Yellowhammer: Male & female

In the Yellowhammer the sexes differ clearly.

Male: brilliant yellow head and yellow underparts, rusty-brown back and breast sides; the yellow is at its strongest in spring and early summer.
Female: paler and more heavily streaked with less yellow, with clearer dark streaking on the head and breast.
In common: both sexes have the warm rusty-brown rump, a reliable feature in all plumages that shows clearly in flight.
Juvenile: resembles the female but is even duller and almost entirely lacks yellow, which can make young Yellowhammers tricky to identify in autumn.

More about the Yellowhammer