PLANET EARTH Seasonal Forests

The squirrels are busy mating. Good news for the hunter. A distracted squirrel, is a vulnerable squirrel. But, this time, the amorous couple is safe. There is a loner stocking his larder, who will be the easier target. Early summer, and great grey owl chicks are fledging（刚学会飞）. Adults can only raise young here in years when the seasonal vole crop is big enough to support them. The moment has arrived for their first flight.
Leaping from the world's tallest trees is not for the faint hearted. If you're going to fall here it's quite a good idea to do it in stages. The ground is no place for an owl. If he's to climb to the top of his class he'll need to persevere, so now, let's have another go. The American conifer seasonal forests may not be the richest in animal life but their trees are extraordinary.



This giant sequoia（红杉）, a relative of the redwood, is the largest living thing on Earth. Known as General Sherman, it's the weight of ten blue whales. Higher up in the nearby mountains, bristlecone pines（狐尾松）, the oldest organisms on the planet. Some have been here for five thousand years. They were alive before the pyramids were built and were already three thousand years old when Christ was born.