Professor:
Ok, so we were talking about predators and the behavior of predators... And how some behavior of predators are learned and some are innate... and when we were looking at the behaviors of predators, we talked about how predators hunt... how they hunt prey... that is other animals... we have discussed how some of the predators' behavior like sneaking up on an animal might be learned and how other behavior like... chasing their prey might be instinctual. In fact, when an animal runs from a predator, it excites the predator and the predator will chase the animal basically on instinct.
Now, because many predators kill only when their prey is moving, an animal that pretends to be dead may succeed in convincing a predator to lose interest and move move along ... move along in search of more quote, unquote(used parenthetically to indicate the beginning and end of a quotation.), lively prey. And a lot of this can happen on instinct as well... And that's what I would like to talk about today the behavior of prey and how that behavior can be instinctual or learned as well. Some of this behavior even the innate behavior can be quite complex... and that's what I would like to focus on first, the complex innate behavior of prey. For instance, hognose snakes have a complex repertoire of anti-predator behaviors... one of these anti-predator behaviors is feigning death. These fairly large non-venomous, to slightly venomous, snakes live in sandy areas of the eastern United States. When a hognose snake is first disturbed, it opts to ' bluff the predator first — that is, it flattens and expands the first... front third of its body and head, forming a hood, causing it to look larger. It then curls into an exaggerated s-shaped coil and hisses, occasion...occasionally making false strikes at its tormentor. All that acting usually convinces the predator that the snake is venomous and therefore dangerous. But that does not always work. If the predator decides to investigate further... and further provokes the hognose snake, it drops the bluff and begins to twist
its body violently. Then it rolls onto its back with its mouth open and tongue hanging loosely out. This bluff.is designed to trick the p... predator into thinking the snake is 'dead. As I said, most predators will pass on dead prey. If the predator loses interest in, uh, the "corpse" and moves away, the snake slowly rights itself and crawls off. This complete repertoire of anti-predator mechanisms (automatic self-protective behavior) occurs in even young hognose snakes.
Student:
Excuse me, Professor Dundy, is that how we know the behavior is innate because we can observe it at a young age?
Professor:
In a nutshell, the answer is yes. But this is an important point, so I think I'll expand "expand upon it for a while. While most innate behavior is simple, simple when compared to learned behavior, the innate behavior we are talking about it here is very complex. We believe it is innate because we can see it, even in its mo... most complex forms in very young hognose snakes. Well, researchers have shown that newborn snakes are capable of making very subtle assessments... subtle calculations... of the degree of threat posed by a particular predator. Two experiments were conducted in which the recovery from death-feigning... that is the time it took snakes to recover from their fake death and crawl away was measured... so this was measured in newly hatched snakes under various conditions. In one experiment the recovery of snakes was monitored in the presence or absence of a stup... a stuffed screech owl mounted on a tripod one meter from the overturned snake. In another experiment, when the snake recovered in the presence of a human staring at the snake from a distance of one meter, in the presence of the same person in the same location but with eyes averted, and in a control condition in which no human was visible. In the first two instances, both the presence of the owl and, uh, the direct human gaze resulted in longer recovery times relative to the respective control conditions. On the other hand, when the human eyes were averted, the recovery time was immediate. Thus, young snakes are capable of using rather subtle p... cues to make adjustments in their anti-predator behavior. And all this seems to be instinctual. That is, hognose snakes do not have to learn this from their parents.
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