The male red-winged blackbird has a bright-red patch on its shoulder. This adaptation increases its chances of mating with the female blackbird. Some of the birds underwent mutation, and their offspring didn't have the red-colored patch.

The correct answer is - it increases the variety but it is not the only attribute that allows mating in red-winged blackbirds so mating will be less but still occur.

Explanation:

The red patch in male red-winged blackbird help in increasing the chances of mating but it is not the only characteristic or way they impress the females but there are many ways.

Males give their most of mating time in humming on a higher perch in their territories. They make a nest for both males and females to protect from threats and intruders.

to this answer it would be edge enhancement

answer an inhibitory neurotransmitter in the brain;