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Notes 5Mar - Animal Behavior Notes Chapter 7(cont from...

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Animal Behavior Notes Chapter 7 3/5/08 (cont. from notes!) iii) Constraints—On choices/payoffs Ex: Nutritional limits--People who ate more spices in India are the ones who lived, so they passed on those genes. Ex: Nutritional limits—Put limestone in tortillas (limestone = calcium carbonate). Problem i) Currency to measure ii) Constraints iii) Objections: circular Response: productive if supported with experiments Diet selection : BBc theorem- Not looking for weak and sick, they are just looking for food. Weak and sick are slower and easier to catch. Prey detection - oddity preference? Do animals prefer odd prey? Ex: Stickle backs ate the odd color of daphnia (when they were numerous) When there were not a lot of daphnia , stickle backs ate the normal ones Search Image : Nonrandom prey selection, S-shaped functional response -IF they are just eating what’s out there, you would assume to see a linear, increasing line… -The graph looks like an s… they are not eating randomly! Neophobia = opposite of curiosity -Mouse is avoiding cocoons because it doesn’t know what it is Social facilitation = doing it because everyone is -Mouse starts eating cocoons because all the other mice are Predictions from optimal foraging: -Choose most profitable food available -More selective when profitable items amore common -Ignore unprofitable items -Plenty: selective. Scarcity: broader diet. Ex: Barn Owl -Nest is tree cavities, forage over home range of several kilometers eating small mammals and rodents. 90% white footed and house mice, <5% meadow voles predict : eat 90% m: 5% v actual : eat 70% v
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Profitability = Energy gained/Search costs + handling costs Voles>mice Ev/Sv+Hv>Em/Sm+Hm Hypothesis: Mice are doing a better job of hiding- it takes longer for the barn owls to find them Ex: Northwestern Crows observe: 1. large whelks 2. 5m height 3. repeated effort predicts : gains>costs, have to go to 5m for optimal breakage actual : predictions supported! # of drops per whelk (graph) height of drop (m) *Net kcals : large whelks: 1.5 kcal medium whelks: -0.3 kcal small whelks: <<<< 7.1 Discussion Question In some places, American crows open walnuts by dropping them on hard surfaces. Unlike northwestern crows opening whelks, American crows reduce the height from which they drop walnuts from about 3 meters the first drop to about 1.5 meters on the fifth drop. If
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