Dear Readers, when I was a child my Dad used to swear by something called Pepper Dust to keep the cats away from whatever it was that he’d just planted. You can still buy it, but what on earth is in it isn’t quite clear – I suspect cayenne pepper or something equally pungent. But does it work? Clearly, all those people investing in ultrasonic cat scarers and other devices think not.
I always love James Wong’s columns in New Scientist, for their good sense and scientific accuracy. First, he asks, why did capsaicin (the ‘hot’ part of chilli peppers) evolve in the first place? After all, chillies in their natural state are bright red and very attractive looking, so why would they want to deter the things that come to eat them? Well, chillies don’t ‘want’ just anything to eat them. Birds don’t have receptors for capsaicin, so they don’t get ‘burnt’, and when they eat the chilli peppers, the seeds pass through their bodies unharmed, and get transported elsewhere to germinate and create new chilli plants. Mammals, however, do have capsaicin receptors, and so dogs, cats, mice and deer learn to avoid the plants – the seeds are destroyed in the stomachs of these animals, so it’s of no benefit to the plant for them to be eaten.
Sayaca Tanager eating chillis (Photo By Alex Popovkin, Bahia, Brazil – Flickr: Sayaca Tanager feeding on malagueta peppers, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=17854806)
Should we be showering the garden with chilli, then? Wong points out that capsaicin is such a good deterrent for mice and rats that it’s often used in bird feed, poultry feed, and to protect the nests of rare ground-nesting birds. However, with larger mammals, the jury is out: badgers prefer food without chilli, but will eat it if there’s nothing else. Tough animals, badgers – they’ll dig up a bumblebee or wasp nest to get at the honey, so if they can tolerate being stung a bit of chilli-burn must be a walk in the park.
Wong points out, however, that chilli powder biodegrades, losing its ‘heat’ quickly. Also, just like humans, other animals can increase their tolerance for ‘the burn’. Wong recommends using the hottest chilli powder you can find, rotating it around the garden, replenishing it often, and keeping an eye on whether or not it’s effective.
You can read the whole article here. And in the meantime, Readers, do you use any kind of cat/fox/deer deterrent, and if so, what works for you?
When we first moved in last year, we had a few squirrels around the garden, but I think our dog, Tomos, has scared them off – at least a bit. My wife said she saw one outside the window last week, but I think that was an exception, which might prove the rule… 🤔
Small birds don’t seem to be deterred by his presence and he generally leaves them alone, but pheasants are another matter!
I don’t use this kind of deterrent (yet) but I’ve read that wasps hate cinnamon, so used that – not on a nest(!) but on fruit and suchlike around the garden to deter them. Not this year, though, as this was a strangely quiet year for the local wasps.