1. 7.1 Animals find food using a variety of sensory modalities Animals use several sensory modalities when searching for food (e.g., vision, olfaction, hearing) Natural selection favors sensory modalities that most efficiently and effectively provide information about the location of food From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press

6. 7.1 Animals find food using a variety of sensory modalities Mechanoreceptors – Used by fish for hearing, for detecting their body position, and for information about water pressure or movement Lateral line system – Mechanoreceptors that provide hydrodynamic information about water velocity and acceleration – Composed of neuromasts From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press

7. Catfish track the wake of their prey Research question: How do nocturnal catfish find food in the dark? (Pohlmann, Grasso, & Breithaup 2001) Hypothesis: Catfish use their lateral line system to detect cues (hydrodynamic, chemical) provided by the wake of their fish prey Prediction: Catfish will follow the wake of their prey while hunting From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

8. Catfish track the wake of their prey From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research Methods: – Observed catfish (Silurus glanis) hunting individual guppies (Poecilia reticulata) – Used an infrared video system to track the movement of both predator and prey in complete darkness – Classified movement sequences as “path following,” “head-on encounters,” or “attack on stationary guppy”

9. Catfish track the wake of their prey From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research Results: – 80% of attacks occurred on moving guppies – Catfish usually followed the same path as the guppy before the attack Conclusion: – Catfish appear to follow the path of their prey to find and attack them

10. Catfish track the wake of their prey Research question: Do catfish use chemical or hydrodynamic cues to track their prey in the dark? (Pohlmann, Atema, & Breithaup2004) From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

11. Catfish track the wake of their prey From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research Methods: – Used an infrared video system to track the movement of both predator and prey in complete darkness – Manipulated either the lateral line (reduced ability to detect hydrodynamic cues) or external gustation (reduced ability to detect chemical cues) and compared their behavior to that of controls – Classified hunting success and movement sequences of treatment fish

12. Catfish track the wake of their prey From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research Results: – Without lateral line, mostly head-on attacks and low capture rate Conclusion: – The lateral line provides important information for catfish to track the wake of their prey

13. Bees use multiple senses to enhance foraging efficiency Research question: Is foraging more efficient when multiple sense are used? (Kulahci, Dornhaus, & Papaj 2008) – Bees feed on nectar and pollen from flowers that vary in color and shape (visual cues), as well as odor (chemical cues) From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

14. Bees use multiple senses to enhance foraging efficiency Methods: – Trained individual bees (Bombus impatiens) to feed on artificial flowers – Flowers varied in shape and odor – Flowers with sugar water could provide a single or multiple cues that bees learned From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

15. Example of learning curves. Ipek G Kulahci et al. Proc. R. Soc. B 2008;275:797-802 ©2008 by The Royal Society

16. Mean number of visits (±s.e.) required to learn flowers in each treatment group. Ipek G Kulahci et al. Proc. R. Soc. B 2008;275:797-802 ©2008 by The Royal Society

17. Bees use multiple senses to enhance foraging efficiency Results: – Bees trained to use both visual and odor cues had the highest feeding performance Conclusion: – The use of multiple sensory cues facilitates efficient feeding From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

18. Mean flower visit rates (visits per second±s.e.), defined as the correct visits/total decision time. Ipek G Kulahci et al. Proc. R. Soc. B 2008;275:797-802 ©2008 by The Royal Society

19. Decision speed and accuracy during testing. Ipek G Kulahci et al. Proc. R. Soc. B 2008;275:797-802 ©2008 by The Royal Society There was a strong treatment effect as reflected in a difference among y-intercepts (R2=0.42, F3,27=6.56, p=0.001

20. From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press

22. 7.2 Visual predators find cryptic prey more effectively by learning a search image Many predators use vision to locate their prey This has favored the evolution of behavioral and morphological adaptations in prey to avoid detection This favors counteradaptations in predators to better detect hidden or cryptic prey Evolutionary arms race: back-and-forth process of adaptation and counteradaptation in two species From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press

25. Blue jays use a search image to find prey Research question: Do blue jays use a search image to find cryptic prey? (Pietrewicz & Kamil 1977; Pietrewicz & Kamil 1979) – Search image: visual distinctive features of an object, like a single prey type From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

26. Blue jays use a search image to find prey Methods: – Blue jays (Cyanocitta cristata) – Trained birds to search for moth images on a computer screen – Scored correct and incorrect responses to images (moth present or absent on screen) – Two treatments: Run treatment – birds were exposed to the same cryptic moth repeatedly (jays could form a search image) Nonrun – two different moths were presented randomly (jays cannot form a search image) From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

27. Blue jays use a search image to find prey Results: – In two run treatments, the percent of correct responses increased – In the nonrun treatment, the percent of correct responses did not change over trials Conclusion – Jays used a search image when the same cryptic prey was presented repeatedly, which resulted in a more efficient search From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

28. 7.4 The optimal patch-use model predicts how long a forager should exploit a food patch The marginal benefit of feeding in a food patch is the instantaneous harvest rate. Because of diminishing returns, the marginal benefit of feeding declines with time spent in a patch Diminishing returns – When a forager enters a food patch, it initially harvests food at a high rate. But as the patch is depleted, its harvest rate declines. From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press

29. 7.4 The optimal patch-use model predicts how long a forager should exploit a food patch The optimal patch-use model assumes: – Foragers attempt to maximize energy intake rate – All patches are identical – Travel time between patches is constant – The instantaneous harvest rate declines as a forager depletes a patch; the forager experiences diminishing returns in each patch This model is known as the marginal value theorem From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press

30. 7.4 The optimal patch-use model predicts how long a forager should exploit a food patch The optimal patch-use model predicts the optimal time to spend exploiting each patch From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press

31. 7.4 The optimal patch-use model predicts how long a forager should exploit a food patch The optimal time to spend exploiting each patch is affected by the travel time: – For short travel times, the optimal patch time is small – For longer travel times, the optimal patch time is longer From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press

32. Patch use by ruddy ducks Research question: How do ducks exploit food patches? (Tome 1988) Hypothesis: Ducks attempt to maximize energy intake rate according to the optimal patch-use model Prediction: Travel time will affect patch time according to the model From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

33. Patch use by ruddy ducks Methods: – Ruddy ducks (Oxyura jamaicensis) – Artificial food patches in a large aquarium – Birds fed on wheat grains buried in sand – Birds experienced diminishing returns in the patches – Tested six ducks From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

34. Patch use by ruddy ducks Methods: – Manipulated travel time between food patches – Compared food eaten from a patch for short and long travel times – Tested same six birds From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

35. Patch use by ruddy ducks Results: – The model accurately predicted the number of items eaten by most of the ducks From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

36. Patch use by ruddy ducks Results: – Birds spent more time in patches when travel time was long Conclusion: – Ducks attempted to maximize energy intake while feeding from the artificial patches From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

37. 7.4 The optimal patch-use model predicts how long a forager should exploit a food patch Optimal patch use with multiple costs When feeding, animals experience: – Energetic costs – Predation risk costs – Missed opportunity costs Brown’s patch-use model incorporates these costs Model predicts that patches with identical benefits and costs should be harvested down to the same quitting harvest rate From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press

40. Gerbil foraging with variable predation costs Research question: How does variation in predation costs affect patch use? (Kotler, Brown, & Hasson 1991) Hypothesis: Foragers will use patches less when predation costs are high Predictions: Gerbils will feed less from open patches compared to patches under brush when owl predators are present and when illumination level is high From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

41. Gerbil foraging with variable predation costs Methods: – Allenby’s gerbil (Gerbillus allenbyi) and Egyptian sand gerbil (Gerbillus pyramidum) – Allowed gerbils to feed (seeds) from food patches filled with sand – Patches were either in the open or covered by brush – Manipulated presence/absence of owl predators and illumination level (illuminated/not illuminated) – Measured seed left in patches (GUD) From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

42. Gerbil foraging with variable predation costs Results: – GUDs were lowest for patches under brush – GUDs were highest when owls were present and for illuminated trials Conclusion: – Gerbil foraging behavior is affected by predation risk costs as predicted by Brown’s model From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

43. Applying the Concepts 7.1 GUDs and conservation – Many nocturnal animals perceive a higher risk of predation when light levels are high – Humans add artificial light to many environments, which can negatively affect rare species – Santa Rosa beach mice strongly reduce foraging effort (leave higher GUDs) near artificial lights – This represents a reduction in the quality of their habitat From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Applying the Concepts

44. Incomplete information and food patch estimation The optimal patch-use model assumes animals know the quality of encountered patches However, many foragers will need to estimate food patch quality Animals can combine sample information from a patch with prior knowledge about the distribution of patch types in the environment, using Bayesian estimation From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press

47. Bayesian foraging bumblebees Research question: Can bumblebees estimate food patch quality in a Bayesian manner? (Biernaskie, Walker, & Gegear 2009) Hypothesis: Foragers combine prior knowledge of the distribution of patch types with sample information to estimate patch quality Predictions: Bees trained in a uniform environment (all patches the same) will exploit patches differently than bees trained in a high-variance environment (half the patches are rich; half the patches are poor) From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

48. Bayesian foraging bumblebees Methods: – Trained bees to feed from a patch of 12 artificial flowers – Half the bees were trained in a uniform environment – Half the bees were trained in a high-variance environment – Observed propensity to depart a patch (estimate of patch quality) From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

49. Bayesian foraging bumblebees Results: – Bees trained in the high- variance environment had a high propensity to stay in a patch – Bees trained in the uniform environment had a low propensity to stay in a patch Conclusion: – Bees appear to combine prior knowledge of patch type distribution with sample information to estimate patch quality From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

50. 7.3 The optimal diet model predicts the food types an animal should include in its diet The diet model assumes: – Foragers maximize fitness by maximizing energy intake rate – Food items are encountered one at a time in proportion to their abundance – Food items can be ranked by their profitability Profitability = energy / handling time Handling time = time to manipulate item prior to consumption From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press

51. 7.3 The optimal diet model predicts the food types an animal should include in its diet The diet model example: – The optimal diet is to always consume types A, B, and C while always ignoring types D and E Zero-one rule: Each food item is either always eaten or always rejected From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press

52. Diet choice in northwestern crows Research question: Why do northwestern crows reject some clams while foraging? (Richardson & Verbeek 1986) Hypothesis: Crows attempt to maximize energy intake rate according to the optimal diet model Prediction: Crows should eat all clams greater than 29 mm in size and reject all clams < 29 mm in size. From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

53. Diet choice in northwestern crows Methods: – Northwestern crows (Corvus caurinus) – Recorded the size of clams that were eaten and the size of clams picked up but not eaten (rejected) – Measured handling times of differently size clams – Measured energy content of differently size clams From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

54. Diet choice in northwestern crows Results: – Clams > 30 mm were almost always eaten – Clams < 28 mm were almost always rejected Conclusion: – Observed crow diets are similar to the one predicted by the diet model From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

55. Ant foraging: the effect of nutrients Research question: How does the need for sodium affect diet choice? (Kaspari, Chang, & Weaver 2010) Hypothesis: Sodium limitation affects the feeding behavior of ants Prediction: Ants living in environments where sodium is rare will have a strong preference for sodium chloride (NaCl) From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

56. Ant foraging: the effect of nutrients Methods: – Examined recruitment to food vials by Tapinoma sessile along four transects – Half the vials contained sucrose, half contained NaCl – Transects were 1, 10, 100, and 1000 m from a road that was salted with NaCl each winter – Recorded the number of sucrose and NaCl vials that contained ants along each transect From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

57. Ant foraging: the effect of nutrients Results: – Close to the road, less than 10% of vials visited by ants contained NaCl – Ants recruited to NaCl vials more strongly as distance to the road increased Conclusion: – Sodium limitation affects feeding behavior From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, © 2014 by Oxford University Press Featured Research

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