FEWER SLIP PAST BORDER U.S. OFFICIALS CREDIT MEXICAN TROOPS, NOT AMERICAN MINUTEMAN VOLUNTEERS.

Byline: Beth Barrett Staff Writer

The number of Mexican immigrants trying to illegally cross into Arizona has fallen sharply since highly publicized civilian patrols took up desert positions, but authorities on Wednesday credited stepped-up government patrols on both sides of the border for the drop in traffic.

At the Naco station in southeastern Arizona, where the Minuteman Project has focused its efforts this week, the U.S. Border Patrol reported making 74 arrests Tuesday, compared with 91 to 296 on each of the previous five days. A year ago Tuesday, there were 528 arrests in the same region, according to Border Patrol figures.

Mexican officials reported that the number of undocumented migrants dropped by half - from an average of 400 to just 198 - on the second day the Minutemen were watching.

``We've seen the numbers going down dramatically, but we attribute that to the Mexican military in the Naco-Douglas corridor,'' Jose Maheda, a U.S. Border Patrol spokesman in the Tucson region, said in a telephone interview.

``They're on patrol on the border,'' he said about the Mexican military. ``When we see their presence, we know something is going on. They're not commonly seen. From past experience when they're out there, apprehensions just plummet.''

Bertha de la Rosa of Grupo Beta, a Mexican government-sponsored group that discourages people from crossing illegally and aids those stranded in the desert, told The Associated Press that increased patrols by Mexican state police officers and her group were discouraging efforts to sneak across the border.

``The fact that we're not seeing them here doesn't mean they are not trying to cross,'' said de la Rosa, the group's coordinator in Agua Prieta, a Mexican town across the border from Douglas, Ariz. ``They say they will look for another place or wait awhile, but they are not giving up.''

Minutemen organizers initially promised that as many as 800 volunteers would participate at one time or another in the monthlong migrant- monitoring project. They say about 480 have shown up, but the number is not verified, and authorities were not keeping count.

``Look at the figures before we got here and the current figures, and do your own math,'' said Jerry McBrearty, spokesman for the Minuteman Project. ``We've proven that if you increase the resources on the border, it has an effect; it reduces the number of illegal immigrants.''

McBrearty said the project, which has brought international attention to the border problems, has resulted in a larger law enforcement presence on both sides of the border, accounting for the decline.

The volunteers themselves have made up to 50 observations of people attempting to sneak across the border, McBrearty said, and have reported them to the Border Patrol.

``Our intention is to draw attention to this on a national basis.''

Border Patrol officials acknowledged the recent decline in arrests, but attributed it mainly to Mexican military operations just south of the border. Officials said the Minuteman Project has only made their job harder by putting civilians in danger of encountering smugglers of drugs or humans in the canyons and mountain passes.

The U.S. Border Patrol last week also added nearly 200 temporary agents in the Tucson region, bringing the total to almost 2,400 agents for the region's eight stations. The agency is looking to hire 336 more permanent agents.

Maheda called last week's increase in agents part of a program begun in 2004 to bring in reinforcements under the Arizona Border Control Initiative.

He said that initiative is combined with other efforts, including the Be Alert program with a toll-free number to report crossings to the Border Patrol. Since advertising of telephone number began in mid-March, citizen calls have increased from about 300 a month to about 300 per day.

Glenn Spencer, a former Sherman Oaks resident who backed Proposition 187 and other attempts to stop U.S. benefits for illegal immigrants, said he has observed unprecedented activity from his home, just 1,100 feet from the border in Palominas, part of the Naco region.

``We saw Mexican military working on the road in one of these hot spots,'' said Spencer, who founded a nonprofit volunteer border patrol several years ago. ``There is a tremendous presence on Border Road that we've never seen before.''

The Minuteman Project has been criticized by federal authorities as disruptive and potentially dangerous, and other opponents have called it vigilantism.

``There is concern that groups like this are really acting as vigilantes who take the law into their own hands,'' said Araceli S. Perez, staff attorney for the Mexican-American Legal Defense and Educational Fund, in a recent interview.

``We're concerned there are private citizens who may have racial animus trying to enforce laws in violation of immigrants' rights.''

Migrant sympathizers say people unable to cross in Agua Prieta have begun arriving at shelters in Nogales, about 80 miles west, and in Altar, a town about 125 miles southwest, according to the AP.

Francisco Garcia, a volunteer for Altar's lone shelter, said most migrants dismiss the Minutemen as crazy.

``For us, it's clear to see things could get out of control because those in the migration business are not easily intimidated,'' Garcia said. ``We're afraid an aggression could escalate into an international incident.''

The Associated Press contributed to this report.

Beth Barrett, [phone]

beth.barrett(at)dailynews.com