment, regular bus route into town, well-stocked corner shop, active neighbourhood watch, etc). But when an unwelcome intruder invades one's territory, animal instinct kicks in.

I have a driveway for a purpose: it is to park my car therein. As far as my neighbours are concerned, however, it has become a kind of Top Gear challenge to see who can park the closest; two cars on either side, one behind – the last time I was hemmed in like this it took half an hour and the aid of a passing jogger's increasingly impatient directions to release me.

Then last night, at approximately 1930 hours, the skirting of the Serengeti, the loud animal cries around the water hole, the arching of backs and flapping of feathers were upgraded to a full-on threat to the security of the lioness and her young: a silver Ford Fiesta parked right across the driveway.

I saw them doing it: two sweeet little old ladies with their bags of shopping, they seemed innocent enough, but their actions were a blatant call to war.

How rude! How disrespectful! How mean and calculated! I fumed through Poirot, twitching at the curtains during every ad break to see if the car was still there. It was, grille sneering at my obvious powerlessness to act. I tossed and turned through the night as I composed the polite (but with an underlying tone of menace) note I would leave on the windscreen. Perhaps I'd scratch it in blood. Or lion excrement. That would show them.

When I awoke in the morning, red-eyed and still tormented, I went straight to the window ready to exact my revenge. To my utter horror, the car had been moved.

It should have made me feel better – threat gone, yawning gap in the driveway, plenty room for manoeuvre – but, deprived of an outlet for my righteous indignation, I was incandescent with rage.

Twenty-four hours later, I am still on a high state of alert, constantly on the lookout for predators. It's a jungle out there.

This article was originally published in Scotland on Sunday on 28 February 2010