Why do the wild-animal trackers always use such big tracking devices when there are much smaller ones?

Dear M.A.:

Whenever I watch a wild-animal documentary such as those on KPBS or the Discovery Channel, I'm appalled at the huge size and awkwardness of the radio collars they snap around the animals' necks to track them in the wild. With all the technological advances we've seen lately (after all, the Humane Society can insert a small microchip into your dog to identify it), why aren't the scientists in the wild more up to date? Are there any plans to change to more modern methods?

-- Kirsten, Pacific Beach

Well, Kirsten, about the only solution to the problem is to attach a big old extension cord to the bear's collar and plug it in back at wilderness-scientists headquarters. The difference between the microchip in Spot and the collar on a bear is that the collar is a transmitter, the chip just sits there until it's scanned by some other device. To transmit a signal so the animal's whereabouts can be tracked, you need a power source. Most of the collar is batteries. The more batteries you have, the stronger the signal and the longer it will last. What we need is better battery technology. Or maybe we can get the bear to wear a solar-panel hat.