CHAPTER 16: Predation
by
Pat Geare
What is Predation
TYPES OF PREDATION
Carnivory- The most common form associated with predators. This basically is an animal that feeds on meat.
Parasitoidism- In this situation, one organism lives off another, harming it. This is thought of as flies laying eggs on a host body.
TYPES OF PREDATION cont.
Herbivory- This types is described as an animal feeding on plants.
Cannibalism- When the predator and its prey are both the same species.
Predator Responses
There are two different ways the predator species can respond to increased prey density.
1. Each predator kills more prey, to keep the number regulated. (Functional Response)
2. Increased reproduction by the predators, this lessens the ratio of prey:predator. (Numerical Response)
Predators Search Image for Prey
Search Image- Mental image formed in predators, it enables them to find the prey more quickly and efficiently.
This basically means that when a predator finds a prey it likes, it focuses on that one species. So it becomes harder for another species to become their main prey.
Predators Turn To Alternate Prey
Even though a predator may have a strong liking for a certain species, that species may become extinct or become endangered.
If this happens the predator will have to adapt to another prey, to compensate for the low number of food.
Hunting Tactics
There are three general hunting methods.
AMBUSH
STALKING
PURSUIT
AMBUSH
This is when an animal just waits for an animal to come along.
Typical with frogs, alligators and crocodiles, and lizards.
This type doesn’t require much energy, but it doesn't have a high success rate.
STALKING
This can been seen in many cats and birds.
The animals searches a long time, but when the prey is spotted, the attack and hunt is short and efficient.
PURSUIT HUNTING
This is the tactic for hawks, lions and wolves.
This is what you think of when you picture animals hunting.
Herbivores
Herbivores forage so they will have food over the harsh winters.
Foraging- Animals seek food and store it for later use, if food is not easily found.
This is common among birds and small rodents.
Plants, Herbivores, and Carnivores Interact
This is a cycle that is followed all throughout nature.
The common analogy is vegetation, snowshoe hair and a lynx.
The hair’s existence depends both on the vegetation and the lynx.
When the amount and quality of plants decrease, the hair experiences malnutrition.
Plants, Herbivores, and Carnivores Interact
When the hair is malnutritioned it becomes vulnerable to its predator, the lynx.
This causes the decline of the hair population, but increase in the lynx population.
When the hairs are on a decrease, this gives the plants time to rebound its abundance back to normal.
When the winter comes, the winter food increases, making the lynx’s need for the hair as a source of food lower.
Plants, Herbivores, and Carnivores Interact
After all this is done, the whole cycle starts over again for another season.