So, when Fulgour mentions the Bennu bird, is mostly referring to the idea of a bird of “eternity”, a symbol of resurrection, rebirth, and revitalization – the phoenix also mentioned, and which we inherited from the Greek, inclusively as a Christian image. Its connection to Venus, the Morning Star, and to a sacred tree, is particularly appealing here.
We can approach this kind of imagery in several ways; the first level of exegesis takes us to the broader, even “universal” meaning of “a bird”. It is, I believe, very important to get acquainted with this level of interpretation, if one wishes to have some real knowledge of the Arcane. And a certain degree of truth will certainly be found.
Then, we could discuss which bird is this. Is it black or white? Is it a crow, a dove, a rooster? And, if trying to pursue an historical thread, is it an evocation of the Bennu bird, such as the phoenix? A mythic “primordial” bird is to be found in many cultures, as is the case of the Rukh of Arab mythology, or the Kirni that lives in Yggdrasil, the sacred tree from Nordic mythology (and many more). They are all associated to a tree, a representation of the axis of the world, and also a symbol of life in itself. They are also associated, of course, to a primordial egg, relating once more to Life, to birth (and rebirth).
To me, it is particularly important to keep in mind the main characteristics of a bird: it flies, it sings, it lays eggs.
Flying is all about finding a path to Heaven, and sublimation (sublimation of the body and matter in general, purification of the soul, elevation of the self…).
Singing is about delivering a spiritual message: listen to the crystalline, angelic voice that carries it. It demands from your ears - and this reminds me the French words oie (goose - again on the Language of the Birds) and oie (to listen, or hear). It demands from your deeper understanding.
Laying eggs is about Life, birth and rebirth, and the primordial mystery of the creation of the Universe.