As if being covered in inch-long, needle-sharp spikes weren't protection enough, Saguaro National Park's signature species is getting some additional protection.

By injecting radio frequency identification tags (RFID) into saguaro cacti, park managers hope to stem a rash of cactus thefts from the park.

"Deterrence is the biggest objective for putting microchips into saguaros," said Bob Love, chief ranger for the Arizona park. "If people know that we are doing something electronically then they are less likely to steal them."

The RFID tags are the same ones used in pets or other animals. Each $4 chip will be inserted into the saguaro using a needle and should last the lifetime of the saguaro, which in some cases is more than 200 years.

There are over one million saguaros at the National Park, but Love and his fellow rangers don't plan on tagging them all. Just those in their prime. The young and old cacti aren't targeted by thieves because they are either too small or too large for easy transportation.

Thieves typically target saguaros between five and seven feet high, which are about 40 years old. After digging out the shallow root system the thieves then roll the cactus up in a piece of carpet to protect themselves from the needles before loading the succulent into a vehicle and driving off.

The thieves then sell the saguaros to nurseries or land scape architects, usually for up to $2,000 each. There is no law against buying or selling saguaros, but taking Park Service property is a crime. Two men were recently arrested after digging up 17 saguaros during the night. They face up to a year in jail and a $5,000 fine.

The RFID chips don't sound an alarm or allow park managers to track stolen cacti. In fact, the tags can only be detected about a foot away using a special scanner.

"Some people think that we can track them with GPS," said Love. "That's not the case, but we are happy to let people think that."

Park officials periodically sweep nurseries to find stolen cacti. The RFID chips will allow officials to determine whether a particular cacti was legally obtained or not.

Saguaro National Park officials got the idea to identify NPS saguaro cacti from a similar program run by officials at the nearby Lake Mead National Recreation Area, outside of Las Vegas.

Over the course of several years one man made off with more than $1 million worth of barrel cacti. In an effort to deter others from absconding with the spiky succulents, Alice Newton implanted thousands of pit tags into barrel cacti, but also other, undisclosed species to deter theft starting in 2000.

Data from the last two years is still being analyzed, but the program appears to be working, even though no subsequent arrests have been made. In Newton's view, that's a good thing.

"The whole point is to prevent people from doing this in the first place," said Newton. "We judge our success by prevention, not by catching someone."

It's a level of effectiveness the officials at Saguaro National Park hope to achieve as well.