Beavers on the march

An aerial view of a stream that beavers have turned into a lake, disrupting ecosystems near Umiujaq. Drawn by a warming climate, Canada’s furry national symbol is colonising new territory and reshaping the world they find. — Renaud Philippe/The New York Times

UNTIL a few years ago, a small stream meandered down a long valley flanked by sheer ridges in Umiujaq, a subarctic village in northern Quebec.

The waterway had pretty much hewed to that course since the Earth’s crust rebounded after the last ice age.