How to find a flying squirrel: Citizen scientists are enlisted to help scientists.

Such citizen scientists — volunteers who perform research alone or alongside professionals — have contributed to science since the 1800s. They discovered Comet Hale-Bopp, improved navigation charts for sailors, set their computers to search for extraterrestrial life and, in the case of Erin Brockovich, figured out what was polluting a community's water. The term "citizen scientist" was coined in a 1979 issue of New Scientist, according to Muki Haklay, a University College London professor and the director of its Extreme Citizen Science group,

How Hale and Bopp found their comet

What’s new is that professionals such as Tremor, who works at the San Diego Natural History Museum, find citizen scientists to be an important adjunct to their classic approach to investigation. With technology so easily available, more ordinary people than ever are participating in scientific research.

According to Jennifer Shirk of the Citizen Science Association, a group founded in 2013, mobile and Internet technologies have fueled a huge growth in participation focused not only on local issues such as the San Bernardino squirrel but also on larger ones such as climate change.

The association and others like it in Europe, Australia and elsewhere have formed in recent years to promote citizen science, assist in its practice and build a community around it, Shirk said.

The U.S. government is also getting involved. In September, the White House held an online forum to highlight contributions that citizen scientists have made to agriculture, health and other fields, and launched a website that federal agencies can turn to for help in organizing projects.

That event, Shirk said, was “a major vote of confidence” in the value of volunteers.

Citizen science can yield information that is otherwise difficult or impossible to come by, said Alison Cawood, coordinator for citizen science at the Smithsonian’s Environmental Research Center in Edgewood, Md. “There is no way that one lab can have enough people to answer questions that require lots of data collection over a short period of time or over a large geographic scale. No lab can afford or reasonably manage the efforts of that many people, nor can they put effort into hiring people they may only need for a day or a week per year,” she said. “Only volunteers make sense for projects like that.”

Cawood does recruiting on SciStarter.com, a citizen scientist website, and volunteer websites including Idealist.com. She also emails new opportunities to past volunteers and to those who have expressed an interest in participating.

Using these methods, she found about 100 volunteers for a study last summer of a parasite affecting mud crabs in Chesapeake Bay. Most of the participants collected crabs in the field, while a handful worked alongside paid staff to measure each one and count how many contained the parasite. Cawood said a postdoctoral fellow is using the data to study how the parasite evolves and to better understand invasive parasites and diseases in coastal marine ecosystems.

A project named eBird is a vivid example of the scale of work that can happen when citizen scientists get involved. The online study was launched in 2002 by the Cornell Lab of Ornithology and the National Audubon Society. Since then, said the lab’s Christopher Wood, more than 250,000 people from every country in the world have submitted 300 million records of bird sightings for inclusion in a database.

“When you put that much data in the hands of researchers and scientists,” Wood said, “you can answer a huge variety of questions . . . [that] you wouldn’t be able to answer with smaller-scale studies.”

In January, for example, Wood’s team announced that eBird data had helped researchers model the migration of 118 species, spanning the Western Hemisphere, for an entire year. Such a project was previously impossible. “Species ranges are no longer polygons on a map” based on expert opinion of where a species might be found, said Wood’s colleague Brian Sullivan. Now, he said, those ranges can be based on field observations “that give us an idea of how many of each species we can expect to find on a particular day in a particular place.”

Wood said such data can help improve conservation efforts. For example, he said, the Nature Conservancy, in collaboration with farmers in California, uses eBird data to time the flooding of rice fields for precisely when migrating shorebirds need such habitat for feeding and resting.

In addition to providing sheer numbers and geographic range, citizen scientists can perform tasks that hardware or software can’t.

“The detection and identification of birds is a highly nuanced process that machines aren’t capable of yet,” Sullivan said. Only humans can discern birds by what they look like and sound like and then classify them according to species, for example. “Without humans, eBird would not exist,” he said.

Citizen scientists can also cause problems for researchers. For example, Cawood said, volunteers can create biases in data when they make observations only on weekends or during nice weather, distortions that professional scientists generally don’t cause

“Volunteers do what fits with their schedules, which is perfectly reasonable,” she said. “There are ways to deal with this” — through statistics or the design of experiments, for example — “but it can present a complication. You just aren’t always sure what you are going to get with volunteers in the way that you are with staff you have hired specifically to do a job.”

Citizen science can have a positive impact in labs as well.

Professional scientists are using tools from Public Lab, a nonprofit that got its start by designing do-it-yourself scientific instruments — including kites equipped with digital cameras — so volunteers could survey damage caused by the 2010 Deepwater Horizon oil spill in the Gulf of Mexico. Because of Public Lab, ecologist Chris Fastie of Middlebury College in Vermont said, he can modify a camera to take infrared photos, which are used to analyze plant health, for less than $100.

“I can do it without using grant money, and students can use the cameras for undergraduate projects or graduate research,” he said. “Commercially available equivalents cost thousands of dollars, so most students never get their hands on one. [Public Lab] changes the equation for who can participate in making this type of scientific observation.”

For Luisa Serrano of Yucaipa, Calif., who has seen the San Bernardino flying squirrel at her cabin near Big Bear Lake, being a citizen scientist is a civic duty. A lifelong birdwatcher and eBird contributor who let Tremor set up remote cameras, seed feeders and hair-collecting tubes at her cabin, she said volunteering for science gives a greater purpose to her enjoyment of watching wildlife.

“If you think of [the environment] as our life-support system, then we have a huge obligation to take the best care of it that we possibly can,” she said. “You may not live to see the final good results of your participation, but at least you’re contributing, and I think that’s important.”