4/5 – a sustainable approach with potential for public concern

Creating seasonal employment for hunters, associated jobs in the food industry, and reducing our dependence on fossil fuel-intensive livestock production, wild meat has a lot of potential. Our deer population is unnaturally high, with no large carnivores to control their numbers – and introducing big predators to our farming communities is not a feasible solution.

So, hunting is an important part of a rewilding approach to controlling deer populations, without putting up barriers to animal movement. A vegetarian myself, I’m still happy with the idea of eating an animal that has led a wild life, with a natural diet, free to roam the countryside. Harvesting deer at sustainable levels is also a way to make conservation pay for itself.

4/5 – protects early growth but alternatives to plastic aren’t as good.

These are such a standard feature of our landscape that you might not even notice them anymore, but there’s a lot of variety when it comes to these tubes that enclose a growing tree. The shape can influence the way that a tree grows out and newer guards are being researched which can biodegrade. However, the likelihood is that you’ll be using plastic, as the new versions are still in a testing phase (Woodland Trust).

Obviously, with it being plastic, there are environmental impacts, includes shedding microplastics into local water systems. However, tree guards are a proven way of reducing deer damage to trees in their first few years of life. They will need removing and recycling when the tree gets bigger, after which it will again be vulnerable to deer damage.

3/5 – prevents individual tree damage in parkland long term, but costly

Small enclosures made from wooden stakes and wire mesh bridge the gap between a fence and a fence alternative, but they are a well-established solution for protecting isolated trees from deer damage in the long term.

A more attractive version of these are the ornate black ironwork cylinders that you find in some parks, commonly described as ‘parkland tree guards’. In woodland, these are more expensive per tree than fencing the perimeter of a site and they make the landscape look less natural.

3/5 – effective long term with constant patrols across an area

Perhaps this might seem obvious to you if you already own a dog, but dogs can be used to scare deer away from an area. This is a higher effort method unless you’re protecting an area already connected to a house, but a 1994 study found that dogs were an efficient way to protect a tree plantation. A 2021 study used dog barking alongside deer alarm calls to scare deer away from an area, and a 2008 study found that they can be used to prevent deer from stealing cattle feed.

As with most other items in this list, the effect decreases with distance, so regular patrols or a free-ranging animal is necessary to keep deer away.

2/5 – effective for a few weeks only in small areas

While the deterrents you can buy online tend to be ultrasound emitters, the sounds used in scientific studies seem to be mainly deer alarm calls. A 2004 study found that regular use of a deer alarm call is not effective, as deer quickly get used to the sound, even when it’s only triggered by their movement with IR detectors.

The standard garden IR detectors which play a deer-scaring tone were tested in a well-designed 2019 study. While there was a significant reduction in deer passing through a small boundary gap at first, this effect, like with the alarm calls, wore off over time.

2/5 – very effective only when applied regularly to all foliage

There are a variety of deer repellent sprays on the market, including one spray, Big Game Repellent, which has featured in several peer-reviewed studies, though effectiveness ranged from 100% to 0% effectiveness depending on the conditions! The same manufacturer sells Deer Off Weatherproof Deer Repellent in the UK market, though reviews of the product are mixed.

A component in baby milk, hydrolysed casein, is a cheaper way of deterring deer when sprayed onto plants in a 12% concentration with water. A 2006 study found it to be extremely effective at deterring deer and cheap to make, but every branch had to be coated with the substance, and it left a ‘white or cream coloured’ residue on vegetation.

For any deer repellent to be effective, scientists say it must be applied directly to branches, and reapplied regularly. This makes any repellent a time-intensive and potentially costly solution.

2/5 – moderate effect, needs applying to every plant

The smell of certain soaps seems to deter deer when they’re present at low densities. This is backed up by a 1990 study in the US, though the effect was only a 40% reduction in damage within 1m of Ivory Soap. People who still use this method recommend cutting up Irish Spring soap and sprinkling it around any plants or trees you wish to protect. This will need to be topped up frequently to keep it fresh.

SFGate suggest a different method, hanging soap from trees 2m off the ground, within 1m of the plant or tree you wish to protect.

While there is scientific evidence for this solution, it’s going to be hard to do at large scales, becoming time consuming. Every tree needs its own soap repellent, so this is not a boundary system.

2/5 – moderate effect, needs applying to every plant

Hanging balls of human hair around your trees might not sound like a particularly sane thing to do, but there is data showing that it can reduce deer damage. The balls are 10-15cm wide and hang about 1m or less from the ground on the trees you want to protect. A 1987 study found that this reduced deer damage by about 30% – whether that’s enough to justify being ‘that person who has human hair balls hanging from their trees’? Well, that’s up to you!

A less creepy method of using human hair which is reported to work on internet forums involves spreading it around the base of plants. Hair is biodegradable, but be aware that it may contain harmful chemicals from hair or cleaning products if it’s sourced from a hairdressers’ shop.

1/5 – weak effect requiring regular retreatment

Some people suggest that you get the male members of your family to urinate around your property. However, the evidence for human urine (or even faeces – yes, really) is anecdotal, and many landowners say that deer get used to it over time.

Another suggested solution is buying predator urine or the chemicals found within it. A 2014 study tested how effective pyrazine (a component of wolf urine) was to deter Hokkaido deer feeding behaviour. However, the trial was very unnatural, covering a sheet in the deterrent chemical, on which the food was placed. Even then, some deer continued to browse on this food, though the numbers were lower than the sheet without pyrazine.

So, although wolf urine and other predator urine products are available online, they are unlikely to be very effective.

0/5 – dangerous and ineffective

Some people use sharpened stakes driven into the ground at an angle or behind low fences to prevent deers coming onto their property. As one commenter points out, removing a half-dead, skewered animal from a stake isn’t pleasant for you or the animal. This method is also dangerous for any humans in the area and could land easily land you in court for recklessly endangering the public.