Rook, watching the Great Convocation from above

"Large groups constantly breaking up and reforming, as if in some huge dance that every banderbear seems to instinctively understand... And the chanting - incredible, booming, resonant..."
Rook Barkwater, in his treatise-log

An Eyewitness Account of the Mythical Great Convocation of Banderbears was a treatise Rook Barkwater worked on between 84 and 86 ᴇ.ʏ. It contained a detailed analysis of banderbears' lives and their language, as well as an account of their legendary Great Convocation.

Rook started by searching for a banderbear to observe. He looked for tell-tale signs like their woven nests, fruit newly picked from trees or their heavy footprints. In his first three months he only heard banderbears' calls three times. Several times, he came across regularly visited spots, such as a lufwood tree used as a scratching post, however, he still wasn't able to find a banderbear.

After three months, he found a young, female banderbear at a spring, where he gained her trust. He made detailed notes of her behaviour in his treatise-log. He spent many weeks with Wumeru, learning about the lives of banderbears. He was able to get a much more accurate idea of their lives than Varis Lodd in her treatise A Study of Banderbears in Their Natural Habitat, because she had to rely on observing from a distance.

Eventually, Wumeru recieved the call to attend the Great Convocation, so she ran off and attempted to stop Rook from following her. He disobeyed her, and eventually discovered the gathering in a giant ravine.

It is unknown as to whether he ever completed his barkscroll between the end of The Last of the Sky Pirates and the beginning of Vox.