Embark with conservation ecologist Chris Morgan on a great challenge: to find and film the Siberian tiger.

婉转，清丽，高亢，鸟儿在枝头欢唱。世界自然纪录片之父爱登堡老爵爷讲述鸟类鸣叫对于种群的意义。
David Attenborough chooses seven of the most remarkable animal songs found in nature and explores the significance of these songs in the lives of their species.

剧情介绍:
本节目的主角是母虎(Tiger Queen)玛琪莉(Machli)和它的三只幼虎，玛琪莉霸占湖边的地盘已经11年。当幼虎逐渐长大，面临的危险也越来越多，少了母亲的陪伴，它们得冒险进入荒野去寻找自己的地盘。其中一只把目标对准湖边，争斗随即展开；一只只的老虎都打败仗，唯一屹立不倒的是母虎玛琪莉。在这场生存的战斗中，女儿会挑战母亲吗？本节目高清拍摄，揭露印度老虎的世界，展现老虎的雄伟、秘密和生存之战。

Jungle tigers are turning into man-eaters in the exotic island of Sumatra. Now a maverick millionaire is catching the killers and releasing them on his land. Is this madness, or could it save them from extinction?

David Attenborough has a passion for birds' eggs. These remarkable structures nurture new life, protecting it from the outside world at the same time as allowing it to breathe. They are strong enough to withstand the full weight of an incubating parent and weak enough to allow a chick to break free.
But how is an egg made? Why are they the shape they are? And perhaps most importantly, why lay an egg at all? Piece by piece, from creation to hatching, David reveals the wonder behind these miracles of nature.