[nordsieck]

> It seems like these animals evolutionary strategy is akin to that of the cuckoo bird.

Animals have a dual strategy.

They can be part of the family or they can be a working animal.

> Is there a direct connection between falling birth rates and treating animals as if they were beloved children?

I could see treating animals as children being caused by falling birth rates. The opposite seems unlikely, since people have kept pets for a very long time.