Various studies have concluded that song overlapping, the phenomenon where one bird begins a song while another of its species is singing, is a signal of aggression. █████ ███████ ███ █████ ██████ ██ █████████████████ ██████ █████ ████ ██ ██████ ███████████ █████ ███ ██████ ██ █ ██████ █████ ██ ███ ██████ ███████ ██ ███ ████████ ███ ███████████████ ██ ██████████████ ██ ███████████ ██ █ ████████ ██ █████████ ███████████ ██████████ ████████
Studies have concluded that song overlapping is a signal of aggression. These studies are based solely on receiver-response tests, which derive conclusions about behavior based on how others respond to it. Any response, including no response, can be interpreted as a reaction to aggression.
The studies are inconclusive in showing that song overlapping is a signal of aggression.
Which one of the following ████ █████████ █████████ ███ █████████
birds do not ███████ ██ █ ███████████ ██████ ██ ███████ ██ ██████████
receiver-response tests can ███████ ██ ███████ ████ ████ ████████
song overlapping is ██████ ███ █ ██████ ██ ██████████
song overlapping has ██ █████████████ ████████
the conclusion of █████ ███████ ██ ████████████