The tiny hunter

Inspired by the joy of biodiversity, a pioneering scientist discovered the rapids clubtail along the rivers of southern Ontario. Today, the species is the first of Edmund Murton Walker’s beloved dragonflies to be declared endangered.

By Peter Christie
Dragonfly close-up

Credit: Blair Nikula

On May 29, 1926, Edmund Murton Walker, a quiet professor with a trim beard and a (usually) dignified manner, lunged net-first into Toronto’s Credit River to bring ashore a mystery. For Walker, this was a typical activity for a late-spring Saturday; he was well known for transforming even a casual outing into a wild, energetic hunt for insects. The animal he netted – a pale dragonfly nymph – was puzzlingly unfamiliar, and solving the riddle took time: Walker was obliged to raise his captive in the laboratory until it finally crawled from its larval armour.

“On June 7th an adult male Gomphus emerged and was killed on the 10th when the colours were mature,” Walker wrote in the journal Canadian Entomologist. “This specimen proved to be G. quadricolor, a rare species hitherto unknown from Canada.”

Gomphus quadricolor is commonly known as the rapids clubtail, and finding the medium-sized, boldly marked dragonfly was one of many firsts for Walker. The long-time University of Toronto zoology professor and former assistant director at the Royal Ontario Museum continued to discover new or regionally unknown insects, especially dragonflies, almost until his death in 1969. His three-volume

Odonata of Canada and Alaska set a standard for insect science in Canada and, for more than half a century, no one in this country – perhaps no one on the continent – knew dragonflies and damselflies better than Walker did.

Last September, the rapids clubtail became the first of Walker’s beloved dragonflies to be declared an endangered species in Ontario.

Dragonflies in trouble

 

The rapids clubtail was the first Ontario dragonfly to be listed as endangered, in 2009, but it may not be alone on the list for long. Almost a quarter of the province’s 171 dragonfly and damselfly species exist in fewer than 20 known locations across Ontario or are otherwise in serious trouble, according to the Natural Heritage Information Centre of the Ministry of Natural Resources (MNR).

“For some of these species, we just don’t know … whether their populations are declining,” says MNR zoologist

Colin Jones. That is because little is known about many of these insects and few have been studied carefully.

The pygmy snaketail, for example, is so rare that the animal was only recently discovered in Ontario. An announcement of the species’ official designation in the province is expected soon, says Jones, as the Committee on the Status of Species at Risk in Ontario completed its status review in late 2009. The pygmy snaketail was declared a national species of “special concern” two years ago.

The riverine clubtail may also soon be declared an Ontario species at risk. The provincial population of this dragonfly (also found in Manitoba and Quebec) lives in just two places on the fast-flowing streams along the north shore of Lake Erie. It is, according to the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), a “high-priority” animal, and biologists have just begun an assessment of its status in Canada. The dragonfly’s habitat in Ontario is under pressure from pollution, development and the diversion of water for irrigating nearby farms.

The provincially rare Laura’s clubtail was the subject of a COSEWIC status report completed in 2009, says Jones. The result of the review – an official assessment of its species-atrisk status in Canada – is expected in April 2010. (A species status designation in Ontario typically follows a COSEWIC assessment to avoid duplicating efforts.)

The spatterdock darner and the russet-tipped clubtail are other Ontario dragonflies on COSEWIC’s list of species in need of a status assessment (although they are a lower priority than the riverine clubtail). Jones adds that he is preparing the COSEWIC status document for the Hine’s emerald – a scarce dragonfly that was detected in the province for the first time in 2007.

All this sounds like bad news for dragonflies and their aficionados, but more importantly, says Jones, these troubled insect populations may be painting a grim picture of Ontario’s general ecological health. “Usually, the reasons why something is gone are reasons we should really be concerned about,” he says.

 

Peter Christie

According to biologists, the rapids clubtail population on the Credit River – where Walker caught his mystery nymph – has been wiped out. Of the other Ontario populations subsequently discovered along southern Ontario’s Humber, Thames and Mississippi rivers (in 1939, 1989 and 2001, respectively), only three sites (one on the Humber and two proximate spots along the Mississippi) still sustain rapids clubtails.

“This was never a common dragonfly. Its populations are isolated throughout its range, and Canada is at the northern fringe,” says Allan Harris, co-author of a 2008 status report on the species for the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). “But there certainly is evidence of decline.”

Dragonflies and damselflies are among Ontario’s most charismatic creatures. These sleek hunters of midges, mosquitoes and other airborne bugs dart and dive over fields and ponds with a mesmerizing aerial genius. Most of the 171 species in the province (a small number compared to that of other orders of insects) are strikingly coloured, and many are large enough to spot as they glance by a gliding canoe or patrol a summer lane.

Larval dragonflies and damselflies live in the water – often for years – and this biological trait makes them useful as indicators of ecological health and water quality. For this reason, the news of the rapids clubtail’s decline is especially disturbing. While the numbers of other insects are often estimated to be in the millions or billions, Ontario’s rapids clubtail dragonflies can be counted in mere hundreds. A 2005 survey of historic and suitable sites for the animal estimated that fewer than 320 individuals (adults and nymphs) remained north of the U.S. border.

Although dragonfly numbers are notoriously uncertain, the Canadian population of the rapids clubtail (confined solely to this province) is clearly in peril: a number so small in so few locations brings to mind the flickering before a candle goes out. In 2008 – the year of Harris’s report – COSEWIC declared the dragonfly nationally endangered. Ontario followed suit a year later.

“It’s vulnerable,” says Harris. “There’s no question.”

Concern for vulnerable species was not something Walker discussed much in his writing; in many ways, conservation biology came into fashion after his time. Instead, he wrote about the thrill of discovery and, by implication, the joy of biological diversity. At a time when most biologists were, as he said, “exclusively laboratory men,” Walker preferred the outdoors: forests and streams were places for a chance meeting with something remarkable and new. “I had an inborn love of animals,” he once recalled, “both as fellow creatures and as objects of interest and attraction.”

From the beginning, Walker’s ardour was encouraged by his gift for identifying plants and wildlife. He became a painter and an illustrator, and his careful drawings complemented the articles and books he wrote. He also developed a lively habit of imitating insect sounds and sometimes flapping his arms during his university lectures to mimic insect behaviours. “He was a delightful person,” says Conrad Heidenreich, the zoologist’s grandson. “He had perfect pitch and would chirp to attract insects. He delighted in making one land on his arm.”

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