Is it Escadrille 471?

This is the aircraft. Escadrille 471 was a French unit an existed from 10 May 1918, and dissolved on 18 July 1918. Commanded by a French officer Lt. Sanche de Gramont but manned by American pilots. "The black buffaloes" certainly refers to Escadrille N. 471. The origin of the name was the fact that "one" of the unit insignias was a black silhouette of an American buffalo or bison on a yellow oval with black outline. The buffalo was selected as a quintessential symbol of the USA, and was based on the image on the buffalo nickel or 5 cent piece. This was the third escadrille insignia selected - the first two were variations of a triangular pennant colored like the American flag. The unit flew Nieuport 27 and SPAD VII types.

This aircraft was flown by Lt. Lawrence Cauffman and the unit's duties were the defence of Paris. It was also called the 1st Reserve Aero.

The unit was thrown into the defense of Paris and the pilots busied themselves running interdiction and strafing missions in the area of Coulommiers which is where 1st Pursuit Group was operating. And then after 7/23 or thereabouts a good number of them including Avery were sent to 1st PG.

I had a nice time with my son working on identifying the aircraft and trying to find a matching insignia. A late night image search of the Nieuport 27 with the AEF turned up an image of the buffalo at wings palette, with a broken Russian translation.