Graureiher

The german taxon name Schreitvogel is Ciconiiformes in francais et anglais, easily traced to cigogne and ciconia (like an active artificial insemination agency). Das Verb schreiten means a particular way of walking, especially for birds. Il manque a particular French mot (marcher), but the English stride is fairly close. This nice foto is the double: deux Schreitvögel schreiten (from suedpool.de):

voir artwork similaire pour deux humains,(Igor Ustinov, seen in Zürich, kultussen.blogspot.com)

mais ne plient les genoux d'oiseaux dans l'autre sens que les genoux de l'homme ?

From Mark David’s site (http://www.mdavid.com.au/birds/birdknees.shtml):

birds’ knees bend the same way as human knees. The reason why it’s confusing is because we don’t see their knees. Instead, that joint in a bird’s leg which kind of looks like a knee (except it bends forwards) would more accurately be represented by our human ankles.

Giacomettis L'Homme qui marche I (schreitender Mann) hat keine Knie,  his legs are gerade, il ne pouvait pas marcher. 

This 1961 Plastik has been sold at Sotheby’s for 74 million Euros. Andere Schreitende der Kunstgeschichte have knees, so the classical Athena :

Rodin :

Picasso :

But closest de la promenade de l'oiseau is Rodshenko :

and Edgar Augustin:

Der Schritt des Berliner Graureihers has been observed at the Friedrichsgracht Berlin, wo er auf der Grünstraßenbrücke im Schneetreiben promenierte :

Der Druck uses a Hintergrund gris followed by a contour plate. 

Un gradient gris has aussi been used, oder ein dunkleres Grau am Reiher, enfin, le bec et l'oeil sont coulorié.  

A classic b&w version :

Est-ce possible d'identifier le sexe du héron ? This seems quite schwierig, mais if you have a couple, the bill of the male is longer.