This video from the USA says about itself:
25 March 2016
Male Red-Winged Blackbird‘s loud song and territorial display with big bright red epaulets or shoulder pads puffed up to their maximum extent in a showy display to intimidate other males. This bird has developed a very nice whistle flourish to his song finish that sticks out among the others. You can hear other nearby males singing.
Although a fairly common bird of the marshes and fields it is a very striking songbird and their song a relaxing reassurance that warm weather is on the way and to me always a reminder of my childhood in the country!