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PREDATION

PREDATION. Mobbing (pursuit deterrent; drive pred away). Alarm (Prior to or during attack). Distress***. For pred. +. -/ 0. Detectability. For prey. +. +. For pred. -. +. Localizability. For prey. +. 0/ +. Broad-band raspy sounds. High see.

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PREDATION

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  1. PREDATION

  2. Mobbing (pursuit deterrent; drive pred away) Alarm (Prior to or during attack) Distress*** For pred + -/0 Detectability For prey + + For pred - + Localizability For prey + 0/+ Broad-band raspy sounds High see Avian Vocalizations – calls: alarm, mobbing, distress Table of Selective Pressures

  3. Convergence among raptor alarm calls • Response to similar selective pressures to reduce detectability and localizability

  4. Traits to minimize detectability: - Low amplitude e.g., BCCH alarm = 55dB; mobbing = 60- 65dB - Outside the auditory sensitivity of predator

  5. Traits to minimizelocalizability: - non-abrupt start/finish and unmmodulated to minimize timing of arrival differences - High frequency to eliminate localization based on phase (i.e., pressure) differences

  6. Mobbing calls: • Broad band • Modulated • Abruptness • Repeated • Loud

  7. INFO Recipient - Eavesdropper Alarm calls and Eavesdropping INFO Signaler Receiver (‘intended’) (sender) (recipient) Tufted Titmouse INTERCEPTIVE Templeton et al. Hetrick and Sieving

  8. Templeton et al Science 308:1934-1937 4.5 Saw-whet owl 4.0 Pygmy owl Cooper’s 3.5 Merlin 3.0 Peregrine Kestrel Number of D notes per call 2.5 Red-tail hawk Great-horned owl Short-eared owl Prairie 2.0 Gyrfalcon Great gray owl Bobwhite quail 1.5 Rough-legged hawk 1.0 Predator body weight Chickadee mobbing calls are referential to aspects of predation risk i.e., more D-notes signals smaller predator, greater risk

  9. CACH response to ETTI calls in response to predator ETTI calls in response to predator type

  10. INFO Recipient - Eavesdropper Alarm calls and Eavesdropping INFO Signaler Receiver (‘intended’) (sender) (recipient) Tufted Titmouse INTERCEPTIVE If titmice are effective as an advanced warning system, do you breed close to them or far away? How would you deign an experiment?

  11. INFO Recipient - Eavesdropper Alarm calls and Eavesdropping INFO Signaler Receiver (‘intended’) (sender) (recipient) Tufted Titmouse INTERCEPTIVE

  12. 60 ** ** 2009 2010 50 40 Random Relative proportion of occupied ETTI PB sites 30 NS 20 10 0

  13. Vocalizing and predator-prey interactions • predator-prey

  14. Any response 1) Playing petrel vocalizations to skuas Move towards

  15. 2) Playing skua vocalizations to petrels Number of singing bouts Silent control Kelp gull petrel chaffinch control

  16. 16 of 18 3-min intervals • veeries sang more in control • Control veeries sang more • 176.3 vs. 134.7 songs • and control veeries sang later • by 4.5 minutes

  17. In conclusion: • There is often a diversity of calls given to predator • These is a close fit between form and function • Calls may encode information about risk, urgency, predator type • The information about risk encoded in alarm calls is used by • interceptive eavesdroppers

  18. SOCIAL EAVESDROPPER INFO (C) (A) (B) INFO Signaler Receiver (‘intended’) (sender) (recipient)

  19. Non-overlapping Low aggression Overlapper = aggressive Overlapping High aggression Overlapped = passive

  20. Otter et al. 1999 ♂ ♂ ♂ ♂ EPCs in 2 of 20 aggressive owner’s nests i.e., low cuckolding In Otter et al’s work on tits there was no reproductive effect, But on Mennill et al’s work on red-winged blackbirds there was Aggressive owner ♀ ♀ Passive owner EPCs in 12 of 23 passive owner’s nests i.e., high cuckolding

  21. SOCIAL EAVESDROPPER INFO (C) Clearly Social Eavesdropping occurs by both sexes (A) (B) INFO Signaler Receiver (‘intended’) (sender) (recipient)

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