I created this stylized illustration of a sparrow with a black ballpoint pen.

Here's my preliminary sketch (pencil on paper). 

Work-in-progress! I draw patterns with my ballpoint pen (on top of my sketch -- i'll erase it later); I chose a different type of pattern for the wing, to make it stand out. I also draw darker patterns for the legs and leave a blank space for the eye. 

Aaaand here's the illustration after i got rid of the sketch underneath and scanned it.