Dionne was a self-taught scientist and wrote several books on the natural history of Quebec, including the first field guide to the province's mammal fauna; he was a well-respected scholar and became a fellow of the American Ornithologists' Union.
His father was a cobbler and farmer but the couple attached considerable importance to education, and Charles-Eusèbe displayed a thirst for knowledge from a young age, which was first noticed by his aunt Philomène.
After he had completed his elementary study, Philomène was the one who paid so he could benefit from private classes, where he came across a natural history book, an incident he would delight in recount in his later years, even though he could not remember the title.
His predisposition was rapidly noticed and, having benefited from personal teaching sessions with Thomas-Étienne Hamel, he was promoted from cook to a position at Université Laval's (then administrated by the seminary) faculty of law.
He became friend with historian and librarian Charles-Honoré Laverdière, and acquired from him scholarly techniques and instinct, all the while developing his knowledge and becoming an admirer of Léon Abel Provancher.
Dionne subsequently remained the main taxidermist for the museum under Saint-Cyr's successors, and it was curator Victor-Alphonse Huard who would later suggest his candidacy to the Royal Society.
The perceptive and up-to-date (it used the American Ornithologists' Union classification), if short on overall information, ouvrage garnered good reviews from specialists such as Elliott Coues and Charles Foster Batchelder.
Future president of the Union Jonathan Dwight noticed a very recent and subtle publication of his being taken into account and visited Dionne in 1891 to check on it.
This friendship and the one Dionne struck with Ruthven Deane in 1893 when he was delegated by Laval to Chicago for the opening of the Field Museum of Natural History were instrumental to his election that year as fellow of the AOU.
This has often been blamed on racism on the part of the primarily English-speaking scientific section (Huard at the time was the sole French-speaking member, Léon Abel Provancher and other scientists had been elected to the Academy of Arts and Humanities as writers to get around this problem), but a turn in recognition from the "learned amateurs" of the 19th century to the formal academics cannot be entirely discounted.
Dionne died of illness in Quebec City on 25 January 1925, a mere few days after Laval granted him an honorary Doctor of Science degree (he commented of it "They should have waited after my death.").
The precise amount of personal jealousy (Chamberlain was preparing his own Catalogue of Canadian Birds) and scientific concern (Dionne's work only truly covered Quebec, and used the soon-to-be obsolete classification of Coues) is difficult to assess.
Alongside figures like Léon Provancher and Marie-Victorin, Dionne was a driving force in making natural sciences, and particularly birds, of interest in a time when such research was not considered very important.
Dionne's taxidermy work was appreciated and widely distributed, and his observations are important in tracing trends in bird population evolutions over time, such as those of the passenger pigeon.