All animals with feathers are in the Class called birds or Aves just like all the warm-blooded vertebrate animals with hair and females that produce milk are in the Class called Mammalia. Other Classes include Amphibians, Reptiles, and Pisces. Each animal within their class is then further defined by Orders, Families, Genera, and Species.
All dog breeds are mammals and belong to the species Canis lupus familiaris. Domesticated cats are also mammals that belong to the species Felis catus. While both four legged mammals, they cannot mate and produce offspring. There are about 10,000 species of birds and the difference between the House Wren and the House Finch is similar to that between a dog and a cat.
Birds have an innate ability to recognize their own species and look for mates based on their song, color of plumage, and behavior or distinctive courtship displays. Only bird species related closely can interbreed, producing hybrids. One example is the Baltimore Oriole which can hybridize with the Bullock's Oriole where their ranges overlap in the Great Plains.
The last picture you sent me is of a Chipping Sparrow. Chipping Sparrows, like the House Wrens and Finches are well adapted to the presence of people and don’t mind if you are nearby. They live and nest in a very wide variety of habitats, including the suburbs.
How do you become a birdwatcher? http://bit.ly/rquunU
Best field guide for Michigan birds http://bit.ly/vPOMx1
What are the Best Binoculars: How to Choose Optics http://bit.ly/vZW26j
Most common winter birds in Michigan http://bit.ly/vUZynL