In article , "bthache"
wrote:

Hi Group,
I'm new to this newsgroup but I'm really hoping someone here can help me.
Last spring, for the very first time, when the snow melted, we realized that
all the bark had been chewed off of our willow tree (very young tree.. only
3 feet high). Then, we started seeing trees or branches all over town here
that had been chewed. Anything that had been under the snow was completely
stripped and had little teeny tiny chew marks. This morning, I noticed the
branches on my cherry bushes (just planted last summer) have the same damage
and I don't know if they'll survive.

Can anyone recommend a way of protecting these trees and bushes? I have new
bushes coming to be planted this summer and don't want the same thing to
happen. Any help will be very greatly appreciated!

--
Tammie

This behavior of some rodents is usually caused by a population explosion
due to lack of predators, combined with winter food shortage. Population
explosions also occur in areas where there is heavy usage of insecticides.
Many insect-eating predators also eat voles, & poisoning the insects
discourages predators & sets up an environment increasingly conducive to
rodents. Vole populations are also defined by how much grass seed is
available in its season. Reducing the amount of grass spring through
autumn reduces the number of voles desparate for something to eat in
winter. A good healthy amount of seeding grass actually induces voles to
go into estrus & reproduce like, well, like voles. But a lack of grasses
makes them go into sterility mode. There are other unknown factors that
cause temporary vole population explosions that do not last very long --
so a problem in one year might not be repeated for many years to come.
Though with lack of predators combined with lots of seeding grass, expect
the problem every winter, as they tend to strip bark only in winter
wherever there are no predators to catch them at it or to reduce their
numbers so that other food resources suffice. Voles often do it from under
snow, burrowing right through the snow to feast on bark of young trees
without themselves being exposed, though most predators aren't fooled & an
hear their movements in the snow; owls can even see their heat-signatures
through snow.

Reintroduction of predators is the only serious way to control the problem
over a large area, meaning a greater respect & encouragement for snakes,
merlins, owls, skunks, possums, racoons, foxes -- even toads do great harm
to rodent populations by eating unwise adolescents. Sometimes all it takes
is a ground-level birdbath to get your garden on the "rounds" of a possum,
who'll gobble down any night-foraging rodents while they're stopping by
for a drink of water. Even chickens keep down rodent populations, if you
can have "garden chickens" outside of pens, & housecats are really quite
good if outdoor oriented & not too unhealthily fat & spoiled by too much
storebought stuff that eventually makes it hard for them to pee & is no
favor to cats. Some smallish dogs like the Besenji & of course the rat
terrier also do away with rodents with wonderful dispatch without
themselves being too harmful to gardens. Besenjis have been known to
pursue prey right up into trees.

A garden or orchard that has become a bird sanctuary has fewer
small-rodent problems (though large rodents such as squirrels like some of
the same conditions as the birds). Many orcharders do everything they can
to discourage birds & poison insects, so of course they end up with mice
or voles that debark the trees. Gardeners should be more welcoming of
birds of all kinds.

Rodents are themselves usually too smart for poisons, having a system of
testing new potential food resources & remembering if anyone got sick.
When it is successful, poisoning rodents also inevitably poisons the
predators who capture spaced-out sickly rodents first, & in the long run
this leads to happier healthier rodent populations without predators.

Lower trunks can be barriered with rodent-proof screens of metal or
plastic. The sundry paint-on or spray-on repellant products tend not to
work, because rodents will climb above the worst-tasting bits, or just
won't mind the bad taste if they're desparate enough to eat bark in the
first place. But some people swear by produts like rubberized Bitrex that
adheres to tree bark through an entire winter & makes it taste extremely
bitter. It can't work any better than eggwhite with scads of cayenne
pepper & painting the lower extremities of the trunks, except the homemade
taste-destroyers need reapplication after every single rain.

Allegedly, baiting voles with sorghum or peanut butter or cooked rice,
mixed very liberally with vitamin D, stops them from reproducing & makes
them unhealthy because they start expelling calcium from their bodies at a
great rate & it mucks up their hormone systems, yet is harmless to
predators. I've never read a serious study of whether that works though, &
until I see such a study I'm assuming there's every chance this is a "safe
organic alternative" SCAM with the same effect as those ultrasonic &
subsonic devices praised by the manufacturers & shown universally to have
no effect whatsoever in controlled studies.

For large territorial rodents like squirrels you can bait them away from
bark-eating behavior by providing them with better food -- they protect
their food resources from rival squirrels so populations do not explode.
But this doesn't work for mice that tend always to expand their population
slightly beyond the amount of food available to sustain them, & providing
them tastier options than their last-choice of bark will just expand their
numbers. Encouraging predators is really #1, followed by barriers. The
third option is traps. Since these have to be placed exactly along their
trails, traps are not terribly effective, or they ARE effective but only
if you have so damned many traps they're themselves in the way & a
nuisance. But voles leave little piles of droppings everywhere they like
to eat, so those would be your clues where to set traps.

One hopeful thing is that voles really don't eat bark of mature trees
unless starvation has forced them to extreme behavior. They're primarily
going to harm saplings. If you can keep them off a little tree until its
no longer just a tender-barked young thing, the matured tree will
thereafter be safe except in an unusually harsh starvation winter in the
wake of overpopulation.

The other thing to worry about is that it isn't rodents at all. There are
some kinds of beetles that live just underground & by night eat bark down
to the bones of the tree, but also eat the bark off roots. So you might
want to take a good look for vole-droppings (they leave lots of them where
they eat) & be grateful if voles is all it is!

-paghat the ratgirl

--
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
-from Peter Newell's "Wild Flowers"
See the Garden of Paghat the Ratgirl: http://www.paghat.com/