 Confusion over the colouration of the Mascarene parrot has also been furthered by a plate by French engraver and naturalist François @-@ Nicolas Martinet in Buffon 's 1779 Histoire Naturelle Des Oiseaux , the first coloured illustration of this species . It shows the bird as brown with a purplish head , and the strength of these colours differs considerably between copies , a result of having been hand @-@ coloured by many different artists who worked under Martinet in his workshop . Across these copies , the body ranges from chestnut brown to greyish chocolate , the tail from light grey to blackish grey @-@ brown , and the head from bluish @-@ grey to dove @-@ grey . The plate also lacks two dark central tail feathers without white bases , a feature described by Brisson , and these features have been repeated by subsequent artists . Martinet 's illustration and Buffon 's description were perhaps based on the Paris specimen . 
