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Spider Delight: Collecting Arachnids in Colorado

By Frank Graham Jr.

posted 4/8/02

An amateur is, literally, a lover. For centuries now, amateur birdwatchers, amateur butterfly chasers, and amateur plant collectors have made major contributions to science. Spreading out over the landscape in pursuit of the wild things they love, they supply a wealth of material on distribution and behavior that helps fill critical gaps in the catalog of our nation's biodiversity. But amateur spider seekers have been rare. Now the Denver Museum of Nature and Science is truly casting a wide net for the lowly and despised. By assembling an army of volunteers for its Colorado Spider Survey, museum scientists hope to get a handle on the numbers and whereabouts of the state's eight-legged critters.

"We just don't know what impact the human population's growth and development has on under-studied groups like spiders," says Paula Cushing, the museum's curator of insects and spiders. "So starting in 1999, we worked for three years with Colorado State Parks to sponsor training workshops all over the state and teach interested people how to locate and collect these arachnids."

Nearly 500 men and women attended the workshops. Experts taught them to collect specimens in small film canisters, preserve them in rubbing alcohol, drop in labels noting the place and date of capture, sort them into families and sometimes species, and ship them to the museum for further identification and storage.

"A variety of volunteers showed up," Cushing says. "Teachers and other professionals came, and so did parents who home-school their children and want to teach them more about the natural world. Several people signed up to try to overcome their fear of spiders. I guess it worked. They told me afterward it was no longer a problem for them."

Cushing prepared a handbook for the workshops, outlining collecting methods such as sweeping vegetation with a net, looking under bark or rocks, and beating tree branches with a stick so that spiders tumble from the foliage onto a cloth below. She also stressed the need to get permission before venturing onto federal, state, or private property, as well as personal safety.

"If you lift up logs or rocks," Cushing wrote, "stand behind these objects and lift the top of them toward you, so that if you expose something 'Potentially Nasty' (i.e., rattlesnake, scorpion, centipede, etc.), the P.N. creature will move away rather than toward you."
About 70 participants decided to remain involved once the workshops had ended, and several people have taken on research projects of their own. For example, Margaret Geick of Denver is helping Cushing develop a key to funnel-web spiders in the Agelenidae family; it will include physical variations found in Colorado specimens. Nina Shilodon and Steven Bonham, a couple in Golden, collected a rare ant-eating spider called Zodarion rubidium, which is new to the American West.

"We heard about the workshops and thought, 'This is really cool!'" says Shilodon. "It has opened up an entirely new world for us. It helped us understand microhabitats--all that can go on in a small area like a backyard or a parking lot. And looking at spiders under a microscope is a revelation--the claws, the eyes, the segments of the legs. At first our friends couldn't believe we were actually collecting spiders. But now they bring us spiders they've collected in jars!"

Shilodon and Bonham say they have found a life-long endeavor and look forward to buying a good microscope for their home. Enthusiasm of this kind leads Paula Cushing to believe the survey will extend over a decade and turn up 600 to 1,000 species, some perhaps new to science. She also foresees an electronic database and a field guide to Colorado's spiders.

"Volunteers have already sent in more then 20,000 specimens," Cushing says. "We've identified 233 species so far, two-thirds of them new to the state. At first most of the specimens came from around houses and neighborhood streets. Now we have more of an ecosystems survey, with volunteers exploring alpine areas or riparian wetlands. I think the survey is making people more aware of the great diversity of life around them."