After decades of speculation on what animals will be effected and what species will survive nuclear devistation, crows seem to be the only animal in the entire area that remain thriving and unchanged.

Roaches got bigger.
Rats got bigger and developed spunky mohawks.
Houseflies became troubling poisonous death from above.

Why are crows the one and only animal that remains completely intact when they are the most obvious choice for an intelligent deadly swarm?

Simple, not everything became mutated, at least not in obvious ways. Some of the Wasteland creatures were created Pre-War as weapons of war, deathclaws and mole rates to name two.

Also not all house flies became giant. There are still normal flies. Squirrels and iguanas are still normal but we still have not seen them.

dogs are the same ?

Crows might look normal but when u shoot them...well it's less than normal

Oh crap youre right...I forgot about the coyotes....though coyotes are usually not that agressive.

and crows are?

Dogs are mutated but are the least mutated creatures in the wasteland, they dont need to grow a extra arm to be condidered mutated

I've seen two headed crows, so some did mutate.