Last spring I posted an article containing many photos of the two colour “morphs” of the White-throated Sparow.
Chris Earley’s book: Sparrows and Finches of the Great Lakes Region and Eastern North America (Firefly Books) contains some other fascinating details.
The White-throated Sparrow is unique because it has a mating pattern like no other bird. There are two colour morphs, white-striped and tan-striped, and males and females can be either morph. The unique part is the fact that a pair is usually made of one of each colour morph. This apparently occurs because white-striped males are aggressive compared to tan-striped males.
Also, white-striped females sing, whereas tan-striped females do not. Because the white-striped females sing, the white-striped males are aggressive towards them and thus mate only with tan-striped females. This leaves the less-aggressive tan-striped males to mate with the white-striped females.