"An interesting aspect of northern butterfly ecology is that because some species are adapted to alpine areas, they only reach maturity every second year," notes Mark O'Donoghue, a Mayo-based biologist with the Yukon government.

To survive the elements in the Yukon -- like shorter summers and rugged, often inhospitable terrain -- many butterflies have adapted through changes to their life cycle, diet, habitat or other factors.

O'Donoghue says that some butterfly species are synchronized with each other and share the same schedule; they all hatch from eggs in the same year and take two years to mature, so there are only adults flying every second year. Other butterfly species have some adults flying each year, even though they take two years to grow.

"Many of these species are Beringian, which is one of the features that makes them particularly interesting to butterfly collectors," adds O'Donoghue.

Beringia was a vast area across parts of Eastern Russia, Alaska and Yukon that was free of glaciation during the last ice age. As a result, the region became one of North America's main refuges where plant and animal species could survive. Keno lies at the southernmost edge of Beringia.

"Beringian butterfly species adapted to high alpine peaks like those around Keno," explains O'Donoghue. "After the ice sheets receded the butterflies could migrate south, but many stayed restricted to these areas."

Another interesting aspect of butterfly ecology is how much they can be tied to specific food sources. "Many of these alpine butterflies are specialists and depend on certain plant species for sustenance," says O'Donoghue.

For example, Eversmann's Parnassians species lays its eggs on the Few-flowered Corydalis and the larvae feed only on its leaves. Once mature, butterflies are able to travel around to different flowers and become more generalists.

O'Donoghue summarizes the life cycle of the butterfly: "The egg hatches into larvae, and these are what we know as caterpillars. As caterpillars become bigger and bigger, their skin splits and re-grows perhaps four or five times. The final time this happens, the caterpillar begins to pupate and becomes a chrysalis. It's during this stage when the transformation into a butterfly occurs."

Though Beringian species are not rare, their origins and northern habitat make them unusual. Easy access to the alpine in the Keno area also means that these butterflies are more visible. While this creates wonderful opportunities to watch and learn about alpine ecology, it also can create problems.

In recent years, residents have observed the periodic arrival of butterfly collectors to their tiny town. Local concerns about the sustainability of alpine butterfly populations prompted research studies and heightened awareness about collection permit requirements.

Hobbyist collectors who take a few mature butterflies are unlikely to damage local populations. O'Donoghue says it's the prospect of commercial collectors who might gather up an entire colony of larvae to hatch out perfect specimens for sale that is of greater concern.

"But habitat destruction is generally considered a bigger threat than the collection of butterflies," he adds.

O'Donoghue says that all butterfly collectors -- whether hobbyist, commercial or scientist -- need to apply for a Scientists and Explorers Permit.

"They need to pre-apply and the process can take a few months, so we've connected with lepidopterist clubs and websites to make sure that collectors are aware of Yukon's permitting requirements before they make their trip here."

Local awareness of the butterflies is also very high. "Residents were becoming very suspicious when some of these collectors would pass through town. Butterfly collectors are a very secretive bunch, and locals didn't like the secrecy around what they were up to," says O'Donoghue.

For local residents, their vision has also been to develop ways to interpret butterfly ecology and their alpine habitat for visitors to the Silver Trail. The newly opened Keno City Alpine Interpretive Centre showcases interpretive displays and information about the peaks surrounding the community. Tourists and hikers can learn about birds, butterflies, wildflowers and mammals like pikas, marmots and bears that live in the area.

"July is the best time to view butterflies on the hills around Keno," says O'Donoghue. But these hardy northern butterflies are still sensitive to weather conditions, so timing a visit to Keno Hill for a warm, sunny day is wise.

"They aren't happy in strong winds, and they don't like cold, wet days," he says. "It's amazing to watch when the sun comes out-all of a sudden the butterflies start flitting about."