Oh, to be a toad crossing the road in Roxborough!

Like toads everywhere, they obey a timeless rite of spring, emerging from their muck at the first warm rain to hop straight for the nearest nuptial pond to breed.

In this case, that would be the Roxborough Reservoir.

But also in this case, Port Royal Avenue - with its steady car traffic - amounts to a sort of no-toad's-land blocking their path.

All too often, where the rubber meets the road, it also meets the toad.

To the detriment of the latter. As if their cousins weren't in enough trouble - up to one-third of amphibian species worldwide are in danger of extinction - the toads used to suffer a high death-by-squishing rate on this stretch.

But now, a curious thing happens.

On rainy spring nights, patrols of a dozen or more volunteers, with flashlights and reflector vests, walk the Roxborough road, picking up hopsters and carrying them across the blacktop.

These aren't the only do-gooder toadies. Similar amphibian rescues occur from the country roads of Chester County to the green vales of England.

The Brits are so enamored that they've mapped 700 toad-crossings on Google Earth, and "toad patrols" regularly converge to handle the blitz.

At the Delaware Water Gap National Recreation Area, officials actually close a road to allow salamanders, frogs, and toads to cross unscathed.

It keeps things safe not just for the critters, but also for the parents and kids who show up to witness this slimy Serengeti of animals.

"It's a special moment," said spokeswoman Deb Nordeen.

Near Sumneytown, Montgomery County, science teacher Kathy Leber and some of her students walked Swamp Creek Road recently, carrying 68 salamanders to safer ground.

Then on Monday, she joined a group in northern Chester County that for several years has been safeguarding the spring hop across St. Peter's Road in North Coventry Township.

The scene resembles a kind of amphibian flash mob. Salamanders were already heading back to the woods, while "frogs and toads seemed to be going in both directions," Leber reported. "Their voices were an amazing cacophony of trills, grunts, and croaks."

To be sure, this can all get a tad nutty, drawing its share of smirks - and even angry responses from drivers.

But amphibians have been hit hard by humans. Only half of the wetlands that existed before Europeans arrived in America remain today.

Their waters have been fouled with pesticides, introduced species outcompete them for food, and their skin can get scorched by sunlight streaming through a thinning ozone layer.

Compared with such perils, the automobile was once deemed incidental. But scientists began to accord it new status as an amphibian death machine after two researchers tallied the carnage along a country road - averaging 3,207 vehicles daily - in northern Denmark.

Writing in 2001, they found that an amphibian attempting to cross had a one-in-three chance of being flattened. And that was on a lucky day.

"A lot of us looked at that and said, 'Yeah, maybe we ought to be paying more attention to this,' " said Michael Adams, a research ecologist with the U.S. Geological Survey.

In a subsequent U.S. project involving spotted salamanders, researchers found that if more than 10 percent wound up as roadkill every year, the local population could crash.

That seems to have happened in North Jersey at one of three crossings that researchers from the state and two conservation groups have been monitoring since 2002. One is on the well-forested Shades of Death Road.

On a busy night, a thousand or more amphibians can try to cross these spots, said MacKenzie Hall, a biologist with the Conserve Wildlife Foundation. Some are listed by the state as threatened or endangered species.

But during just one two-hour period, with only 34 cars going by, as many as 71 percent of crossers were killed.

For a while, traffic was detoured, but then the researchers realized they were sending cars through another migration area they hadn't known about. So they went back to being crossing guards.

Still, within a matter of years, they shut down one of the survey spots; few amphibians were left.

What ups the risk for creatures like toads, frogs, and salamanders is that they're so-called explosive breeders. Instead of willy-nilly breeding over a matter of weeks, the first few warm and rainy nights of spring will bring most of the population out en masse.

In this region, it often happens in late March. So last weekend's warm weather surprised everyone.

In Roxborough, Lisa Levinson, an animal activist and artist who started the toad project, was just setting up a schedule, intending to start patrols tonight.

But during Monday evening's warm showers, toad mayhem erupted.

Fortunately, someone checked, and the call went out. Volunteers raced to the area and began stuffing them into wet sacks for mass transport.

Within several hours, they saw or helped 600 toads cross the road. Meanwhile, about 200 wound up under the tires. By morning, the group knew, the carcasses would be gone, cleaned up by possums and other predators.

Most of what had crossed Monday night were males, and the next night they were trilling loudly from the phragmites-thick water of the abandoned reservoir.

Within moments of starting down Port Royal, Nicola Baker, 19, of North Wales, bent to pick up a toad that had hopped in front of her.

She was with her father, Brett. Citing their pet cane toad at home, they said they wanted to help.

Starting today, the group has a permit from the Streets Department to close portions of several roads when needed. Meanwhile, they waved flashlights to slow motorists.

Many in the neighborhood know what's up. One driver rolled down his window and called out, "Frog time?"

Jessie Zahner of Roxborough, on her way to the gym, pulled over and declared it "cool to see so much nature in a big city."

Debbie Carr, an environmental educator with Fairmount Park, said the effort had been a "volunteer magnet." Last year, about 100 people participated.

Levinson said she had been astonished by the response and could only think it had to do with people finding toads cute and harmless, perhaps associating them with fairy tales.

She said the group planned to keep coming out every night for the next few weeks.

For the toads that make it across to the reservoir, it's a frenzied reproductive moment. The males mount the females so they can fertilize the eggs - up to 20,000 - as they emerge.

The reservoir will be filled with long, gelatinous strands - each coiled like an old telephone cord - studded with eggs.

Soon, the water surface will be vibrating with tadpoles. And within weeks, when they grow their leaping legs, they'll embark on another mission improbable.

They'll have to get back across the road.