As much as I enjoy “squirrel parkour” around my birdfeeder on a daily basis, sometimes both myself and the birds need a break. My birdfeeder was being emptied every two days, and the birds would retreat quickly whenever a squirrel rushed the feeder. I took to alternating between cracked sunflower seeds (which everyone loves) and safflower seeds (which squirrels won’t eat unless they are starving). At one time I got curious about the pepper-laced seeds and logs since they were promoted as a food source that birds would eat but squirrels and other mammals (like raccoons) would not.
It’s very true that the squirrels want nothing to do with anything doused with capsaicin (hot peppers), which causes the “heat” you feel when you’ve eaten anything exceedingly hot. The burning sensation is likely a plant defence that occurs when capsaicin tricks your body into thinking it’s experiencing a real burn.
Ecologically, capsaicinoids may function to protect the seeds within the fruit. They may also influence seed dispersal patterns by influencing gut retention times of the seeds, resulting in more successful plant reproduction.
Research has shown that only mammals have receptors for capsaicin (it’s a mammalianTRPV1 agonist) while birds do not, so they are thought to be unaffected by consuming pepper-laced foods. Scientists have isolated the VR1 receptor in birds and found that capsaicin does not bind to it, thus it does not produce a painful sensation (at least not when eaten – it’s uncertain what happens if it comes into contact with their eyes).
Birds did eat the pepper-laced seeds and logs, but I noticed it took a really long time for them to be consumed. Also noteworthy is the fact that the pepper-laced peanut logs eventually fell apart and onto the ground, where no one seemed to eat them. If they had not been of the pepper-laced variety, squirrels would have cleaned this up in short order. Eventually I picked up what was left and threw it away, because I was concerned the pepper particles would contaminate the ground and when small animals rooted around, they might get their eyes irritated.
The more I thought about this possibility, I began to wonder what might be the unintended consequences of using capsaicin on other animals and insects. Even if birds were not affected in any way, is this an equitable feed to provide? Can dogs be harmed if they root around in the fallen peanut logs? Is it better to alternate foods or reduce foods that squirrels eat, rather than put this potential irritant out where susceptible animals come in contact with it?
Some organizations, such as Cornell’s Lab of Ornithology, which operates the backyard citizen-based Project FeederWatch, have expressed concern about offering birds spiced-up food and recommend that we don’t use it.
The Audubon Society had this to say about hot pepper products….
“Use no additives in seed or nectar. Capsicum [the genus for hot peppers] irritates the eyes of humans and is likely to do so with birds as well. We do not recommend adding capsicum to bird seed.”
“There really haven’t been any scientific studies on whether the hot pepper extract, capsaicin, is harmful to the animals’ eyes. It does deter squirrels from eating seed. The nerve receptor in mammals that is triggered by capsaicin, however, is apparently not activated in birds; and, therefore, the mucous membranes in the gastro-intestinal system of birds ingesting capsaicin are not irritated. This might be the same for their eyes, but that is not clear from the scientific literature. Capsaicin is deadly to bees and other beneficial pollinators, so that is not something we promote spraying around our yards as an insecticide.”
Capsaicin has a technical fact sheet on the National Pesticide Information Center website.
“Capsaicin is an animal repellent that has also been registered for use as an insecticide, miticide, rodenticide, and feeding depressant.”
USES:
“Capsaicin is used on vegetation such as crops and trees, buildings, and garbage containers. It is registered to repel vertebrate pests such as rabbits, squirrels, deer, voles, raccoons, cats, dogs, and skunks. It is also used as an attack deterrent for dogs and bears. Uses for individual products containing capsaicin vary widely.
It is applied to foliage of plants to deter feeding by insects such as spider mites, lace bugs, and other invertebrates. Capsaicin is used as an insecticide in addition to its use as a repellent.
Capsaicin is toxic to some bacteria and has been evaluated for use as a marine antifoulant.
Inhalation results in inflammation of pulmonary tissue and damage to respiratory cells. Capsaicin also irritates skin, sometimes severely.
In insects, capsaicin’s toxicity appears to be through metabolic disruption, membrane damage, and nervous system dysfunction. Capsaicin has also been shown to repel insects as well as kill them.
Capsaicin triggers the release of the neuropeptide P from the sensory nerve fibers of the C type. In mammals, capsaicin binds to the TRPV1 vanilloid receptor. The TRPV1 receptor then releases sensory neuropeptides that trigger a neurogenic inflammatory response.
NON-TARGET ORGANISMS:
Modes of toxicity for non-target organisms are expected to be similar to those of targeted insects and mammals. Capsaicin is considered toxic to honeybees and other beneficial insects. Although birds have the TRPV1 receptor, it is not activated by capsaicin. No information was available regarding toxicity of capsaicin to fish or other aquatic life.
DERMAL:
Capsaicin can cause skin irritation. Little absorption occurs across the skin. Edema following dermal exposure in mouse ears in several studies peaked within 1 hour of application, although subsequent applications produced less of a response.
Capsaicin can severely irritate the eyes, and was found to cause corneal lesions in rats and mice.
The dermal LD50 was determined to be >512 mg/kg in mice, however no signs of toxicity were noted at the doses tested.
Capsaicin produces its repellent effect when it contacts either eye or respiratory tract mucus membranes. Signs of acute exposure include coughing, inability to vocalize, and temporary blindness.
Mice and rats dosed orally with 96 to 200 mg/kg capsaicin demonstrated immediate salivation, convulsions, reddening of the skin, and dypsnea, or labored breathing. Animals either died within 26 minutes of dosing, or showed no further symptoms 24 hours after dosing.
Inhalation exposure to capsaicinoids in pepper sprays damaged rat bronchial, tracheal, nasal, and alveolar cells, causing acute inflammation.”
Since capsaicin is toxic to some insect species and causes PAIN to mammals, I think it should be avoided. We should move away from the thinking that we should use such deterrents on “pest” species. I have decided that a little seed for squirrels and more for birds is a good compromise for me. Since squirrels do take more than their share, I alternate between cracked sunflower seeds and safflower seeds and millet seeds. We do have a resident chipmunk who will eat safflower seeds all day long with a big smile on his/her face, but chipmunks hibernate, and once he has taken his winter hoard, we don’t usually see him again until the spring. While there are safflower seeds in the feeder, I toss a few peanuts out on the lawn every day, and they are taken away within the hour.
Most squirrel-proof feeders offer a modicum of protection, however, squirrels can eventually outthink most mechanical deterrents! Some squirrels have figured out that they can just launch themselves at feeders protected by anti-squirrel baffles, bounce off and eat the resulting seeds that are spilled on the ground. For every problem presented to a squirrel, there is a solution!
“Solutions” that frighten, hurt, or shock squirrels are cruel, and may also hurt birds too. Please try kinder methods first.
heatherclemenceau 
I never even thought about this.
Thanks Healther.
My sister lives in the mountains and has a lot of trouble w/bears, coons and other assorted mammals. The bears hibernate, the squirrels are smaller than town squirrels and aren’t as destructive. Mostly it’s the bears. She just lives with it and buys new feeders every year. The bears love to tear down her feeders. She quit feeding the turkeys since they were coming up on her deck and knocking on the glass door, besides shitting everywhere. They have left. I don’t think she’s ever tried hot pepper.