Squawk

Squawk was a living metal, robotic bird from Pheros, who served Baltazar as a spy. His father was Caw, who Squawk later mourned. Squawk was disguised as a small brooch, given to Martha Jones by Caw. When the Doctor's TARDIS was hijacked by the space pirate Baltazar, The Doctor waited until Squawk had grown big enough to ride upon, and traveled to the Infinite to rescue Martha. After the Doctor defeated Baltazar, Squawk took him to the prison planet Volag-Noc, where he belonged. (DW: The Infinite Quest)