But the alarm call is a fact about the signaller—it conveys the fact that it is aware of the predator. For a bird to give the alarm call without being aware of a predator, it would have to do it a lot more often, wasting precious time and energy. Dishonest signal is more expensive than honest signal because a bird that sounded the alarm because it noticed a predator can minimize the alarm time and get back to whatever it was doing as soon as the predator is gone.
There are actually two types of alarm calls: those addressed to one’s group members and those addressed to the predator. The ones addressed to group members don’t necessarily convey meaningful information about the sender (at least this is not the immediate purpose, although these signals can in some cases have an additional benefit of demonstrating ones high quality to group members, see my other comment).
The alarm calls addressed to the predator are thought to signal the sender’s vigilance: “you’ve been spotted, we know you are here, you can’t catch us”. See mobbing. These calls often result in the predator politely taking a leave.
But the alarm call is a fact about the signaller—it conveys the fact that it is aware of the predator. For a bird to give the alarm call without being aware of a predator, it would have to do it a lot more often, wasting precious time and energy. Dishonest signal is more expensive than honest signal because a bird that sounded the alarm because it noticed a predator can minimize the alarm time and get back to whatever it was doing as soon as the predator is gone.
There are actually two types of alarm calls: those addressed to one’s group members and those addressed to the predator. The ones addressed to group members don’t necessarily convey meaningful information about the sender (at least this is not the immediate purpose, although these signals can in some cases have an additional benefit of demonstrating ones high quality to group members, see my other comment).
The alarm calls addressed to the predator are thought to signal the sender’s vigilance: “you’ve been spotted, we know you are here, you can’t catch us”. See mobbing. These calls often result in the predator politely taking a leave.