You will now read a short passage and then listen to a talk on the same academic topic. You will then be asked a question about

OK, yesterday we closed with a few remarks about how alarm signals vary depending on the nature of the threat perceived, especially on the type of predators. Consider the meerkat that lives in Africa’s Kalihari Desert. That’s mostly in Botswana and South Africa, if you cut your geography class.
Meerkats live in groups called mobs. Typically, while other meerkats are outside their burrows foraging or playing, there is one meerkat that stands guard. Researchers have observed how this sentinel’s alarms vary depending on the type of predators. For instance, when large birds like hawks, eagles, owls soar overhead, the guard gives a loud whistling cry that brings his mob mates scampering back to their burrows. But if a snake is spotted, the guard makes more of a barking sound, which has the other animals mustering together, shaking their bodies and scaring off the snake. The show of aggression here is easily accounted for. After all, meerkats are a type of mongoose and at least partially immune to most snake venom...but not to being eaten! No sensible cobra or mamba attacks a meerkat mob.