Animal Behaviour-Foraging Flashcards
Why is foraging optimally beneficial?
This allows maximum input whilst minimising energy output
What two factors affect individual economic decisions?
Time spent foraging (searching, handling and commuting) and quality of food (number/amount, nutritional content)
The graph for time spent and number of preys the individual should catch to make it worth while is curved not linear. If commute time is short, what is the most beneficial way of collecting prey?
Taking many trips and few prey. If long commute time, more beneficial to stay a while and collect more prey
What is the Marginal Value Theorem?
It is the model that allows optimal foraging between patchy food distribution. Animals must make a decision on when to leave the patch of food as resources become depleted
Why does the reward graph feature a curve in patchy food distribution?
Resources/returns diminish the longer an animal stays there so eventually the curve of reward slows down
What are the two points that came out of testing the curve for patchy food distribution?
The greater the distance between the patches, the longer the animal should stay.
The poorer quality the patches, the longer the animal should stay as they need to make their trip worth while
Crabs are selective when it comes to the size of mussels they handle. Why is this? Why do they sometimes pick small or large mussels over their preferred size?
They want to receive optimal profitability (easy to open with large return). Sometimes they do not have the choice as search time is also costly and therefore handle small or very large prey to survive. Eating small prey items completely depends on the abundance of large prey items as large prey items are always preferred
What are the benefits of foraging in groups?
Information about where food is- Food is often spatially and temporally ephemeral
Food defence- e.g ravens can protect carcasses etc, naive birds often follow knowledgeable ones
Predator avoidance- larger pigeon flocks saw Gohawks and escaped
Can catch more and more difficult prey- e.g dolphins and fish
What are the costs of foraging in groups?
Prey startling and competition, not all positions equal- exploitation (can’t eat what someone else is eating)
(Maybe look at Ecology scattered and equal comp)
What is the Ideal Free Distribution model?
There will be a higher density of competitors in an area of more food/prey
The Ideal Free Distribution model does not always work in real life. What can change?
Unequal competitor distribution may lead to resource defense- e.g cottonwood aphids choose prime locations on leaves (mid-rib) to get most nutrient rich sap. Those who fight and lose have to go elsewhere with lower nutrient content
