If there are no traces of any career of Jean Loesebergh, there's a reason why. Raymond Smeets,
the son of Fernand Faniard, mentions Loesebergh in his excellent long text about the
records of his father; since that text is in French and hence
probably not comprehensible for everyone, I translate the snippet on Loesebergh:
One of the collectors that Smeets got to know as a consequence of his efforts to get his father's private recordings back was
Armand Ransonnet. At Ransonnet's home in Herstal, at some time around 1990, we met a semi-professional tenor, in his 70s but
still endowed with a commanding, beautiful voice: Jean Loesebergh, who would later send me a curious recording where he sang the
famous aria from Trovatore, "Di quella pira", accompanied by the birds of his aviary.
The above sound files, however, prove that he also sang for human, not just for avian audiences.