#Magically created animals aren’t real animals.

In an interview, J.K. Rowling explains that she’d decided conjured objects wouldn’t last for very long. 

>Q: It seems that the wizards and witches at Hogwarts are able to conjure up many things, such as food for the feasts, chairs and sleeping bags. . .if this is so, why does the wizarding world need money? What are the limitations on the material objects you can conjure up? It seems unnecessary that the Weasleys would be in such need of money. . . (Jan Campbell)

>A: Very good question (well done, Jan!!). There is legislation about what you can conjure and what you can't. Something that you conjure out of thin air will not last. This is a rule I set down for myself early on. I love these logical questions! <br><sub><sup>*- South West News Service Interview with J.K. Rowling (July 8th, 2000)*</sub></sup>

Therefore, wizards wouldn’t be able to conjure new Snidgets because they’d they’d disappear soon enough again. Wizards also don’t seem to be able to create life - no animals that were originally an object that was Transfigured into an animal are shown lasting long-term.