An army of thousands of frogs and toads traveling to their summer breeding grounds have forced the closure of a busy road in Estonia's capital Tallinn.

The amphibians are normally transported by volunteers, who have moved 97,000 of them in previous years, including 2,000 last year alone.

But this year, COVID-19 measures have meant they've traveled alone and now authorities have taken action to ensure they aren't hit by passing traffic on one of the city's busiest roads.

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"The frogs were here before the road," said Kristel Saarm, an Estonian National Fund volunteer. "Now the ponds where they breed are on one side of the road and their wintering place is on the other. So they are forced to cross."

The warm surface of the road can make the amphibians sleepy and slow and up to 300 of them can get stuck at a time, leaving them vulnerable to cars.

Tallinn is considering building a tunnel under the road for the frogs and toads to cross or providing a pond on the side where they overwinter, said deputy head of Haabersti district Oleg Siljanov.