6%20Nov%20Foraging - S 1 = S 2 But as Type 1 preferred, S 1...

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144: Foraging 6 Nov 09 1 Foraging Decisions • What to eat? –Item choice –Constraints of nutrition • Where to eat? –Patch choice –Constraints of risk What NOT to eat? taste aversion learning • Prey needs predator to learn quickly –Warning coloration –Mimicry • Predator needs to learn quickly –Poisonous Inedible Flavor predicts nausea Sound predicts shock Insectivorous bats = typical mammal Vampire bats - no taste aversion
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144: Foraging 6 Nov 09 2 • Whelks on shore • Only take large • Drop from 5.23 (+ .07) meters • Why? 15 m tower Fewest drops = L Smallest height = 5 m Therefore L @ 5 m = optimal Switch to worse when good are rare E = caloric gain h = handling time S= search time E 1 /h 1 > E 2 /h 2 Type 1 more profitable when
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Unformatted text preview: S 1 = S 2 But as Type 1 preferred, S 1 increases Now Type 2 is more profitable ( E 2 / h 2 ) > E 1 /(S 1 + h 1 ) When to switch? At S 1 S 1 > ((E 1 h 2 )/ E 2 ) - h 1 S 1 = threshold search time Where to forage? Patch choice Where is the competition worst? Ideal Free Distribution Match group size to rate of food ??? 144: Foraging 6 Nov 09 3 Ducks match bread-throwing rate Other factors: predation Dugong (Shark Bay) Sea grasses: cropping vs. excavation Other factors: starvation Yellow-eyed junco Two patches Variable 0 or 10 seeds Constant Always 5 Choice varies with temperature Cold , choose Variable Warm , choose Constant...
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6%20Nov%20Foraging - S 1 = S 2 But as Type 1 preferred, S 1...

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