David Attenborough's Natural Curiosities (2013)

S4E3 Extreme Babies

The giant panda welcomes the tiniest newborn among mammals and must nurture and safeguard it for several months. In contrast, the kiwi lays one of the largest eggs in the avian realm, resulting in a highly advanced chick. This raises questions about why pandas don’t give birth to more mature and stronger offspring, while kiwis opt to produce a single egg that weighs a quarter of their body size, making it nearly too large to lay.