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November 7, 2008

One campus's solution for "Squirrels Gone Wild!"

Posted: 11:06 AM ET

Squirrels at the University of California-Davis have it made.

5300 acres of lush habitat.

The eastern fox squirrel is living large on the University of California Davis campus. Wildlife scientists will use a contraceptive vaccine to try to control the population. Photo courtesy UC Davis

More than a few crumbs from students and faculty who enjoy meals and snacks outside.

(And we're not talking the average "frugal student" ramen noodles and peanut butter and jelly. UC-Davis is home to The Robert Mondavi Institute for Wine and Food Science.)

With nary a predator, there's been a population explosion of the non-native eastern fox squirrels, from zero to about 400 in the past seven years. And now there's worry the critters might get more aggressive, biting the collegiate hands that feed them. Squirrels can carry bacteria that is harmful to humans. And an unchecked population could become a threat to the regional economy, spreading to nearby farmland and chomping away at the local fruits and nuts.

When college officials searched for answers to these potential nuisances, they had to go no further than scientists on campus.

And as one might expect from a campus in California, the plan is to control the population with no harm to the animals involved.

Squirrel contraception.

"This new birth control method may potentially help control squirrels or other species, such as white tailed deer," said Sara Krause, a doctoral student in ecology who designed the plan.

"If we can test a birth control method and find it safe and effective, there's a possibility of it being a breakthrough method in both urban and suburban areas," she said.

Continued unchecked procreation and expansion of their territory could mean farmers and ranchers would put an end to the invasive fox squirrels permanently. Squirrels can do serious damage to almond and walnut orchards.

The birth control method being used is a vaccine, called GonaCon.

Krause explained that it's an immunocontraceptive vaccine, blocking the pathway to the production of sperm and eggs. One shot leaves the animals sterile for about two years. And the same vaccine works on both males and females.

(Now there's a concept that every female on the planet can appreciate.)

Krause and others have just begun placing 20-40 humane traps around the campus. The traps will be checked two to four times a day. On this first round, captured animals will be examined, marked with a nontoxic dye, and let go. The squirrels will be observed until next summer, when they'll be re-captured. Then, some will get the contraceptive injection, others a placebo. Again, they'll be set free to roam the campus.

If the experiment works as planned, the number of squirrels will decline to a sustainable number within ten years. And federal wildlife biologists could use the contraceptive on other prolific progeny producers.

By Marsha Walton, CNN Science and Technology Producer

Filed under: Animals • environment • science


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DJ   November 15th, 2008 11:09 am ET

Oh, I just noticed the shot works equally well on both sexes, I suppose there would just be a proportional decrease in the breeding population if it is a simple random sample, and probably wouldn't affect allele frequency in the population. Still, interesting stuff!


Mike   November 17th, 2008 12:56 am ET

For those who thinks this is crazy, believe me there are to many Squirrels! I have a walnut tree and they eat all the nuts and leave a large amount of shells and droppings all over my yard, I could count at least 25 in the tree at one time. Thats to many. They are just an other form of a rat for those who do not know. Anyway I may have to cut my tree down just to be rid of them. Truly we have a squirrelly problem. Pacific North West


Franko   November 17th, 2008 8:26 pm ET

In order to save your nuts, put a rat guard, around the trunk of the tree. It is a metal sheet, too slippery for the rodents to grip.

If the campus wants rodents, try the capybara
Can be trained to take the place of a seeing eye dog
Does not bark at night, or climb up your pantleg
Or 70 kilograms of burger meat for the local campus cafeteria.


mlburton   April 13th, 2012 7:14 pm ET

Moral Question? There are waaay too many and you must remember that along with the damage they do to homes they do carry there on host of critters that could possibly knock out a boatload of people. Did you ever hear of the boubonic plague? Rabies?Tick, fleas, need I go on? They are a danger in their own right!


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