The photocell is pushed through the seam at the forehead. A dot of super glue holds the photocell to the animal. A piece of flexible wire (like rainbow wire with connectors cut off one end) can be soldered carefully to trimmed photocell leads. Protect the soldered ends with hot glue, Sugru, or other material.
Push the wire up through the beak. the other, stripped end is bent slightly and threaded into the servo horn.