This video from the USA says about itself:
A Master of Song: Northern Mockingbird
11 March 2015
A master of mimicry lets loose. You never know what’ll come out of this bird’s beak next.
What’s happening: With hundreds of songs in his repertoire and the stamina to sing for hours on end, the male Northern Mockingbird (Mimus polyglottos) specializes in vocal excess. A masterful mimic, he mixes a variety of songs borrowed from other species with his own material to defend his territory. His capacity to improvise is so extensive that he’ll sing many of his song types only once a season. The overall effect is that listeners never quite know what will come out of his beak next—and for mockingbirds, it’s variety that counts.
Videographer: Eric Liner. This video is archived at the Cornell Lab’s Macaulay Library, ML466291.
From the Cornell Lab of Ornithology in the USA:
Mockingbirds Can Learn Hundreds of Songs, but There’s a Limit
Northern Mockingbirds can learn hundreds of sounds that they weave into songs, even replicating sounds from other birds and from noises in the environment such as car alarms and squeaky gates. Do males show off their greater age or experience by singing more songs? Not according to a study that tracked 15 birds as they aged. Read the story in Living Bird.