Self-study
Birds startled by potential predators generally try to take cover in nearby vegetation. ███ ████ █████ ████ ████ ██ ████ ███████ ██████ ██ ████████ ███████ ███ ██████ █████ ████ █████████ ████ ███ ████ ████ ███ ██████████ ██ ███ ███████ ███ ████ ███ ███████████ ██ ██████ ███████
"Surprising" Phenomenon
Birds usually hide in vegetation when startled, but tend to flee vegetation when startled in suburban gardens.
Objective
A hypothesis explaining this behavior must imply a difference between startled birds in general and birds startled at feeders in suburban gardens. This difference must explain why birds in suburban gardens seem to buck the trend by fleeing vegetation and colliding with windows.
3.
Which one of the following, ██ █████ ████ █████ ██ ███████ ███ █████████ ████████ ██ ███ █████ ████ ███ ████ ████████████
a
Predator attacks are ██ ██████ ██ █████ ██ ████ ███████ ██████████ ██ █████ ██████████ ██ ████ ███ ██ ███████ ██████████ ██ ██████ ██ ██ ███████████
This eliminates an irrelevant distinction. The author states or implies no difference between feeders surrounded by dense vegetation and those surrounded by little to no vegetation, nor suggests to which category suburban garden feeders belong.
b
The bird feeders ██ ████ ████████ ███████ ███ ██████ ██ █ ████████████ ████████ ████ ███ ███████
This deepens the mystery. If the birds are long distances from the windows when startled, their collision with them seems less coincidental—yet no more clear.
c
Large birds are ██ ██████ ██ █████ █████ ██ ███ ████ ████████████
This is irrelevant information. The author makes no distinction between large and small birds, so their similarity in this respect does nothing to explain the birds’ behavior.
d
Most of the █████ ████████ █████ ███████ ██ ████ ███████ ██████ ██ ████████ ███████ ███ ████████ ██ ████ ██████ ██████ ████ ██ ██████████
This is an irrelevant distinction. There is no suggestion that birds startled by noises are less likely to seek vegetation than birds startled by predators.
e
The windowpanes of ████ ██████ ███████ ███████ ███████████ ███████████
This explains the tendency of birds at suburban feeders to collide with windows. The birds mistake the windowpanes for vegetation, colliding with them accidentally.