He has taught generations of students at Vienna, as is well known as a popularizer of scholarship for the broader Austrian public, particularly young people.

Birkhan received his PhD in 1962 under the supervision of Otto Höfler, with the dissertation Die Verwandlung in der Volkserzählung.

[1] Along with Otto Gschwantler, Peter Wiesinger and Erika Kartschoke and other future prominent scholars, Birkhan belonged to a circle of Höfler's favourite students who called themselves the Drachenrunde.

In January 1970, Birkhan habilitated in Ancient Germanistics with a thesis on the relationship between Celts and Germanic peoples in classical antiquity.

[1] In 1988, Birkhan established Niederlandistik [de] as a distinct course at Vienna, and subsequently secured the appointment of Herbert van Uffelen to teach this subject.

[1] For almost half a century, Birkhan has taught generations of students at Vienna, where he has become well known for his breath of knowledge and friendly personality.

[6] He has also dedicated himself towards making scholarship available to the broader public, notably appearing as a druid on the children's television program on the Österreichischer Rundfunk.

He has had two festschrift's published in his honor, Ir Sult Sprechen Willekomen (1998), which was edited by Christa Agnes Tuczay, and Kulturphilologie.

[1] Many of Birkhan's research projects have been carried out at the Austrian Academy of Sciences, such as the Lexikon der altgermanischen Namen [de] (supervised together with Hermann Reichert and Robert Nedoma), and Motif-Index of German Secular Narratives from the Beginning to 1400 (together with Christa Tuczay and others), which was published in seven volumes.