Rats in Your Garden and Compost Pile. What You Can Do About It.
Here’s some helpful advice on how to deal with rats in your garden and compost pile before reaching for a trap or that box of rat poison.
Rats Love Garbage
Not only can composting your garbage provide you with a great source of broken-down organic matter to feed your garden, but it can also provide a smorgasbord of feeding opportunity for rats. And unfortunately, you may not notice that you have a developing rat control problem until the rats have literally taken over their new-found favorite habitat—your garden and/or compost pile.
The following is a summary of an hour-long webinar presentation by Dr. Dana Sanchez (Oregon State University Extension Wildlife Specialist) for a special session on managing rats in yards, gardens, and compost piles.
Know Your Enemy
One of the key things to understand when it comes to rat control, is to know your enemy—where he lives, what he likes to eat, his preferences for a home, how he gets around, and his habits or idiosyncrasies.
Rats in your garden or compost typically will be of one type or the other—Rattus rattus (also known as the black rat or house rat or ship rat) and Rattus norvegicus (known as the Norway rat).
Rattus rattus is great climber able to scale up gutter pipes to enter into the attic of homes. Sometimes, when a structure is not easily available, they can and will burrow into ground. The Rattus rattus tail is usually longer than body plus head; has large nearly hairless ears; possesses a narrow-pointed muzzle; has an average total length of 14 inches; weighs between 2.5 to 10.5 ounces, and has a territory range of 125 square yards that it will aggressively defend. A lesser known fact is that this species can drop off its tail when evading a predator.
Rattus norvegicus is typically larger, weighing 5-18 ounces with a total length of 14-17.5 inches. This species prefers to make ground level nests and burrows; has a range covering up to ½ an acre; and is more fecund producing up to 7 litters per year at 9-10 pups with each litter.
Rats Are Destructive Disease Carriers
While some may be tempted to believe that as long as the rat stays to the compost pile that it’s ok to let nature live, it’s actually a bad idea. Rats will not stay put and rats will reproduce like…well, rats.
Rats will do damage to your property surrounding your garden and compost, that includes your ornamentals, shed, landscaping, garden crops, birdfeeder, and home. It’s just a matter of time. In addition, rats carry and spread up to 35 different diseases. However, as an aside it bears mentioning at this point that the Hantavirus is not due to rats or the common house mouse, but with the tiny white bellied deer mouse.
What Rats Look For
While food is a primary attractant to rodents, rats look at a potential habitat with a critical eye towards survival and reproduction, taking into account factors such as resource availability, quality, accessibility and safety with respect to predators near a potential habitat.
For centuries rats have lived in close community with humans. They are curious creatures that are attracted to new construction and teardowns and will explore such disturbed areas in search of new opportunities and a new home. Being both nocturnal and crepuscular, rats are very capable of evading detection outdoors. However, it is knowledge of their very habits that gives us a one-up on how to control them.
Basic Rat Tactics
Avoiding the Problem—the first step is to avoid attracting rats. You can this around your home and garden by:
• Removing lumber and junk that attracts insects which rats may feed on.
• Storing garbage in tightly sealed garbage cans.
• Controlling grubs in the lawn.
• Removing birdseed spillage from feeders.
• Never leaving food out for animals such as squirrels and raccoons.
• Never leaving pet leftovers in food bowls outside.
• Removing downed fruit from around plants and trees.
• Manipulating their potential habitat to raise the danger of detection.
Modify their habitat to reduce their carrying capacity (how many animals can be fed and supported in that area)—You can accomplish this by understanding that rats have routes they prefer and will use regularly. Rats prefer narrow pathways, fence ways and power lines for getting from point A to point B, which provides cover or distance from harm. Open spaces are avoided by rats because it makes them visible to predators.
You can also modify their habitat by blocking their access to the garden or compost pile with welded wire/construction cloth; or, by installing a metal skirt to surround the area. Chicken wire is too weak to withstand a gnawing rat.
Enclosed compost tumblers are the preferred way to prevent rat problems. However, good management as described above will significantly decrease your chances of having rats in spite of having a typical open compost pile or box. Adding construction hardware cloth below the compost and putting rat-proof fencing around the pile and on top will also help when using non-tumbler type composters.
Removing rats is not easy
• Few—if any—commercial scent products demonstrate any replicated tests of being positively effective in driving rats away.
• Rats are neo-phobic—they fear anything new and will often avoid new trap and bait boxes.
• Rats have an effective source memory that reminds them of the last time they tasted a particular poison or bait and that it made them sick. As such, they will remember a past poison and will actively avoid it and thereby become bait-resistant.
• Rats are fast, agile and typically avoid the high activity hours of humans and pets like dogs.
• Cats are not good rat killers, they rarely go after a rat. Cats prefer smaller defenseless prey. Cats kill far more other species such as birds. Terrier packs, however, are very effective for larger farm area, vineyards and infested downtown areas for hunting and killing off rats.
Maximizing Your Trapping Effectiveness
• Snap traps offer a quick humane death—be sure to use rat size, not mouse size. For indoors you can consider electronic traps that can electrocute the rats.
• Wear gloves—rats know to associate human scent with danger. They consider humans to be among their predators.
• Teach rats that traps are not a big deal by leaving them out with bait, but without the trigger set. You want to reduce their neo-phobia and lull them into a false sense of security.
• Place the trigger to the trap in a travel path along walls, runways, and with the traps edges at a 90-degree angle to the wall. Sometimes even without bait, rats will run right into the trap.
• Good bait: smelly cheese and peanut butter are most effective.
• Use lots of traps.
• If you use poison, you must read the label and follow the directions exactly. The label is the law! Improper treatment of voles for example with poison kills thousands of geese every year. Using too little that is sub-lethal can result in cats, dogs, foxes, and predatory birds becoming poisoned by a weakened, but still alive rat filled with poison.
If You Need to Farm-Out the Rat Control
If you find that your rat problem is out of control, you have two options (besides selling your home): a pay-for commercial pest control company; and, in some states, a Wildlife Control Office (WCO) from the state Fish and Game department whose rat control help may come free of charge.
Here’s a YouTube Video of the Entire Webinar for more details:
If you have ever had a rat problem with your compost, please let us in know in the comments section below how you dealt with the problem.
Timothy Boyer has a Ph.D. in Molecular and Cellular Biology from the University of Arizona. For 20+ years he has been employed as a freelance health and science writer. Today, with a background in farming and an avid home gardener, Timothy continues writing about science with a focus on the connection between plant biology and gardening for healthy living. For continual updates about plants and health, you can also follow Timothy on Twitter at TimBoyerWrites.
Image courtesy of Pixabay
Reference: “Oh Rats! Dealing with Non-native Rodents in the Garden” Oregon State University Extension Service’s 2020 series of Advanced Training Webinars for Master Gardeners.