Cats are natural carnivorous hunters, and many cats will kill birds given the opportunity. Bird lovers can take two main approaches to reducing cat predation. One is to try and exclude cats from the garden, and the second approach is to minimize the likelihood of success for a marauding cat. No one technique is likely to be effective on its own if the problem is neighbourhood cats, but combining several will reduce cat kills in a typical garden.
Steps for Cat Owners
In the US humane societies recommend keeping cats indoors, but in Europe common practice is to allow cats out and they will roam by nature. Bird predation usually peaks in the early years of a cat’s life, about three years old, but usually drops off as the cat gets older unless it is kept specifically to keep small mammals down.
Cat owners who want to reduce the number of bird kills may wish to take some of these steps:
Keep the Cat indoors - Recommended by the US Humane Society for the cat's own welfare.
Attach a Bell to a Collar for the Cat
Cats are intelligent and can learn to creep along so that the bell does not sound much, but this gives birds and other wildlife some warning of their approach. This does not prevent stealth attacks - no bird will be able to react to the sound in time, but it does alert feeding birds to an approaching cat.
Do Not Put the Cat Out at Night
If you own a cat and want to let it outside, get it to come in for a main meal in the evening and then not go out again till next morning. Dawn is a particularly dangerous time in the garden.
Keep Claws Trimmed in the Spring
This reduces the cat's ability to scale wooden fences at speed
Minimising Cat Strike Success
Cats are opportunistic stealth hunters. Birds are most vulnerable when feeding, and particularly when feeding on the ground. Site feeders away from low-level ground cover that can hide waiting cats. The problems with feeders is not so much the birds on the feeders, but the ground-feeding birds that forage under the feeders for dropped seed. If there is existing ground cover that cats pounce from, a low fence in front of this can be decorative and thwart such attacks. Feeders should, however, be within a couple of metres of shrubs at feeder height to give feeding birds some chance to get cover from aerial predators such as sparrowhawks.
Cats can easily scale wooden poles such as those used to support bird tables. Slide a length of plastic drainpipe over the pole to stop this – the cat’s claws cannot dig into the surface so climbing the pole is much harder.
Excluding/Deterring Cats
It is hard to exclude cats from a garden 100% of the time, but they can be made unwelcome.
Fences
A good perimeter fence is effective as long as cats cannot climb it. Cats can easily scale wooden fences with their claws, which is why the Cats Protection League recommends a close-boarded wooden fence with a parallel planted hedge to keep cats out. If there is already a wooden fence a wire run about 2cm above it makes it harder for cats to stay on top of it. Chain-link fences higher than 1.5m are cat-proof, but rather ugly. Cats can scale the posts - keep posts on the bird side of the fence. Spiky plants like holly also deter cats.
Ultrasonic Deterrents
These are set off by the cat in the same way as security lights, and emit a high level high-frequency noise. Success depends on the particular cat – some seem unfazed by the noise, but the RSPB in a study determined that the Catwatch type reduced cat-hours in a garden by 50%
Water Deterrents
These range from the time-honoured bucket of water, to a Super Soaker water pistol to powered devices connected to the garden hose which detects the cat's body heat and sprays it with water. These are effective but either expensive or time-consuming, though satisfying!
Smell Deterrents
The downside of all smell deterrents is that they last only a few days so they need frequent renewal.
Cats do not like citrus smells, so citronella sprays can be used, or even orange peel. Clay balls saturated with pepper/mustard smells are available, though the smell is noticeable to humans and not particularly nice.
Lion dung is sold to deter cats, but users seem to experience mixed success.
A plant has been bred, called Coleus canina, which exudes an unpleasant smell that most cats loathe. It will not tolerate a frost, unfortunately.
Finding neighbouring cats killing the odd bird takes away much of the pleasure of bird feeding. No one action will eliminate cat kills, but intelligent feeder siting can reduce the chances of successful stealth attacks. Use this together with exclusion and deterrence methods and the number of birds lost to neighbourhood cats will be greatly reduced. Cat owners can help by not putting their animals out at night, and fitting bells to their cat's collar.
References
The Royal Society for the Protection of Birds (RSPB) on cats
The Cats' Protection League on reducing cat straying
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