Hi Debbie,
You've received some wonderful suggestions. Usually, when I'm coloring something that is white, I use a little gray inside the image along the lines, and I might add a backwash outside the image. Probably easier to see what I'm talking about than read the words....I don't have chickens as an example for you, but I did find this rabbit in my gallery, that illustrates what I'm trying to say....
Rabbit with a Palette by LittleSeaOtter at Splitcoaststampers
Best thing to do...just play around with these different suggestions. You'll find one that looks best to you. Good luck!