Why do bird eggs need warmth from the parent to develop, while fish, amphibians etc don’t?

Question

My head can’t get around the idea of why they wouldn’t just grow but slower because of a lower rate of reaction!!

In: 3

Answer 1

Birds are warm blooded like mammals, and their body chemistry only works in a narrow temperature range.

This gives them the incredibly powerful metabolisms required for all that flying they do in all sorts of weather, but also requires a lot of effort to keep themselves and their young in that temperature band.

Fish, reptiles, and amphibians have metabolic chemistry that works over a broad range of temperatures, saving a lot of energy but putting them at the mercy of a cloudy day.