Answer:
The topic in:
Bird watchers must keep track of different types of birds. Often, birds are hidden in trees and bushes. Birders must count them without even seeing them. They identify the birds by their sounds.
is: Bird watchers' abilities
Step-by-step explanation:
There are two reasons for backing this answer. In the first place, all of the sentences build and present a profile of abilities a "bird keeper" has. The ext also describes how all of them have them establishing a generalization that means all "bird keepers" develop these abilities to carry on their tasks as 2bird keepers". Therefore, the abilities of "bird keepers" is the correct topic of this paragraph.