Most travelers go to national parks to see wildlife, artifacts and pristine, breathtaking expanses of nature waiting to be explored.

But instead, some visitors have recently been feasting their eyes on heaps of trash, vandalism and even illegal immigrants.

Park rangers and preservation advocates say crunched budgets, staff shortages and new post-Sept. 11 requirements are stretching the system too thin.

“Parks attempt to place their top priority on the protection of visitors and resources,” said Jeff McFarland, executive director of the Association of National Park Rangers (search). “But the budgets have become so constrained that it’s extremely difficult.”

Many rangers lament that they simply can’t adequately watch over the country’s natural wonders and the guests there because they have too few park personnel to keep track.

“We’re strapped. We don’t have enough eyes out there looking for things,” said one northeastern U.S. park superintendent, who spoke on condition of anonymity. “It’s not in keeping with our mission to allow this to go on and expose ourselves and our visitors to potential harm.”

The National Park Service’s (search) operating budget has actually increased slightly for inflation by about 2.9 percent a year since 1998, according to the National Parks Conservation Association (search), an advocacy group that’s been publicizing the budget and staffing concerns.

But insiders say the money isn’t close to sufficient for the added post-Sept. 11 mandates on the Park Service, including shuffling rangers around to protect the so-called icon or high-profile sites — like the Statue of Liberty and Mount Rushmore — when the color-coded alert level changes from its normal “yellow” to the elevated “orange.” And in 2004, parks got only a 1.5 percent boost to cover a mandatory 4.1 percent staff pay raise.

In 2003 alone, NPS spent $8 million on expenses associated with code orange levels, the National Parks Conservation Association reports. Other unexpected situations that require rangers' help, like the disastrous Western wildfires, have also taken their toll.

“Every time these rangers get detailed somewhere else, whether for homeland security or for special things like the space shuttle [Columbia crash recovery], they know they’re leaving the park short-staffed,” McFarland said.

The national parks’ budget and staffing restraints have been capturing public attention in recent years, especially after one young ranger was shot and killed in 2002 by drug smugglers crossing the Mexican border into Arizona’s Organ Pipe Cactus National Monument (search).

That same year, another ranger was gunned down by a national park visitor on Hawaii’s Big Island when the ranger asked the man to leash his dog.

The Organ Pipe Cactus incident was indicative of a larger problem the scenic site — identified by the Fraternal Order of Police as the most dangerous national park in the U.S. — has been having with rampant border jumping and drug smuggling.

In April 2004 alone more than 200 illegal aliens were arrested as they tried to enter the U.S., the northeastern park superintendent said.

Organ Pipe visitors Helga and Rich Foulk, of Ambler, Pa., found themselves right in the thick of the border-crossing phenomenon in April when they visited the preserve for the second time in three years. The couple was camping in one of the designated areas when the trampling of footsteps woke them up about 2 a.m.

“In the middle of the night, a group of 20 immigrants walked up to our tent. Our tent was right in the path of their trail,” said Helga Foulk, a 32-year-old engineer. “Both of us were very surprised. Once they figured out we were tourists, they walked on.”

That same trip, the Foulks were dismayed to find piles of trash that appeared to be left from the illegals along the way — thousands of empty water bottles, bits of paper, medicine vials, electrolyte packages and other garbage.

The National Park Service says it’s particularly worried about the problems at the border and is doing what it can to get them under control.

“The biggest issue we have with security is border issues,” said NPS spokesman Gerry Gaumer. “It’s a heightened concern. There’s a constant fear of drugs, illegal immigrants. It’s something we’re trying to get a handle on.”

Poaching, vandalism and arson are also security concerns.

“We’re here to secure the resources of the park,” the northeastern superintendent said. “The squirrels, the flowers, the waterfalls, the rocks can’t call 911 when they’re being damaged.”

The current total NPS annual budget is $2.5 billion, with $1.6 billion of that technically allotted for day-to-day operations. The problem, say Park Service experts, is that the homeland security expenses are coming from the operations money pool — meaning the business of running the park often gets short-changed.

“Demands on the parks have gone up, and the budgets have not,” said Blake Selzer, legislative representative for the National Parks Conservation Association. “Over the last couple of years, the problem has grown exponentially.”

For now, there are few answers or solutions in sight, and the park system is making do as best it can. Though recreational visits have dropped slightly in recent years, determined travelers say they won’t stop trekking to the national nature preserves. But their trips — and their moods — might be affected.

“I would go back, but I wouldn’t camp in particular areas,” Rich Foulk, a 36-year-old history teacher, said of Organ Pipe. “It made me a little depressed to think about what’s happening to things. It’s an incredible park, and it’s being ruined.”