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Cactus trackers: park rangers turn to a high-tech solution for combating cactus theft.

Two years ago, rangers at Saguaro National Park in Tucson, Arizona, were shocked to find 17 of the park's namesake cactuses missing. The saguaro (sa-WAH-ro) cactus is a tall, spiny plant--not the sort of species one would expect to pull a vanishing act.

The park rangers suspected that thieves had dug up the saguaros to sell on the black market. Their best guess was that the plants would end up in landscapers' nurseries.

It's illegal to move saguaro cactuses without prior approval from the State of Arizona Department of Agriculture--not to mention that removing any natural resource from a national park is illegal. This was the biggest heist in the park's history.

"We ended up surveilling the area, and we actually caught the two [thieves]," says Bob Love, the park's chief ranger. While they were relieved to have caught the culprits, park officials knew they had to do more to protect their prized cactuses. Now Love and his fellow rangers are turning to a high-tech tracking device to keep tabs on the park's cactuses and deter potential poachers.

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DESERT GIANT

The Sonoran Desert covers approximately 311,000 square kilometers (120,000 square miles) of Northern Mexico, Mexico's Baja Peninsula, Southern Arizona, and California (see map, p. 14). Saguaro National Park lies on the northern edge of this desert. A desert is a climate region that receives less than 50 centimeters of rain per year (see Nuts & Bolts, p. 14). To an untrained eye, a desert may seem like barren wasteland, but it is actually a thriving ecosystem. Many organisms in the Sonoran Desert rely on the saguaro cactus. Biologists at Saguaro National Park have been studying the area's saguaros since 1939. They have learned a lot about the cactus and its role in the ecosystem in that time.

"Saguaros replace tall trees here. So at every stage of the season, animals are using them," says Don Swann, a wildlife biologist at the park. For instance, Gila woodpeckers dig out cavities in the flesh of the saguaro and then live in the holes. Hawks make their nests where the cactus's large arms join the main stem. Insects and bats sip on the nectar and pollinate the saguaro's flowers that bloom in the spring.

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When the plant bears fruit in late summer, birds feast on the sweet flesh and transport the seeds in their droppings to new areas of the park. Once a saguaro has lived its full life cycle, which can last anywhere from 150 to 200 years, it will topple over and its woody ribs will be used by lizards, pack rats, and other mammals as a home or as a nesting material.

RIPE FDR THE PICKING

Swarm and his fellow biologists have noticed a trend in the park's saguaro population: There has been a surge in the number of baby cactuses since the 1960s. "They're replacing the large, older, very grandiose saguaros," says Swann. This younger generation of saguaros is now the perfect size for cactus thieves.

Older saguaros may be more than 3 meters (10 feet) tall and weigh as much as an adult hippopotamus. While it is possible to move a cactus that large, it would require a backhoe and other heavy equipment to do so. Instead, thieves are targeting young cactuses that are just 1.4 to 2.8 m (4 to 8 ft) tall. Two people can maneuver such small cactuses into the bed of a pickup truck. These are the cactuses that Love and the other rangers will monitor in their new program for protecting the vulnerable saguaros.

LAW AND ORDER

What's their solution? Simple identification tags, called passive integrative transponders, or PIT tags, which they will place in saguaros' flesh.

"The PIT tags are the exact same technology that people use for their dogs and cats," says Love. They are preprogrammed microchips encapsulated in glass or silicon about the size and shape of a large grain of rice. Each tag has a unique code, but no battery or other way to store energy. Instead, if a special wand is waved over it, the wand sends enough power to the chip to turn it on and retrieve its code.

With roughly 1.3 million saguaros in the park, it's too big a job to tag all the cactuses. Instead, rangers have decided to focus on ones that are small and near access roads--characteristics that make them prime targets of thieves.

The park rangers are partnering with students from Arizona's Vail High School to implant and monitor the cactuses. Students will put the microchips in the flesh of the cactuses and help fine-tune the data-gathering process. If another heist occurs, park rangers also will be able to use handheld scanners to see if any cactuses at nurseries were pinched from their park. Stolen cactuses will get returned to the park for replanting.

"The saguaro is the icon of the American Southwest," says Love. "This national park was set aside to preserve the saguaro cactus, so we're going to do our best to be vigilant in our law enforcement and patrols, and make sure that we're doing the best job possible protecting these giant cactuses."

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nuts&bolts

TYPES DF DESERTS

Deserts cover approximately one fifth of Earth's surface and are found everywhere, from Africa to Antarctica. There are four main types of desert.

Hot and dry deserts receive very little rainfall (mostly in winter), get very hot, and usually are located near the equator. Semiarid deserts receive more rainfall, are cooler, are farther from the equator, and are found in North America, Asia, and Europe. Coastal deserts are found in both subtropical and subarctic areas near oceans. Cold deserts get snow instead of rain, and are found on extreme southern and northern landmasses.

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PRE-READING PROMPTS:

* What is a desert? Where on Earth can you find deserts?

* Can you name three desert plant or animal species?

* Why would park rangers want to keep tabs on their parks' cactuses?

DID YOU KNOW?

* You may think that, with an area just over 9,000,000 square kilometers (about 3,500,000 square miles), the Sahara Desert is the largest desert on Earth. But it's only the second largest. The big winner is the interior of Antarctica. This cold desert covers approximately 14,000,000 square kilometers (about 5,400,000 square miles).

* The saguaro blossom is the state flower of Arizona.

* Saguaro cactuses have an extensive root system. The roots have special hairs that allow the plant to capture as much as 757 liters (200 gallons) of water from a single rainstorm.

CRITICAL THINKING:

* The special identification tags that the rangers at Saguaro National Park are using to help prevent cactus theft are also used for identifying lost pets. For what other applications might this technology be useful?

CROSS-CURRICULAR CDNNECTIONS:

LANGUAGE ARTS: The thieves have struck again! Two more of the park's cactuses have been stolen. Imagine you're a park ranger at Saguaro National Park. Use the information in the article to write a press release describing the two stolen saguaro cactuses, from where they were stolen, and your plan to track down the culprits--and prevent future theft.

RESOURCES

You can access these Web links at www.scholastic.com/scienceworld.

* Want to learn more about the different types of deserts? Check out the University of California Museum of Paleontology's online exhibit here: www.ucmp.berkeley.edu/exhibits/biomes /deserts.php.

* The Arizona-Sonora Desert Museum's Web site is full of information about the area's plants and animals: www.desertmuseum.org.

* Pima County, Arizona, has this Web site for kids with Sonoran Desert-related games, activities, quizzes, and more: www.pima.gov/cmo/sdcp/kids/index.html.

DIRECTIONS: Circle the incorrect word or phrase below and write the correct word or phrase below it.

1. A saguaro cactus is a short, smooth plant.

2. The Sonoran Desert covers parts of Northern Mexico, Mexico's Baja Peninsula, Southern Texas, and Oklahoma.

3. Thieves are stealing the old, large, saguaros to sell to nurseries on the black market.

4. Park rangers are using passive integrative transponders that they will wrap around the cactuses' bases to prevent further thefts.

Answer

1. short, smooth/fall, spiny

2. Texas, and Oklahoma/Arizona, and California

3. old, large/young, 4 to-8 foot tall

4. wrap around the cactuses' bases/place in the saguaros' flesh
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Article Details
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Title Annotation:EARTH: DESERTS
Author:Hamalainen, Karina
Publication:Science World
Geographic Code:1USA
Date:Oct 26, 2009
Words:1409
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