Deer have 297 million olfactory nose receptors. When odiferous air molecules enter the nose, these nerve cells transmit messages to the brain. These same receptors trigger the instinct to blow and run when the human scent is detected. Deer instinctively blow to clear the triggering scent from the nose and to alert other herd members of danger.
I have used this natural instinct against them for two decades to keep them from eating my fruit trees, berry bushes, and decorative landscaping by simply being offensive. Deer won't eat around anything that triggers brain sensitivity. Humans and deer both have nuclei in the brain called the amygdala. This area controls emotion, learning, memory, and food intake. There are a few scents that activate a deer's amygdala in the brain, telling the deer that the area isn't safe for consuming food.
Synthetic scents and products don't tend to work well because most generations of deer have not been exposed to these synthetic smells. Without exposure to a product, they often haven't learned a negative response and are not triggered into avoiding food in the area. Bloodmeal isn't wholly effective because does that give birth often consume the placenta for the extra nutrients needed to produce milk, and often return to the birthing area for safety where there is old blood residue. Bone meal has been heated and treated. This also removes most of the odor. Commercial sprays that contain egg albumen (egg whites) also don't work 100%. The spray isn't designed to repel the deer by scent but instead by taste. Protein (egg whites) on plant leaves will detour herbivores but only after a few chews. If you have six deer passing by, you will still lose a lot of foliage.
Scents that deer find neurologically offensive are manure, offal (not blood), and fish oil. In nature, all of these scents have been around deer since the dawn of time. Instinctively deer will not eat food around manure or dead animals or drink stagnant water. A human can smell manure, dead animals, and the fishy odor in stagnant water with only 400 olfactory receptors. Imagine how offensive these odors are to deer that are multiplied 742,500 times compared to our own olfactory senses! If you think manure stinks, it stinks to high heaven to them! This is also why deer don't graze in the same pastures as cows unless they are starving and are highly overpopulated.
Using fresh manure, offal, or fish oil will repel deer, and it is easy to do on a large scale. This photo is of a regular November evening during the hunting season. These does will all give birth around May. Many will have twins. Here is how I do it to keep the healthy herd of deer, on our 178 acres of timber and food plots, off my fruit trees, grapevines, berry bushes, weeping willow saplings, decorative landscaping including massive hostas, and out of my organic garden.
Cut old fabric into strips about two inches wide and two feet long. Cotton fabric works best as nylon, polyester, and spandex are plastics that don't tend to hold scent as well but they will do if that is all you have.
Make sure there is no rain in the forecast for 24 hours. In a large bucket, collect uncomposted, mostly fresh manure. Store-bought bag manure will not work as it is composted and often heated to remove potential pathogens, which changes the scent to be dissipated and earthy, ultimately reducing its effectiveness as a repellant. Add enough water to the fresh manure, make a thick manure tea and stir with a good ol' stick until most of the manure clumps break up.
Take the bucket of manure tea and the fabric strips to your fruit trees. Using latex gloves, dip a fabric strip into the manure tea. Do not add all strips of fabric at once because they tie in knots, and you will flip manure tea all over yourself trying to untie them; That was an unpleasant rookie mistake. Swish a single strip around to get it as dirty as possible and tie it onto a lower outstretched limb that will not dangle or blow onto fresh growing fruit. Large trees may need six to nine fabric strips to repel deer that come to graze upwind. Small saplings only need one strip near the center of the tree. If manure strips around your fruit seem unappetizing, don't forget songbirds visit fruit trees daily and also leave fertilizer donations.
For shrubbery, flowers, or flower beds, I dress the mulched area with hot uncomposted manure in a circle around the base of each plant about a half-inch thick and at least four inches wide, careful not to touch the stems. Hot manure will burn the stem of the plant it touches. My livestock manure often contains hay, grass, or oat middlings so I mulch up to two inches thick and it remains fairly invisible to the eye on woodchip bedding. Rabbit manure will not harm a plant if it touches the stem as it is not considered hot. The benefit here is that the manure also fertilizes the plant so it grows quickly and is healthy which also repels bugs.
Please note that pH-sensitive plants such as hydrangeas and mums can change to rusty red colors from adding manure.
If spreading that much manure by hand isn't your jam or you can't get manure, you can put cod liver oil or any cheap fish oil in a pump sprayer to use around the base of plants, careful not to get the oil on the plants as it will burn. You can use it in liquid or pill form as long as it isn't labeled as odorless. Dump the entire bottle of cod liver oil into a bucket and add a little water, enough to wet your fabric strips. It may take 20 minutes for pills to dissolve. Again dip and tie the smelly strips in your fruit trees or in tall berry bushes. It is also safe to mist the trunk of the tree with well-watered-down oil. The sprayer must also be shaken up to mix the water with the oil since they do not blend. You may have to use a kitchen sieve to remove the gelatin capsules if you are not patient enough for them to completely dissolve.
Cod liver oil may bring in cats, raccoons, skunks, and possums that disturb your garden areas looking for vittles. Manure works best as cats like to have a private bathroom area that isn't used by other animals. Manure also works for chipmunks, ground squirrels, and regular tree squirrels that sometimes take vines to build nests.
Alternatively, if you are a homesteader or are processing animals at home you can use offal such as intestines, gizzard linings, hide or skin strips, even chicken feet in trees or bushes that do not produce food for humans. I use chicken feet for broth, see that blog here, but I use chicken intestines on our weeping willow saplings and around the trunks of fruit trees to keep the deer from eating the saught after spring foliage and to keep bucks from rubbing the bark or lower branches off of the trees in fall. After a few weeks, the offal dries to a crisp but is still functional as deer repellant. Occasionally, a hungry critter may remove them, but for the most part, they remain through the winter months until processing time again.
Using manure or fish emulsion in your garden will also repel deer. Back before I had poultry netting for garden fence, I would easily repel deer that would come in to eat the tops off of my sweet potatoes and dig to eat the tubers by side-dressing the potato hills with fresh chicken litter. If you don't want to use those products in contact with the soil you can tie the soaked fabric strips on your fence or tie them to garden stakes in surrounding areas.
After a few years of doing this, deer avoid the area as they no longer want to waste time looking for food in an unrewarding area. I have taken a year off from time to time without them returning. Now if we can just repel those pesky birds. I have a blog for that too coming soon!
I have been homesteading for two decades, growing and processing all of our food. We live independently off the food chain. It took me five years to write a story-based novel about my journey to living off the land. You can find this empowering book on Amazon in Kindle and Paperback HERE.
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