They come in household goods, even animals. But some worry they also could penetrate human beings. They are called RFIDs for radio frequency identification. The tracking technology is complex, but it's spreading. Some worry it could go too far.

This is where Madison's tropical birds get lost. Or do they?

"If an animal comes in, we would chip it and that's their permanent identification," zoo veterinarian Mike Petersen says.

A microchip inserted under the skin allows staff to track birds, or any other animal, by reading the chip's number.

"With birds in the past, we always used to use leg bands. This is much cleaner for the bird. It's not something that can get hung up on anything. It's a safer product for the animal," he says.

You can see how tiny these tags get. Some worry this kind of small but sophisticated technology could find it's way into humans.

Assemblyman Marlin Schneider says, "there are positive things but, when it's used for monitoring and keeping track of every place we go then they've crossed over the line."
Schneider brought his concerns about radio frequency identification before a committee on criminal justice and homeland security.

He's pushing a bill that prevents people from being forced to implant RFIDs in their bodies.

He says, "I have been arguing the issue of privacy for a long time. This is perhaps one of the most invasive technologies to come along yet."

But also perhaps one of the most useful in supply chain management.

"Definitely one of the objectives of the retailer is to have 100 percent availability of their products and this technology could help toward that goal," Alfonso Gutierrez of the UW E-Business Consortium says.

Any business in the supply chain can use these tags to track goods. An antenna reads a chip inside the tags, revealing much needed information.

"There is a major advantage in knowing where things are and what time they are in certain spots in supply chain," Gutierrez says.

He says some companies like Wal-Mart will require suppliers to implement this technology, making it already a part of your life.

The UW Madison has a lab dedicated to RFID technology.

A conference exploring the issues surrounding RFIDs in industry will take place next month in Waukesha.