With just a little practice and observation, you'll find that differences will jump out at you. Study the sillouettes in the picture and see how well you can identify a bird just by the combination of size and shape.
Sillouette Answers: 1. Great Horned Owl, 2. American Crow, 3. European Starlings, 4. White-breasted Nuthatch, 5. Cooper's Hawk, 6. Blue Jay, 7. American Goldfinch, 8. Carolina Wren, 9. Woodpecker, 10. Northern Cardinal, 11. Black-capped Chickadee, 12. Mourning Doves, 13. Fox Squirrel, 14. House Sparrows, 15. American Robin
So now that you know the shape of enough birds to participate in the Great Backyard Bird Count (GBBC) the third weekend in February, let me recommend a couple books:
One of my favorite features is a very handy quick find reference of all of the birds at the beginning of the book. It also lists Michigan birding groups and which local nature center or park will have a particular species of bird.
This is a very handy book to have around even if you don't plan on doing more than watching the birds at your feeder.
If you like photographs, I recommend Stan Tekiela Birds of Michigan book. There is also CD available if you want to hear their songs.
Both books will help when you need to name a bird for the GBBC.
Wild Birds Unlimited is a proud sponsor of the Great Backyard Bird Count. We encourage you to be part of this citizen scientist project that helps us learn more about the birds.