Crow control in Tokyo

Tokyo as been waging war on its crows for eight years.  The crows sometimes dive at people, and they "cause technological havoc. They nest in utility poles and cause blackouts; they even steal fiber-optic cables to build nests, sometimes disabling parts of the broadband network."

But despite fighting the crows for eight years, and spending millions of dollars, crow populations in Tokyo climbed 21% from last year to 21,200 this year.

"The crow budget for 2009 is about $700,000," says Tokyo's crow czar. "The year before, it worked out to around $50 for every crow killed. But we have to spend this money because people are complaining."  He says the city's garbage attracts crows from surrounding areas.

Some of the money has been spend on making garbage less accessible to the crows, and on improving garbage disposal.  The city also has created huge traps, which catch mostly young, inexperienced crows.  The crows are removed from the traps and gassed.

The NPR story concludes with the comment: "finding the right balance between man and nature isn't easy."

Attitude adjustment needed

Ever since Hitchcock's film, The Birds, there's been a certain amount of hysteria about our feathered friends,  when they get a little aggressive.

Obviously, by Tokyo Official's own admission, garbage is the cause of the problem.  If they are unable or unwilling to control that cause, crows and rodent pests will continue to be a problem.  If crows are damaging electrical equipment, then equipment should be redesigned to be "crow proof."

Part of the answer lies in educating the public, so they learn to live with crows, and even enjoy them.  These are highly intelligent animals.  Recently, one species of crow was found to be making and using tools. They are like a nation of immigrants, living silently among us.  Except we object  when they are not so silent or invisible. "Finding the right balance" might involve an attitude adjustment.

Learning about crows, and interacting with them, can be a pleasure.  I have tried calling to crows, imitating their voices.  It always gets a reaction.  Even looking at crows tends to upset them, since in my town they depend on going unnoticed.

I'm not sure why crows sometimes harass people in Tokyo.  I know they will defend their nests, by swooping at people who approach their nest.  Destroying nests would be more effective than trapping crows.

They may also just be trying to get food.  They may have learned that by swooping at people who are snacking, the snacks will be dropped.  In this case, it should be possible to "teach these crows a lesson."  Some bear control people in western states of the USA are taking this "behavioral modification" approach--shooting painful pellets at bears, and otherwise teaching them that freeloading doesn't pay. 

Crows are also known to "hold a grudge" against individual people.  Researchers went about trapping crows, while the trapper wore a Dick Cheney mask.  Later, when other researcers donned the mask, crows began to harass them, indicating that crows are capable of recognizing the face of an individual person.  

This behavior is called "mobbing," seen often in the wild, when crows chase and harass hawks or owls.  Crows are mobbed in turn by birds like redwing black birds, or eastern kingbirds.  Mobbing is a behavior that has long puzzled scientists who study animal behavior, because it seems to be "altruistic"  It exposes the mobbing birds to danger, while not benefiting them directly. 

So many of the pest control efforts I read about are ineffective.  The solution usually is just controlling access to garbage or food.   And nothing beats understanding the behavior of the animal in question.