New York State IPM Program

November 22, 2017
by Joellen Lampman
Comments Off on Gray squirrels skittering around to keep up — their pantry or yours?

Gray squirrels skittering around to keep up — their pantry or yours?

PUBLISHED ON November 11, 2017 | Courtesy Paul Hetzler, CCE St. Lawrence County

“Squirrels have been criticized for hiding nuts in various places for future use and then forgetting the places. Well, squirrels do not bother with minor details like that. They have other things on their mind, such as hiding more nuts where they can’t find them.”

Although those that feed birds think squirrels are there strictly to torment them, squirrels are quite useful in maintaining hardwood forests.

Unfortunately, that succulent passage was penned in 1949 by W. Cuppy in his book “How To Attract A Wombat.” I say unfortunately because I wanted to write it first, but was unable to get born in time. The tradeoff, which is that I got to be quite a bit younger than he, probably worked out for the best anyway.

Before learning stuff like “facts” about squirrels, it made me feel smug to think that their attention span was even worse than mine. Popular wisdom used to hold that the fluffy-tailed rodents spent half their lives burying nuts, only to forget about most of them a few minutes later. I figured that was why they generally seemed frantic, always thinking they hadn’t stored any food yet.

The great thing about the whole affair is that tons of butternuts, oaks, hickories and walnuts get planted each fall, mostly in flower boxes, but some in actual forests where they can grow to maturity. As a kid I would see untold numbers of squirrels in parks, on college campuses and around dumpsters, but few in the woods. The latter, I assumed, were lost, or in transit to a day-old bakery outlet.

So it came as a surprise to learn gray squirrels are native to temperate hardwood forests, at home in large unbroken tracts of woods. In fact, squirrels are critical to the survival of many nut-bearing trees. Walnuts, acorns and hickory nuts, which do not tend to waft on the breeze so well, and which soon dry out and degrade on the ground, need someone to cart them off and plant them in the ground.

Gray squirrels can be so numerous in the human domain that they become pests. Photo credit: get down flickr

The irony is that while gray squirrels can be so numerous in the human domain that they become pests, they are disappearing from the forests that depend on them for regeneration. The reason is that most woodlands today are patchwork. In a shocking failure of the free market, it seems no one is making large contiguous tracts of forested land any more, even though they’re increasingly rare.

It’s hard to criticize agriculture, especially if you eat on a regular basis, but clearing land to grow food has fragmented our woods. One problem with breaking up forest land is that animals may need more than just a piece of it at a time.

Gray squirrels have large, shared territories with no real borders. Although they are great at things like tree planting and eating the faces off Halloween pumpkins, they’re not so good at running across fields to the next patch of trees. Well the running works OK, but not the looking out for predators. Gray squirrels evolved in a world where hiding places grew on trees. As a result, predation was low. But since the time they have been forced to hike out in the open, hawks, coyotes and foxes have taken a bite out of wild squirrel populations.

Red squirrels, however, are moving into habitats once occupied by gray squirrels. It seems logical to think that an army of red, fluffy nut-planters would be just as good as propagating an oak-hickory forest as the gray, fluffy sort were. Not so. The reds, which evolved among conifers, are accustomed to stashing pine, spruce and fir cones in hollow trees or right out in the open. When they encountered acorns and nuts, they carried on with this tradition. In the open-air caches of the red squirrels, tree nuts desiccate and become non-viable. Nothing gets planted. Also, red squirrels have smaller, discrete territories they do not share, so they’re not as apt as the grays to gallivant over to a nearby block of trees, and thus they avoid those pesky carnivores. In this way they’re better adapted to a fragmented forest than the grays are.

Getting back to forgetfulness, science has polished up the reputation of gray squirrels by observing them. Evidently no one thought of doing this novel procedure until 1990. That’s when Lucia F. Jacobs and Emily R. Lyman of Princeton University’s Biology Department set up a series of nut-caching experiments with gray squirrels. And hopefully a few interns as well. Their impressive article was published in the Journal of Animal Behavior in 1991, and is readily available online in case anyone has an attention span longer than mine.

I should mention that gray squirrels are considered “scatter hoarders,” stashing nuts and acorns all over the place. They tend to dig them up and rebury them as many as five times prior to winter, possibly to confound greedy neighbors or pilfering jays. Each successive re-cache takes them farther and farther from the parent tree, which is good in terms of forest ecology.

Jacob and Lyons concluded that even after waiting 12 days, gray squirrels quickly located about 2/3 of the nuts they buried, but that they also exhumed a few that weren’t theirs. However, each squirrel managed to end with at least 90% of the original number provided by researchers. This shows that memory is the primary means of locating cached tree nuts. And that while they don’t plant as many trees as we once thought, they make up for it by planting each one many times.

The search continues for a squirrel-proof bird feeder. Photo credit: Ken flickr

Many thanks to Paul for letting us share his piece! For more information on what to do to prevent squirrels from planting trees in your flower boxes or, worse yet, nesting in your attic, visit the New York State Integrated Pest Management Program’s What’s Bugging You – Wayward Wanderers webpage. When it comes to keeping them out of bird feeders, you are on your own.

Paul Hetzler is a forester and a horticulture and natural resources educator with Cornell Cooperative Extension of St. Lawrence County

March 17, 2015
by Joellen Lampman
Comments Off on The squirrels are coming, the squirrels are coming!!

The squirrels are coming, the squirrels are coming!!

“Spring work is going on with joyful enthusiasm.” ― John Muir

In other words, birthing season will soon be upon us. And though it’s fun watching animal families grow up in our backyards, it’s best that they don’t give birth within our buildings. Because female squirrels seek safe places to raise their young in late winter and early spring, now is the time to ensure they stay out of your attic.

Photo credit: Carosaurus

Give them an opening and squirrels will happily turn your attic into a nursery. Photo credit: Carosaurus

 

Your first step? Monitoring is key to sound IPM. In this case you want to inspect your building exterior, especially if you’ve had problems in the past. Since squirrels are climbing animals and there’s no way could you see all possible entry sites from the ground, you’ll need a ladder. If you find a likely entry hole, don’t close it without first determining if it’s active. Trapping an animal (or its nest) inside can provoke it to chew its way back out — or in. Monitor an opening by inserting a soft plug (crumpled newspaper works fine) into the hole. If the plug is still there after two days and you see no other signs of activity inside the building, it should be safe to permanently close the hole. What to close it with? Think galvanized sheet metal or galvanized metal mesh, which resist strong teeth.

Do you need to remove squirrels from the building? Trapping is the most common and successful method. By New York law, however, without a state-issued permit squirrels must be released on the property or humanely destroyed. Another method is to install one-way doors (also known as excluders) over entry holes. These devices allow animals to leave — but not re-enter — the structure. To be successful, one-way doors need to be combined with preventive exclusion (such as metal mesh and caulk) on other vulnerable sites on your building, since exclusion and prevention are also key IPM practices.

Photo credit: BillSmith_03303

Openings such as this one provide access for squirrels, raccoons, mice, rats, birds, stinging insects, bats, snakes, … Photo credit: BillSmith_03303

 

No rodenticides or other poisons are legally registered for squirrel control. Although a variety of repellents and devices make marketing claims about driving squirrels from buildings, their efficacy is questionable.

To prevent future problems, reduce squirrel access to the building by keeping trees and tree branches at least 10 feet away from the structure and make sure all vents are made of animal-resistant materials.

For information on IPM for nuisance wildlife, refer to Beasts Begone!: A Practitioner’s Guide to IPM in Buildings  and Best Practices for Nuisance Wildlife Control Operators.

(Adapted from Controlling Squirrel Problems in Buildings by Lynn Braband, NYS Community IPM Program at Cornell University)

Skip to toolbar