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> The specificities of various niche adaptations are wonderful: a bat has an
> advantage at night over birds, birds over bats in the day time.  Why?  At
> night, the bat's senses are superior to birds'.  In the day time,
> however, because they are more agile fliers, the birds aree supreme.
> This probably has to do with adaptations for weight.

Bats probably took to nocturnality because of predation from diurnal birds of
prey which, back in the Eocene, included early hawks and falcons as well as
predatory rollers. Modern islands devoid of birds have day-flying bats.

> The ratites are devoted to speed.

This is a true as 'the birds are devoted to flight': a generalisation with
several exceptions.

One thing that strikes me about all this egg-eating speculation is that eggs are
too rare a resource for any endotherm to utilise them as a full-time resource.
Only egg-eating snakes (_Dasypeltis_ and allies), very specialised and
ectothermic, eat eggs and nothing else. The many other tetrapods that eat eggs
do so opportunistically and cannot depend on them. Some skinks eat only seabird
eggs and chicks during the nesting season, but for the rest of the year subsist
on bugs. Foxes and some gulls will eat practically nothing but eider duck eggs
_while_ they are available. My point is that there are not seek-and-destroy
mammalian egg predators, nor have there ever been.

"With screams they rammed the sharp swords into their chests"