I believe the technique for this style of glass is 'Incalmo' where block colours are fused together.
The pieces must be exactly the same size, consequently, this is a technically complex technique, demanding great precision and, with this weight of glass, is also physically demanding.
So if it is Incalmo, it is likely to be from a specialist glass studio, with skilled glass artists, and my thoughts were, on first seeing this lovely bird /sculpture, that it could possibly be Venini or Fratelli Toso from Murano.