Nathan was really not much to draw but as luck would have it his mom was an amature bird enthusiest. There was a certain picture of flight patterns she took that always made him chuckle and reminded him of of her. He took that very picture to Howarts with him and maybe this was a picure he could draw if he tried it:

model picture:
Nathan drew Ms for the birds and did his best to make a picture of the same shape, the result was not pretty but it worked for the task at hand.
Nathans crude version of his picture: