How big will he get?

[Alicia]

Is 3ft normal for a male?

I don't think it is, no. I'm with you, I also think it is more like 4 - 4.5 for an adult. While I don't have it in front of me, average sizes of male BPs are briefly covered in the Barkers' book -- the average lengths are close to the same. Also in the passage, it notes that the collected females had recently laid, and so weighed less at the time than their male counterparts. Females, of course, likely have the greatest maximum size.