Art of training plants into different shapes of birds, domes, animals, umbrellas etc is known as

The art of training plants into different shapes of birds, domes, animals, umbrellas etc. is known as Topiary.
It is the horticultural practice of training perennial plants by clipping the foliage and twigs of trees, shrubs and subshrubs to develop and maintain clearly defined shapes, whether geometric or fanciful.
The plants used in the topiary are evergreen, mostly woody, have small leaves or needles, produce dense foliage, and have compact and/or columnar growth habits. The plant should be amenable to repeated pruning and also flexible with more vegetative growth.