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Questions and Answers
Which of the following is NOT a benefit of higher net energy gain?
Which of the following is NOT a benefit of higher net energy gain?
What happens to the average searching time as the number of prey types increases?
What happens to the average searching time as the number of prey types increases?
Which term describes the optimum point in prey consumption strategy?
Which term describes the optimum point in prey consumption strategy?
What is the primary goal of optimal foraging theory?
What is the primary goal of optimal foraging theory?
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If a predator finds a less profitable prey type (P2) while searching for a more profitable one (P1), what factors should it consider?
If a predator finds a less profitable prey type (P2) while searching for a more profitable one (P1), what factors should it consider?
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Which statement best describes the relationship between benefits and costs in optimal foraging theory?
Which statement best describes the relationship between benefits and costs in optimal foraging theory?
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What does the profitability of a prey type represent in simple terms?
What does the profitability of a prey type represent in simple terms?
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How does the average handling time change with an increase in prey types?
How does the average handling time change with an increase in prey types?
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How is search and acquisition costs in foraging often measured?
How is search and acquisition costs in foraging often measured?
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What is represented by Ts and Th in the strategy of prey consumption?
What is represented by Ts and Th in the strategy of prey consumption?
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What type of foraging mode has a low capture rate but low metabolic cost?
What type of foraging mode has a low capture rate but low metabolic cost?
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What should a predator do if the handling time of P2 is low but profitability is still lower than P1?
What should a predator do if the handling time of P2 is low but profitability is still lower than P1?
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What factor is NOT considered when evaluating food resources in foraging?
What factor is NOT considered when evaluating food resources in foraging?
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Which formula expresses the optimal foraging strategy?
Which formula expresses the optimal foraging strategy?
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In feeding experiments, which of the following might influence a predator's prey preference?
In feeding experiments, which of the following might influence a predator's prey preference?
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Which foraging mode is characterized by high endurance and a high capture rate?
Which foraging mode is characterized by high endurance and a high capture rate?
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What aspect of food resources is described as 'spatially unpredictable'?
What aspect of food resources is described as 'spatially unpredictable'?
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What should a consumer do if it encounters the most valuable prey at a low frequency?
What should a consumer do if it encounters the most valuable prey at a low frequency?
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In which environment are animals likely to be specialists?
In which environment are animals likely to be specialists?
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What is the optimal strategy for a predator when the handling time of a food item is high?
What is the optimal strategy for a predator when the handling time of a food item is high?
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What prediction can be made about a consumer's diet as the productivity of its environment declines?
What prediction can be made about a consumer's diet as the productivity of its environment declines?
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What is a key consideration for a consumer when deciding how long to forage in a patch?
What is a key consideration for a consumer when deciding how long to forage in a patch?
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How does an animal optimize its foraging in a highly profitable patch?
How does an animal optimize its foraging in a highly profitable patch?
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What does optimal foraging theory specifically advise organisms to maximize?
What does optimal foraging theory specifically advise organisms to maximize?
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Why should a predator choose the most profitable food item?
Why should a predator choose the most profitable food item?
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What do animals tend to do when richer patches are available?
What do animals tend to do when richer patches are available?
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What did the simulation predict regarding female behavior on different egg patches?
What did the simulation predict regarding female behavior on different egg patches?
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What does maximizing B/C in foraging models suggest about animal behavior?
What does maximizing B/C in foraging models suggest about animal behavior?
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How did females respond to patches of varying egg health?
How did females respond to patches of varying egg health?
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What conclusion can be drawn about the predictions of optimal foraging models?
What conclusion can be drawn about the predictions of optimal foraging models?
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What factor does NOT influence the length of time an individual stays in a resource patch according to the marginal value theorem?
What factor does NOT influence the length of time an individual stays in a resource patch according to the marginal value theorem?
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When should a consumer leave a resource patch based on the marginal value theorem?
When should a consumer leave a resource patch based on the marginal value theorem?
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What does the term Gopt represent in the marginal value theorem?
What does the term Gopt represent in the marginal value theorem?
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In the context of the marginal value theorem, how does increasing travel time affect foraging behavior?
In the context of the marginal value theorem, how does increasing travel time affect foraging behavior?
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According to the marginal value theorem, which scenario would result in a consumer spending more time in a resource patch?
According to the marginal value theorem, which scenario would result in a consumer spending more time in a resource patch?
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What happens to the rate of energy gain once foraging is initiated in a resource patch?
What happens to the rate of energy gain once foraging is initiated in a resource patch?
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If two patches have the same quality but different distances, what does the marginal value theorem suggest about the time spent in each patch?
If two patches have the same quality but different distances, what does the marginal value theorem suggest about the time spent in each patch?
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How do animals generally behave regarding resource patches based on the marginal value theorem?
How do animals generally behave regarding resource patches based on the marginal value theorem?
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Study Notes
Optimal Foraging Theory
- Foraging is the suite of activities involved in exploiting a resource, often food, but can include nesting materials or mates.
- Optimal foraging theory aims to understand how animals choose food sources to maximize the net rate of energy gain.
- Key questions include: What foods should animals include in their diet? How long should they spend feeding in a given location?
- The theory emphasizes an economical approach, balancing benefits (energy gain) against costs (search and handling time).
- Profitability is calculated as energy gained divided by the search + handling costs.
- Optimal foraging theory predicts that animals will choose the most profitable food items available.
- Prey types vary spatially (predictability of availability), temporally (predictability of availability), based on unequal quality (size) and accessibility, e.g. proximity to the nest.
Foraging Modes of Predators
- Sit-and-wait predators (ambush): have low capture rates, low metabolic costs, low learning capacity, and high diet breadth.
- Active predators (cursorial): have high capture rates, high metabolic costs, high learning capacity, and low diet breadth.
Predictions about Animal Diet
- If encounter rates for a preferred prey type are high, a consumer will be a specialist.
- If encounter rates for a preferred prey type are low, a consumer will be more of a generalist.
- An animal's diet can shift as environmental productivity declines or if more profitable food types become unavailable.
Where to Eat?
- Landscapes are often mosaics of patches of differing quality.
- Optimal foraging theory suggests that consumers should maximize the rate of energy gain per unit of time spent foraging in a particular patch.
- The marginal value theorem (Charnov, 1976) predicts the optimal time a consumer should spend foraging in a given patch. The time factor considers travel time to the patch, patch quality (prey density), and time required to extract the resource.
- As resources in a patch begin to deplete, the rate of energy gain decreases, thus the marginal value theorem describes the optimal moment to leave a patch.
Marginal Value Theorem & Patch Quality
- Animals prefer high quality patches over lower quality patches when the distance between patches is similar.
- Patches of differing quality, but similar distances from the forager, will attract animals based on the resources available, not just distance. For example, optimal foragers prefer a patch with more quality resources (and stay longer) even if a high quality patch is more distant.
- Optimal foraging theory can account for prey types varying in density and energy yield, and predict, based on these factors, whether a consumer will exploit more or less time in the given patch.
Conclusions
- Animal foraging behavior appears to depend on simple decisions resulting in optimal behavior, even with factors like competition or predation limiting the foraging animal.
- Optimal foraging models are useful tools for predicting animal behavior, given the assumption that consumers maximize their energy gain.
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Description
This quiz assesses your understanding of optimal foraging theory as it applies to glaucous-winged gulls. Explore concepts like net energy gain from different prey types, foraging strategies, and the implications for predator behavior. Answer questions that challenge your grasp of energy calculations and prey profitability.
