My kids asked the other day, “why do deer have white bums?”. I had a vague idea it was related to warning, or escaping from danger. I told them deer raise their tail when alarmed, letting the rest of the herd know that there is something to worry about – I did make a mental note to check my facts later.

The red deer seem close and fearless now. Not in the bold and belligerent manner they have during rutting season – more like they see us, but don’t care. Two in the field by the house nudge their way across the boggy ground towards better grazing: a stag with short black antler furred with regrowth, and a golden-backed hind. When I walk closer, they only lift their heads, briefly returning my look, and return to browsing.

However, they view our jumpy 4-month-old collie differently. The same pair were cruising slowly into the woodland near the top of the hill as I walked up behind them with the dog. When we reached the outer birch trees, the deer had moved out of sight. But the puppy stopped stock-still, nose pointed towards the space where they had been. Just as I asked her what else she saw (in the way we do with puppies and babies, not really expecting an answer), she yapped loudly, sending me out of my skin.

At the dog’s bark, the two deer appeared from behind a clump of hazel – except it wasn’t two at all. Their light rumps were revealed as they turned away from us, picking up speed as their heavy brown bodies bobbed lightly over the fence, then two more, then more again began to flow up the hill; a paper chain of pale hearts, disappearing into the trees.

In the Forward to Understanding Animal Behaviour (Whittles Publishing, 2019), Rory Putman says that he is writing for amateur naturalists like myself. Following the recommendation of a friend, I turned to the book to ask if Putman could shed any light on my very loose conclusions about the deer behaviour. Sure enough, he observes that many social mammals have developed calls or actions ‘which ‘warn’ other members of the group or feeding assemblage of potential danger and allow them to take some evasive action’. He talks about roe deer fluffing up ‘the hair of their white rump patch into an extremely obvious ‘powder-puff if they scent or see a predator’ then running off. Or the African springbok, ‘who flare their magnificent white rump patch and make a series of high leaps into the air, ‘pronking’ ostentatiously as they run.’

The roundish white rear-ends of red deer appear a little like easily tracked target; it seems contradictory that they evolved in defence. Putman suggests it is altruistic, one for the good of the herd: ‘…behaviour which advertises the presence of the predator to other must act, quite by reverse, to draw attention to yourself, while allowing others to escape.’

Standing at the bottom of the hill, I caught only glimpses of those pale rumps before they vanished completely. To the following herd, they may have been as bright as airport landing lights – this way to safety.

First published in Lochaber Times 27th May 2022