These are called Matryoshka Dolls, Nesting Dolls or Stacking Dolls. In work the artists used tempera with egg emulsion and fine polecat brushes. Very rich and bright paints are used. The birds are painted so vividly that looks like alive. The birds are painted very detailed and hundreds of individual brushstrokes make up the plumage. The tallest one is 4 1/2 ", the smallest - 1 1/4".