FALMOUTH — The 41-acre River Point Conservation Area has a lot more than streams, ponds, rolling fields and trees.

The town-owned tract also has rare plants, butterflies and moths, beavers, otters, porcupines, snakes and mice.

Just how many became a little more clear this weekend, as dozens of volunteers fanned out across the wooded open space and took part in a “BioBlitz,” an effort to quantify the diversity of the area.

“It’s a three-dimensional look at one of our most important conservation properties,” said Robert Shafto, Falmouth’s open space ombudsman and the driving force behind the BioBlitz.

A BioBlitz is not meant to be all-inclusive, said Patrick Keenan, a researcher with the Biodiversity Research Institute in Gorham, which worked with Shafto to develop the effort – which started at sundown Friday, continued until about 2 a.m. Saturday, resumed a few hours later around sunup and then wrapped up in the late afternoon.

“Even in 24 hours, it won’t be exhaustive,” Keenan said, noting that animal occupants vary widely by season and even two or three weeks ago, the inventory would have been markedly different than what turned up this weekend.

Keenan said a variety of methods were used to count the different species in the conservation area.

Plants were catalogued by observation. Moths were attracted to a bright light at night. Birds were caught, banded and released. Mammals were either observed directly or their tracks were spotted.

Shafto said the survey turned up some rare plants, including the Hollowstem Joe Pyeweed, a plant that grows in dense clumps and is found in only about 20 other spots in the state. Researchers will continue trying to identify all the moths that were caught and the butterflies and birds that were spotted.

“It was not only significant what we saw, but what we didn’t see,” said Shafto, who was struck by “the absence of bats. The bats are gone.”

Shafto said he and others expected to see fewer bats than they might have a few years ago, when a fungus began decimating colonies along the East Coast. But he didn’t expect to see no bats at all, especially along a river corridor where bats would thrive, feasting on insects at night.

“That was quite shocking,” Shafto said.

Shafto said the results of the BioBlitz will help the town refine its management plan for the conservation area. For instance, the Pyeweed and some other rare plants need full sun to thrive, he said, so the town will likely try to control tree growth around the area where the plants are located.

He said he may also try to do BioBlitzes on other open spaces in town to help get a handle on the non-human population of Falmouth.

“It’s a great way to get a real good picture of what we’ve got,” he said. “And we had a great deal of fun.”

Staff Writer Edward D. Murphy can be contacted at 791-6465 or at: [email protected]