When you say bird-travelogues or bird memoirs I assume you mean something in the style of Kingbird's Highways or The Peregrine ?
In which case, I don't think it really exists in French...Maybe Les tribulations d'un chercheur d'oiseaux by Philippe J.Dubois would fit this description ? I haven't read it but it seems like it's more of a collection of birding trip anecdotes...The recently published Eloge des oiseaux de passage by Jean-Noel Rieffel seems similar too.
Books by Jacques Delamain (Pourquoi les oiseaux chantent ?, Portraits d'oiseaux...) are beautifully written and a nice example of French "nature writing". In Pourquoi les oiseaux chantent ? is included (at least in the edition in which I read) a journal of the author during the first world war during which he used birds as a way to escape the horror of the situation.
Books by Paul GĂ©roudet (Swiss ornithologist but he wrote in French) are more like monographs of (most) European species. A mine of information but what made those books famous is that almost all species account start with a short description of an observation of this species in the field in a very evocative and poetic style.
I don't have the books next to me right now but here is an example of what he writes about the Robin (from his Wikipedia page) :
« Novembre chasse les feuilles desséchées, les derniers vols de freux et de choucas rament vers le midi, au-dessus des brumes bleuâtres des bas-fonds. Dans le bois, les clameurs aigres des geais percent le silence. Asseyons-nous en lisière d’une coupe, puisque les troncs abattus gisent encore au bord du chemin. Quelques mésanges vagabondes ont passé, et soudain, sur une souche, un petit oiseau surgit, gris-brun, avec un grand plastron orangé et deux grands yeux noirs qui nous regardent. Le rouge-gorge, toujours curieux, est-il attiré par le bruit des pas brisant les branches mortes ? Attendrait-il quelque chose ? De ci, de là , il sautille à distance, puis l’inspection est terminée et il regarde le fourré où éclatent aussitôt quelques petits cris secs. »
I hope this is of interest to you !