Psych 1000 CH 14 WHY DO Birds SING MORE THAN ONE SONG D. Logue PDF

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CH 14 WHY DO BIRDS SING MORE THAN ONE SONG? PSYCH 1000 DAVID M LOGUE Source: Textbook The Repertoire Problem  Songbirds learn songs -use to attract mates, repel rivals  Ovenbirds & white-crowned sparrows have 1 song type in repertoire  Brown thrasher 1500 types  Humans have repertoire learned vocals = vocabulary  American Robin 13 songs  Birdsong most complex aside from human, 2 systems  72% sing more than 1 song Repertoires Within Repertoires  “Notes” - uninterrupted units of sound often  Notes in a group- syllable  Skylark produces syllables & not songs  Most songbirds sing “Songs”  “Song”- discrete strings of syllables, separated from other strings by silent gaps  House wren - 27 syllables, combined to make 200 songs  Black-capped chickadee: fee-bee songs; vary pitch by shifting 2 notes eg “chick-a-feebee & fa-fee-bee” Three Philosophical Questions  What is the meaning of “function”, why don't some birds sing repertoires?  What advantage did Lg repertoire males have over small? - lg repertoires more attractive to females, therefore had more offspring.  Repertoires dont always evolve to get larger. Small repertoires req less investment in brain tissue (brain tissue hypothesis) So Why Do Birds Sing More Than One Song?  4 hypothesis: 1. Nothing: repertoires are epiphenomena (epiphenomena: something has no consequences) 2. interchangeable variety- specific acoustics dont matter but variety does 3. functionally distinct signals 4. Female preference hypothesis - female birds prefer males w larger repertoires

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Beau Geste Hypothesis: variety matters, acoustics don’t. Birds use different locations to sing songs to create illusion many birds singing. Beau geste hypothesis inconsistent, unsatisfactory monotony principle: based on idea listeners hear same song repeated over/over, respond less over time aka “habituation” Anti-exhaustion hypothesis- says repertoires prevent effects of monotony on singers. Bird vocal systems dont exhaust from repeating same movements over/over

Ability to Match/ not Match  Song matching - learning from neighbours or settling in neighbourhood w similar repertoires. *may be way to identify rival Matching signals means aggressive intent  Match signal alignability - Logue & Forstmeire alternative hypothesis: not aggressive, allows alignability. (lessens difference between choices) Different Songs, Different Functions  Do bird songs have work-like meaning like human vocabulary? - No  Human language relies on “recursivity”= infinite range expression, finite signal  Animal communicate exclusively about the present  Different functions- males canaries sing “sexy syllables” @ fertile females  Some sing different songs during breeding season Conclusion  8 answers to why birds sing more than 1 song 1. Epiphenomenon 2. Beau Geste 3. Anti-exhaustion Hypothesis ~ Have all shown they cannot explain repertoire function, but Logue rejects those ideas 4. Song type matching- aggressive intent (mixed reports) 4. Alignability - only tested on 1 species 4. Found support for “Monotony-threshold” 4. Female Preference 4. Different functions hypotheses Sexual selection/natural selection driven song selection (Charles Darwin): Process which some birds reproduce more than others because of abilities to access mates *Song repertoires are not like vocabularies b/c animal communication isn't like language. -birds lack complex societies and cognitive capacity for language -natural selection does NOT drive animals communication systems towards human language ________________ PSYCH 1000 CH 14 LECTURE D. LOGUE ` Logue Lecture 2 : “Are Bird Songs Like Vocal Gymnastics” 2 Hypotheses re: performance 1. Song structure correlated w singer’s quality eg relationship between good mate & ability to sing - mixed evidence, can only tell age, mass by sound sometimes. Song performance influences attractiveness 2. Listeners adapt to decisions based on correlation Performance

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Birds can show vigor by ability to sing

Motor constraints  Frequency modulation  Amplitude modulation- note rate Jeff Potos - studied sparrows, trill rate/bandwidth. Can’t have high bandwidth & high trill rate.

Physiology of Song Production  Song produced in syrinx, change shape of mouth to filter sound  Has to move upper vocal tract and coordinate w syrinx  As frequency bandwidth increases, minimum note duration increases 

Songs are sexual signals; given by males*, assessed by males & females...