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Why are there earthworms in our eavestroughs?

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We found a lot of earthworms in our cottage roof eavestroughs. How would they get in there? It seems unlikely that they climbed up from the ground.
—Jack Hope, Go Home Lake, Ont.

You’re right: It is unlikely that the worms crawled up from the ground. It’s not impossible, however. Some species do climb vertical surfaces, such as trees. But the more probable scenario? The worms (or, at least one worm, since some varieties can reproduce solo) were deposited on your roof, or directly into your eavestroughs, by a bird. If the conditions are conducive to reproduction—optimal temperature, moisture, and soil pH; possibly some mood lighting and a glass of wine or two—you’ll eventually have your own bustling worm habitat.

“Earthworms do not travel very far in their lifetimes,” explains John Reynolds, an earthworm researcher who runs the Oligochaetology Laboratory in Kitchener and is the editor of the journal Megadrilogica. “If they find a suitable habitat, they stay there as long as there’s sufficient food and moisture.”

Erin Cameron, of the Alberta Worm Invasion Project at the University of Alberta, agrees. “A gutter with some debris in it would be a great habitat for earthworms that live in leaf litter.”

In fact, if even one egg (called a “cocoon”) hitched a ride into your eavestrough earthworm paradise—because it was stuck to a bird’s feathers, say, or attached to a wind-blown leaf—that could be enough to jump-start an entire population.