PredatorPrey Interactions The predators view foraging behavior Optimal
Predator-Prey Interactions The predators view: foraging behavior
Optimal Foraging • Predators have a range of foraging choices – – Where to search What time to search What to eat How long to spend eating or trying to eat
Foraging Models – Analyze costs and benefits of foraging decisions – Goal: predict how animal should behave to max fitness – How do we typically measure fitness?
Types of Models Prey Models Patch Models
Assumptions • • • Maximize E gain Can’t handle & search Prey recognized instantly Prey encountered randomly Handling costs same Travel & searching have equal costs
Example: prey model • Davies (1977) on Pied Wagtails • Question: does size of the prey influence foraging decisions • What is calorie payoff compared to fly size? • What would handling time compared to size look like? • What will calories/sec handling time look like? • What do you predict birds will do? https: //www. yout ube. com/watch? v= MP 0 DFVO 16 Zk
Patch Model Question: how long should individual forage in a patch before leaving to find a new one? Goal: maximize rate of energy gain (most food least time)
Example: Patch model Question: How many prey collect before returning to the nest? Predictions: • Longer travel = ? • Shorter travel = ? Number of Prey Bryant and Turner, 1982 0. 1 0. 45 1. 0 Distance from Nest (km)
Why were the actual prey loads not perfectly optimal? What types of conditions might prevent animals from foraging optimally? 12
Trade-offs with Foraging Dietary Constraints Can only process 32 kg
Trade-offs with Foraging Predation • How will animals modify foraging decisions with risk of predation? Think about: • Patch choice • Choosing prey • Total time 14
Trade-offs with Foraging Predation
Trade-offs with Foraging Territorial Defense
Trade-offs with Foraging Jackman, 1994. Field experiments on prey selection in bald eagles 17
Is there anything else that could effect foraging decisions? • Example: yellow-eyed Junco
Risk-Sensitive Foraging • Previous examples look at long-term rate of E gain • Animals can also respond to variation in food availability
Morphological and Behavioral Adaptations to catch prey http: //www. youtu be. com/watch? v= w-a. ILn. Sk. MXU Eisner et al. 1978, 1997
Luring • • • • as. vanderbilt. edu//catanialab/research/tentacled-snakes/ youtu. be/9 XCPK 5 Jy 8 y. A youtu. be/WXt. N 9 PER 5 UE youtu. be/t 0 KT-pec 6 Cw youtu. be/BR-GR_ds. ABQ youtu. be/3 qe 2 p. OD 7 EH 8 https: //youtu. be/z_Oi. BIOk. Ko. U https: //youtu. be/RT-VX 031 C 6 I https: //youtu. be/_UCmmm. TVe. JU https: //youtu. be/txlu. LEgmb. Dg https: //youtu. be/c 2 PVa. FWOQAE https: //youtu. be/N 2 Nf 8 u. MOZ 2 c https: //youtu. be/o. I 0 IE 5 i. QDZo https: //youtu. be/S 1 k 99 sb. KQh. I https: //youtu. be/Jujx. Vr 2 immk https: //vimeo. com/2546558 21
Morphological and Behavioral Adaptations to catch prey http: //www. youtube. com/watch? v=v. Jvfji. CTvq 4 Earle 1979, Sharpe and Dill 1997 https: //www. youtub e. com/watch? v=wl 12 0 Ruh. QYg
Morphological and Behavioral Adaptations to catch prey http: //www. youtube. com/watch? v=nn. YW 0 j. E 7 -Ik
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https: //www. youtube. com/watch? v=1 p 2 AI 9 u. Ts 0 25
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