Hi,
I think the label is a genuine label, so the bird was made in the Seguso factory. However, almost certainly not by Archimede Seguso himself as it is a production piece. My sense is that the signature is a later addition. I don’t think that it makes much difference to its value, though. In many glassworks birds like this are made by the less experienced workers. They are nice pieces (i’ve bought more than a few), but not worth a huge amount.
Hope this helps.