Open this photo in gallery Western toads are seen near Whistler B.C. in this undated handout photo. HO/The Canadian Press

An annual migration involving tens of thousands of creatures is under way in Whistler, B.C., but observers could miss it if they don’t look down.

Up to 40,000 tiny western toadlets are climbing out of Whistler’s Lost Lake where they hatched as tadpoles and are moving into the surrounding forest.

The dime-sized toads, which are native to British Columbia and listed as a species of special concern, grow to full size in wooded areas before returning to the lake to breed.

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The Resort Municipality of Whistler says western toads are an important part of the Lost Lake environment because the tadpoles feed on residue in the lake, keeping the water clean.

But the little amphibians are particularly vulnerable during the toadlet stage as they cross beaches, trails, lawns and busy roads in their journey.

The Whistler website says the road to Lost Lake, as well as the beach and lawn are still open, but closures are possible at the height of the migration when as many as 1,800 tiny toads can hop over roads and paths every hour.

A statement on the website says environmental technicians and volunteers monitor the migration, while temporary fences, signs and boardwalks have been installed to protect the toadlets from getting crushed.

The migration will continue for the next three or four weeks. People are encouraged to observe, but are urged to leave pets at home.

“Dogs are not allowed on the beach area, as they may trample tadpoles and can become sick from ingesting or licking amphibians,” the statement says.

Whistler’s migration has been monitored since 2005 because western toads are very sensitive to environmental changes and the municipality says the amphibians offer an insight into the health of the area’s entire ecosystem.

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