Well that clearly illustrates what an enormous effort it is for a Kiwi to produce an egg. 1/3 of their body weight, if I remember correctly.
about 15-20% of their body weight (or can be up to 26% in the little spotted kiwi because its a smaller bird). There's a famous X-ray photo of a brown kiwi taken a day before laying which illustrates it even better than this. Our Space
Scandal Revealed! Zookeepers stop feeding collection and pocket the seed money! Animals emaciated. Horrible photos. Movie at 11