Staff August 9, 2016
Humane Critter Control
Photo: iStock unless otherwise noted.
Your clients spent a bundle on the best plants available, only to find out that they’re favored by local wildlife. But your clients also have very soft hearts when it comes to the cute critters who are making a meal out of their precious plants. How do you protect the plants while sparing the wildlife?
There are many humane options for preventing damage to valuable landscape plants, ranging from natural pheromones to physical barriers, but sometimes the most effective means of prevention is specific to the type of critter that’s causing the problem. The scariest scarecrow might prevent crows from depleting your clients’ small plot of artisanal corn, but it won’t mean a thing to that vole who’s wreaking havoc on the lawn.
Here’s a look at three of the most common — and vexing — animal pests, and what can be done to prevent devastating damage.
Rabbits love to chew the tender new foliage of perennials as well as, oh, whatever else is available.
Rabbits
Rabbits prefer to feed on the succulent foliage of grasses and herbaceous perennials, but they’re known to gnaw on the tender bark of young woody plants, too. Vegetables? They’re a given. (They also tend to breed like, well, rabbits, so if you see one culprit in the garden, you’ll likely see more.) What can be just as frustrating, however, is that they can cause extensive damage to irrigation lines by chewing through the plastic, especially if the system employs smaller diameter tubes.
How do you know if a rabbit is the outlaw causing devastation in the garden? Most damage will be found close to the ground, unless snow cover or natural ladders are available to help them reach higher. Even standing their hind legs, as they will occasionally do to reach munchies above their own height, the damage is usually limited to about one foot (or slightly higher) from the ground.
The more distinctive sign of rabbit feeding is the angle of the cut; sharp incisors allow them to make a characteristic 45-degree slice when they’re chewing off flower heads, buds or woody twigs. This damage is in contrast to that caused by browsing deer, who must twist and pull twigs and shoots on woody plants, leaving a ragged mess. (At least we can say that rabbits are neat.)
What to do?
Although many states consider rabbits to be game, your clients would just as soon not shoot anything but their budgets. So the three primary means of protection from rabbit damage are exclusion, trapping and repellents.
If the landscape permits, exclusionary netting or fencing can keep rabbits at bay. Chicken wire with a mesh size no larger than 1 inch (baby bunnies are small) can be mounted to light stakes or posts. The wirework should be a good 48 inches tall (rabbits can jump!), and the bottom should be buried at least 6 inches into the ground (rabbits can dig); 10 to 12 inches is better. This will prevent rabbits from burrowing under the fence to reach those tasty treats.
When we say, “if the landscape permits,” we’re thinking about aesthetics. Dark colored wire may blend with foliage, but remember that rabbits chew through plastic, so plastic netting won’t do.
Similar fencing may be required for use as trunk guards, protecting the tender bark of young saplings.
Live trapping may be a tricky solution. Why? Once trapped, the rabbit must be relocated. Many municipalities don’t allow transport and relocation of trapped wildlife, unless performed by a licensed agent. However, if trapping is allowed, the rabbit should be relocated a good five miles away, preferably in a wildland area, of course. And remember what we said about rabbits breeding like rabbits? Be prepared to set several traps and make several trips.
If the trapping solution is selected, it’s critical that the cages be inspected daily, if not several times a day. Are you willing to take on that task? Is your client?
Chemical repellents work by creating an odor or taste that is abhorrent to the pest. Repellents can be effective, but they should be applied before damage occurs and must be reapplied frequently. How often? It depends on the type of repellent (and what the label recommends), but in general reapplication should be made following rain or sprinkler irrigation, after a heavy dew, or when new growth emerges.
This prevention method is limited in effectiveness on many types of rabbit- friendly plants, however, because most of them should not be used on or near edibles. They’re most effective on trees, shrubs and vines.
Habitat management also can work; many rabbits prefer to snuggle cozily beneath cover of low-growing shrubs, within tall grasses or under nearby structures, coming out only to romp and feed. If such hideaways are eliminated, the critters likely will hop along to a safer garden. But some gardens happily feature low-growing plants and ornamental grasses, which clients would prefer to keep. Tidying up helps.
Although not necessarily the worst offenders, squirrels may steal fruit and nuts or nibble on some plants.
Squirrels
If your projects include areas for edible plants, make sure the homeowners understand that squirrels, those adorable, acrobatic little rascals, will nibble just about anything humans want to harvest. So it’s often recommended that diversionary tactics be employed. Distract them; offer them their own feeder, complete with nuts or cracked corn, the thinking goes, and they’ll be so happy they won’t bother the garden plants.
However, these industrious little beasts also cause indirect damage to plants by digging and burying their treasures. This can create a mess in the neatly laid mulch; worse, their digging can disrupt roots. Plus, if the seed they cache is capable of sprouting, the homeowner may be surprised to find lush stalks of corn sprouting among the Coreopsis. (Corn often can be found sprouting in gutters, too, but that’s a problem for the homeowner’s handyman.)
On the other hand, when they’re not digging to bury future meals, they’re digging to find tasty bulbs; squirrels love tulip and crocus bulbs and can sniff them out wherever they’re planted. Daffodils? Not so much.
Fruits and nuts growing on trees offer a veritable banquet for squirrels, and it doesn’t matter whether the apples, for example, are produced on ornamental crabs or orchard trees. They’ll also chew the tender buds of trees, which, if the pests are ravenous enough, can result in slight defoliation.
Lawns also suffer from squirrel damage, although it’s merely aesthetic. These rodents will bury their winter food supply wherever they can, and often that’s in the middle of the lawn. Small holes, usually about the size of a U.S. quarter, may dot the yard come fall, when the drop in temperature triggers their caching instinct. Turf will recover nicely without intervention.
Robust corn stalks growing among sedum are a sure sign of squirrel activity.
Photo: Sally Benson
What to do?
As with rabbits, exclusion may be the best option for protecting precious plants from squirrel damage. If your garden design includes small flowering trees and shrubs that produce fruit, netting the entire plant for a period may help to preserve the crop. Because squirrels are capable of climbing just about anything, a small cage barrier at the base of the trunk will only give them more equipment for their gymnastics.
Fruit trees also can be protected by wrapping the trunk with a band of sheet metal, located about 6 feet above the ground. The band should be about 1-1/2 to 2 feet wide. This slippery surface will present the little climbers with too great a challenge to reach the buds and fruit in the tree’s crown. Bands should not be left on permanently, and they may work only if surrounding trees are also banded, or if trees are not sited close enough for squirrels to jump from the branches of one tree to the next.
Just as with rabbits, if your client prefers trapping to manage the squirrel pests, be sure to check the local and state laws regarding their handling. Trapping squirrels has become a profit center for many private wildlife management companies; the little devils love to make their way into attics to nest. Hiring such a company is an option, and it transfers responsibility to another party, allowing you to do what you’d rather be doing.
The application of repellents can be an effective way to deter squirrels, and those containing capsaicin are especially popular. Oil of mustard, peppermint oil and vinegar also can be employed, with varying results. Remember that repellents require vigilance and repeated application.
On the other hand, commercial ultrasonic devices can effectively annoy the heck out of small critters, sending them packing to the neighbor’s crop. The frequency emitted is inaudible to humans, so it won’t bother the homeowners (or their neighbors), and it’s also inaudible to dogs and cats. These devices may take a while to be effective, up to 2 weeks in some cases, but aside from requiring an electrical cord running through the garden, it’s harmless to all but the pests.
Motion-activated sprinklers, often recommended for squirrel management, can scare away unwanted critters by briefly squirting a sharp stream of water toward whatever living being enters its perceived territory. Thus, it also squirts welcome critters, including the family dog. Or party guests.
As for the old trick of hanging scratched CDs in trees? Who has CDs?
Much of the damage caused by voles can be seen in the extensive network of tunnels they create throughout lawn areas.
Voles (and similar rodents)
Tiny voles come in a variety of species and appetites, but the common vole is a primary pest of that lovely carpeted lawn. They’re active 24/7, and because much of their activity is underground, you may not know they’re around until you see the damage. Their tunneling behavior is legendary; these miniature creatures create a vast network of tunnels and burrows where they nest, breed and store the fruits of their foraging efforts. Intertwining highways of vole damage can be seen in otherwise healthy lawns.
Their urban planning efforts aside, voles (and other tiny beasts) can cause extensive damage to a variety of ornamental plants, feeding on grasses, perennials, bulbs and tubers, and seeds. They love their vegetables. They dig in containers. They gnaw on shoots and leaves.
The bark of small trees and shrubs also feeds voles, who are poor climbers but can cause lethal damage by chewing enough bark to girdle trunks. Even in winter they’ll snuggle under snow cover, if they’re lucky to find such, and nibble on whatever’s available, — most likely the bark of small trees and shrubs. Damage may be evident from a few inches aboveground to a few inches below ground, and even though their tiny legs are not built for scaling trunks, they can climb onto low branches and eat their way ever higher.
He’s adorable, yes, but he ate my tree.
What to do?
Habitat modification and exclusion may be the most effective ways of preventing extensive vole damage. They love to take up residence underground, of course, but they’re also partial to settling in among weeds, heavy mulch layers and dense vegetation. Cleaning up the area helps. For trees in particular, provide a 4-foot-diameter around the base that is free of vegetation; voles don’t like exposure, and if there’s no place to hide, they’ll go elsewhere.
Wire fencing with a mesh size of ¼ inch or smaller — yes, that’s tiny, but so are the voles — will help to exclude them from protected areas. Fencing should reach about 12 inches aboveground and should be buried 6 to 10 inches belowground. (Remember, these guys are expert tunnelers.)
Photo: Sally Benson
Tender trunks can be protected with tubes of heavy plastic, sheet metal or hardware cloth, but be sure that there’s sufficient room for the trunk to grow. The cylinders should be buried slightly, and in areas where snow cover is likely, they should be tall enough to extend above the snow level. Such sleeves should be monitored closely to be sure voles haven’t been able to sneak past the barrier and high inside the guard.
Live trapping and relocation isn’t often recommended, primarily because of the large population and the number of traps required to make a difference. (Voles are prolific, with females capable of having five to 10 litters of 3 to 6 pups per year.) That, and their network of tunnels makes it quite the challenge to capture.
The use of repellents is, unfortunately, not often successful. Although commercial repellents are available, their use is often simply not practical.
So we turn to natural control. With the exurbs and the suburbs increasingly encroaching on wild lands, predators are no longer uncommon. Foxes and coyotes, both of which feed on small rodents, may help to control the population. Owls and hawks also eat voles. None of these will eliminate the problem completely, but they may remove enough to create a more acceptable balance.
Small mammalian plant pests can be managed humanely, although it takes ingenuity and patience. Lacking that, employ the homeowner’s dog or cat.
Read more: Managing Rabbits, Rodents and Slugs