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

November 29, 2016
by Mary M. Woodsen
Comments Off on Nature’s Herbicides and Lessons from Black Walnut Trees

Nature’s Herbicides and Lessons from Black Walnut Trees

You’re prepping your garden for winter, muttering about the sapling black walnut trees the squirrels planted on your behalf mere inches away — and the mother tree is in your neighbor’s yard. You know you can’t put off removing them: this might be the last year your loppers can manage the task.

Squirrels are pretty good at finding the walnuts they stashed here and there for winter. But they always miss a few.

Squirrels are pretty good at finding the walnuts they stashed here and there for winter. But they always miss a few.

Black walnuts get a lot of grief from gardeners. For those with small yards and a great love of tomatoes, the black walnut in a neighboring yard is bad news. But for the moment pretend you’ve got couple of acres, mostly meadow. Pretend the mama walnut tree in the hedgerow out back is framed by a couple of invasive ailanthus (aka tree of heaven) and some elderly pines and sugar maples. Pretend also that goldenrod, quackgrass, and garlic mustard are well-established meadow plants that push their way into your garden every chance they get.

And while you’re at it, pretend you planted buckwheat as a cover crop earlier this summer in some beds where weeds have held sway.

Buckwheat contains three allelopathic chemicals. Are they potential herbicides? Could be.

Buckwheat contains three allelopathic chemicals. Plus they grow really fast, out-competing many weeds.

What do all these plants have in common?

They’re alleopathic. That is: they have compounds in their leaves, roots, seeds, or stems that stave off other plants. True, some (think garlic mustard) will only hurt you. But some — buckwheat, for instance — will help. (Hint: click on the fifth bullet point when you open the page.)

NYS IPM’s horticulturalist Brian Eshenaur calls such allelopathic compounds “nature’s herbicides.” If you choose and use them, you might avoid the worrisome traits of conventional herbicides.

What worrisome traits? For starters, the potential for weeds to become herbicide-resistant. If using herbicides is the only way you’ve learned to deal with weeds, you could be in trouble. Could weeds (which, like plant diseases, qualify as pests) also become resistant to nature’s herbicides?

No one is sure. The research has just begun. But by way of example, consider this: insect pests become pesticide-resistant with relative ease. On the other hand, they don’t easily outsmart other bugs that evolved to eat them — which is why biocontrol is a key tenet of IPM.

Worried about walnut trees? Garlic mustard is acquiring a nasty reputation of its own.

Worried about walnut trees? Garlic mustard has a nasty reputation of its own.

Yes, black walnuts freely release their plant-suppressive chemicals. But even they have their soft spot.

Here’s what black walnuts are willing to live with:

lima, snap and soybeans; beets and swiss chard; corn; onions, garlic and leeks; parsnip and carrots; cauliflower; parsley; Jerusalem artichoke; melons, squash and pumpkins.

And here’s what they aren’t:

asparagus; cabbage, broccoli and kale; eggplant, peppers, potatoes and tomatoes; rhubarb; peas.

Where walnuts crowd too close, build raised beds with root barriers in the bottom — concrete or rubber patio blocks are one option. Hefty tubs are another. You could raise those beds even higher: built at waist height, they could keep your back happy too.

Worried about those walnut leaves that blow into your yard each fall? Can you add them to your compost? Have no fear. Exposed to air, water and bacteria, their toxic effect is history in two to four weeks. [1.]

Want to know more about shrubs and flowers that don’t mind walnut trees? Cornell Cooperative Extension is here to help.

Also, take a look at Eshenaur’s Weed-Suppressive Groundcovers. And consider that most of these plants are great when massed in perennial flowerbeds — and could provide welcome food and shelter for pollinators. Multitasking plants? They’re onto IPM.

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  1. extension.iastate.edu/news/2005/jul/070701; this site also lists some compatible and incompatible plants.
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