If acorns are poisonous, why don't squirrels die? 11/30/2008 12:19 AM By BILL HAYES Columnist
As mentioned before in this column, we get all kinds of questions in the Master Gardener office at the Aiken County Extension Center. Many of the questions are routine but occasionally we get one that needs plenty of research. The other day we received the question: "Are acorns poisonous"? Most of the time we answer without questioning the caller but in this instance we asked why they needed to know. If horses or cattle are involved, we have to direct the question to a higher authority. The caller responded by telling us that they had spent most of the night tossing and turning because, if acorns were poisonous, why didn't squirrels die?
This seemed like a question that might keep me up too so I decided to do some research. My first source for information is always the Clemson HGIC website but it had very little information on acorns. I then turned to the Internet which has just about everything. I found a few articles that indicated that some acorns were poisonous to certain animals but I found many more articles that not only said that they were good to eat but they also provided recipes for acorn bread and roasted acorns.
New Zealand and West Virginia must be having problems with sick or dying cows and sheep because I found several articles about the effect of acorns on livestock. The articles referenced red acorns as the culprit and discussed how the toxins in the acorn can break down their digestive systems. Red acorns have more than double the tannin content of white acorns. To distinguish the two, red acorns come from pointy leaved oak trees like the red, black, pin and willow. White acorns come from the white oak tree that has rounded leaves. The swamp, bur and water oaks fall into this category. Horses can have problems with red oak acorns if they eat too many. To be safe, keep all farm animals away from acorns especially if you can't distinguish the difference between red and white.
I found all sorts of stories about Native Americans eating acorns as part of their daily diet. I also found one article that said that the average life span of the American Indian was 30 years but made no reference to acorns as being part of the problem. Because of the high tannin content in red acorns the bitterness was probably strong enough to discourage all but the very hungry.
I finally located an article about squirrels and acorns. It turns out that gray squirrels have an enzyme in their system that protects them from the effects of red acorns. It doesn't change the taste, which is very bitter, but it does prevent a toxic reaction in the stomach. Most squirrels in Aiken are gray but we do have a few red ones too. Red squirrels are not as lucky as the grey and have no protection against the toxins in red acorns. Maybe that's why we have so few red squirrels.
Most of our squirrel calls are from non-squirrel lovers. They want to know how to get rid of them. There is usually a bird feeder in the discussion and bird feeders are squirrel magnets. Many are sold as "squirrel proof" (excuse me for a moment while I try to contain my laughter)! Squirrels go to a special school to learn how to overcome "squirrel proof" feeders. Upon graduation they train other squirrels and soon the whole neighborhood has a group of Green Beret type rodents capable of breaking into Fort Knox. The simplest way to create a "squirrel proof" bird feeder is to offer items that the squirrels don't like. I would start with red acorns.
A well-fed dog will usually avoid acorns. That doesn't mean that they won't try one if it's available. The first bite will probably be the last because of the bitterness. A vulnerable dog will be one that is undernourished or fenced in with an oak tree in the yard. Too many acorns will cause digestive problems and a weakened dog or puppy could have severe consequences. Rake up the acorns if your dog has full access to them.
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