Recently bought this interesting glass bird. It appears in Desna catalogues as 'Sparrow II' No. 27879 00 050 (see http://www.desna-glass.cz/pages/en/katalogen.html
) and was apparently originally produced by C. Schlevogt, Gablonz.
This example seems a little unusual as it is in a blue opaque glass, not the marbled Lapis glass typically associated with Schlevogt, but a pale blue 'milk' type glass, of a colour you might more readily associate with Sowerby or Portieux.
I am wondering whether this is older or newer production, or possibly a copy by somebody else? The mold quality is very good and the finishing a little different to the Desna examples I've seen but the glass does have some black inclusions/surface deposits from manufacture. The foot is ground smooth but not brightly polished. The mould seams on the body have been heat finished with a touch of wheel polishing where they meet at the head. the ends of the tail have also been wheel ground. Height is approx. 6 cm, length 12.5 cm.
Frank, if it's any use for the zoo, I can send you the high resolution pics.