There are some birds who are known mimics; mocking birds, if you will. The Gray Catbird is such a bird. Generally, it mews. Mewing is perhaps it's first or native call? I spent an entire morning in my yard trying to find the crying kitten...before I discovered I was hearing a Gray Catbird. Unless he is singing, the Catbird is difficult to find...preferring to skulk about in deep cover. When I finally saw one, I was amazed at how pretty they are; almost completely gray, with a dark cap and pretty red 'panties'. Well, that's how I think of them.
The following clip, from BirdChick (AKA Disapproving Rabbits) shows a young bird, still practicing his mewing.
Here is another bird, a Northern Mockingbird this time, which has his song a bit more polished:
But, why do they mimic? What prompts a Catbird or Mockingbird to imitate all these sounds? Some even learn car alarms, cell-phone rings, police sirens. Why do they do this? Cornell's Laboratory of Ornithology has the answer in this stunning clip which takes us through the songbird's song...it even does frogs!