It’s summer, and our solar-powered planet is bustling with animals on the move. Snow geese are breeding in the warming Arctic tundra, and tadpoles in Vancouver are trying to grow into toads; whale sharks are gathering to feed in the Persian Gulf, and in Europe, the honeybees are hard at work building new hives. In Alaska, thousands of sockeye salmon have flushed bright red to make their journey upstream to spawn, an annual event that freshwater seals and grizzly bears depend on to fatten up for winter. With virtually no sea ice remaining in the Arctic, polar bears now spend most of their days swimming, and a young cub who struggles to keep up with his mother may be left behind. But the most treacherous journey of all can be found on the plains of the Serengeti, where wildebeest and zebras must cross the “River of Death” to find fresh lands on which to graze. Many of them will drown in the stampede to make it through the water – if lions and giant crocodiles don’t eat them first.
