EEB386H1 Final: Study Guide Notes (Life cycles, Song, Courtship, Reproduction, Feeding, Conservation)

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University of Toronto St. George
Ecology & Evolutionary Biology
Michael Denny

LECTURE 6 – LIFE CYCLES  Acts as neuro-hormone on brain to control Introduction aggressive behaviour (chasing + fighting)  Activates sexual behaviour (song + courtship)  4 components of annual cycle:  In male white-crowned sparrow + other temperate o Breeding o Moult breeding birds, testosterone surge when males set o Wintering up territories + chase intruders o Migration  Gonads regress when incubation begins  High testosterone levels interfere w/ parental care  Success in one stage depends on previous stage so need lower levels in breeding season  Energy storage/transfers important o EX: Need to have pre-migratory fattening before migration Timing of Breeding  Sometimes have to skip a stage (Breeding)  Reproductive system stimulated by long days (esp. for spring breeding birds)  Ultimate control of annual cycles: Seasonality + 1. Fall = short days switch reproductive system effects on food supply on  Proximate control of annual cycles: Endogenous o Reproductive system becomes rhythms linked to daylength photosensitive so that can grow gonads in response to ↑ daylength later on Breeding 2. Spring = long days stimulate hypothalamus:  Birds = seasonal breeders (don’t breed all year o Hypothalamus secretes GnRH round) o GnRH acts on pituitary  Birds = long day breeders (mate, incubate, rear young in spring + summer when daylength is o Pituitary secretes luteinizing hormone + follicle stimulating hormone increasing) o Hormones act on gonads  Have rapid development times 3. Incubation begins o = can complete breeding cycle during o Adults lose response to long days warm period  Mammals (sheep + cows) = short-day breeders o By mid-summer are photorefractory 4. Photorefractoriness is gradually lost, adults o Mate in fall, gestation occurs in winter become photosensitive again o Still rear young in spring + summer (peak o Restarts annual cycle food abundance) Hypothalamic-Pituitary-Gonadal (HPG) axis Biological Clock  Seasonal breeding regulated by HPG axis  Daylength (photoperiod) predicts onset of breeding, moult, migration  Breeding season cues: High light, temperature,  Circadian clock depends on light food availability, social stressors  Circadian pacemakers in eye, pineal gland, SCN o Neurons in hypothalamus of brain integrate (superchiasmatic nucleus in hypothalamus + brain) signals o Synthesize + release neuro-hormones  EX: White crowned sparrow: o Sensitivity to daylength ↑ as daylength > 12 (gonadropin-releasing hormones = GnRH) hours o Hormones act on anterior pituitary gland o Sensitivity to daylength ↓ as daylength < 12 that release gonadotropins hours o Gonadotropins act on gonads to stimulate spermatogenesis + oogenesis  = Clock doesn’t initiate hormonal changes o Gonads secrete sex steroids (testosterone,  Differences in photosensitivity between estrogen, progesterone) populations = geographic variation in onset of o Steroids activate reproductive behaviours, breeding stimulate development of secondary sex o Pop’n at low latitudes breed earlier characters (breeding/plumage) o Have trigger point at 13 hours of daylength o Arctic breeding population needs 15 hours Testosterone of daylength before gonadal changes  Gonadal hormone in males triggered  Activates spermatogenesis Breeding and Food Abundances Moult  Photoperiod (+ rainfall, temperature, social cues  Definition: Replacement of old integument w/ new like male density) = proximate factor (trigger) for timing of breeding integument o Replacement of feathers  Local peak food abundance = ultimate o Sometimes replace rhamphotheca, scales of (evolutionary) factor controlling breeding season legs + feet (podotheca) o Peak food abundance varies across spp + o New feather growing underneath pushes geography o = variation in breeding times across spp out old feather  Sometimes changed as breeding approaches (=  Snow geese: chick growth coincides with grass feather change indicates reproductive status) growth flush  Feathers = important structure:  Eleonora’s falcon: breed in the fall in o Lightweight Mediterranean = passing of southward migrating songbirds o Can be coloured o Replaceable  Honey buzzard: rear nestlings in mid-summer  Feathers wear out when wasp larvae most abundant  Worn feathers can’t be repaired, have to b replaced  Great tits: breed in early spring in oak forest so can feed chicks on herbivore caterpillars  Replacing feather = need lots of energy, need to fit  Atlantic puffins: nesting coincides w/ first-year into annual cycle  Can’t breed and moult or migrate and molt at same herring abundance time Phenological mismatch  Breeding = energy-intensive = need to fine-tune Simple Moult breeding time  Most songbirds do complete molt  Replace all feathers (flight + body feathers)  EX: Blue Tit in Europe vs Mediterranean islands  Wing feathers replaced sequentially (one feather o Insectivores per wing) o Woodland (deciduous + evergreen forest) o = can still fly  Peak food abundance earlier in deciduous than evergreen  Comes after breeding  Takes several weeks  = different egg laying dates  Sometimes have second mold o Difference in breeding onset = genetic o After first complete molt o Birds from deciduous that invaded pine forest plantation (young birds) still have o Partial molt o Change appearance for breeding season early breeding onset = maladaptive o Just replace body feathers in a few regions o Energetic consequence of food mismatch o EX: Goldfinch:  Expend more energy looking for food  Post-breeding complete molt makes  Consequences of mismatch: males + females similar in plumage + beak colour o Lower adult survival  Pre-breeding partial molt replaces o Slower chick growth body plumage = get sexual o Fewer second clutches dimorphism  = strong selection pressure on timing + breeding in most species  Also change in beak colour (dark in winter, yellow in spring)  Dark colour b/c melanin Breeding date + climate change deposition during post-  Climate change = spring arriving earlier nuptial moult o = temperature-dependent phenology (leaf bud burst, insect activity) shifted earlier  Yellow b/c lose melanin + deposit carotene in beak o = timing of peak prey abundance changes  Melanin loss/deposition  Affects reproductive success controlled by testosterone o Pied Flycatchers have mismatch btwn peak caterpillar abundance + nestling growth Simultaneous molt – Waterfowl  Loons, grebes, waterfowl, rails, alcids moult Timing of molt in migratory species primaries simultaneously  Migratory spp (esp. long-distance) have to fit  = can’t fly for few weeks around breeding season + migrations  Mute swans flightless for 40+ days during flight  Most migratory spp do complete molt in late feather molt b/c have to regrow 30 cm long summer after breeding, then migrate south primaries  Take advantage of high food abundance at end of  Can continue to forage w/o flying, but stay on breeding season for energy-costly molt water/close to water away from predators  Long-distance migrants (i.e. arctic) switch  Male mallards: hemispheres = go from high food abundance on o Have post-breeding (post-nuptial) molt in breeding grounds to high food abundance on late summer after wing feather replacement winter grounds  Get cryptic female-like plumage  Shorebirds don’t have time to complete molt at end  Helps them hide in marsh during of short breeding season flightless period o Compromise flight efficiency and travel o After complete molt, have partial pre- south with worn wing feathers breeding (pre-nuptial molt) to regain bright o Have winter molt (molt after southward breeding plumage (but don’t molt flight migration) feathers)  Pre-breeding occurs in winter b/c Migration mallards keep doing courtship +  Every year 50 billion birds (half of all avian pairing in winter and nest in early species) migrate spring  Fatten up before migration o Females have prenuptial moult later in  Fly non-stop for hours early spring  Use magnetic field/stars to navigate Complex (incomplete molts) Definitions  Albatrosses, vultures, eagles, pelicans, herons  Seasonal migration: 2-way mvt btwn (summer)  Large birds that have to continue flying during regions + non-breeding (winter) regions molt period  Evolved in response to annual seasonality  Need long time to complete molt o = can exploit food resources in diff regions  Molt done in spurts @ diff times of annual cycle  Depends on timing of breeding + migration  Not all birds migratory  = birds have mix of fresh feathers + old worn o Half sedentary feathers  Migration ≠ dispersal (dispersal = one-way,  EX: Laysan albatross: random direction → juvenile birds) o Mating, incubation, rearing of single chick o Dispersal can result in range expansion (= takes 260 days o Then migrate north for 100 days to winter spp increase breeding range by disp from home range) o During 100 days, undergo complex molt feathers Seasonal Migration o Complete wing molt takes 200 days so molt  2 types: a few feathers at a time o Short-distance (summer + winter grounds o Then breed after returning to breeding geographically close) grounds  Could be local o If fail to breed, will try to fit in complete  Also have altitudinal migrations molt before next breeding season begins (<10 km) o Example of how breeding + molting o Long-distance (transcontinental latitudinal incompatible shifts btwn summer + winter grounds)  Tradeoff between molting + not  > 2500 km breeding  Or partial molt and retain worn Migration Routes feathers (reduced flight efficiency)  Flyaway = geographical area covered by bird (=  Egg-laying for several days (one egg laid per da) breeding + non-breeding grounds + migration  Female incubates eggs for 12 days route)  Chicks are altricial w/ some natal down  Male helps female feed chicks Migration Stopovers  Rapid chick development (by 2 weeks, can fly a  Stopover sites = migrants rest + refuel en-route bit)  Most migrants have skip-hop strategy (stop at key  Parents keep feeding fledglings for another 2 days feeding sites along way)  Some migrants have non-stop flights (no  Have feather molts as chicks grow stopovers)  Then have post-breeding molt o Bar-tailed Godwit  Chicks start with natal down feathers o These moulted into juvenile plumage Components of Migration o Juveniles molt again (prebasic molt) =  Not just flying from A to B immature plumage they keep for winter  Migratory birds change morphology + behaviour o Then migrate south with parents before + after migration o (adults have complete post-breeding molt  Pre-migration: before migration = flight + body feathers) o Birds get restless (increase feeding = o In late winter, juveniles get adult plumage hyperphagia)  = add fat stores LECTURE 7 – SONG  Increase size of light muscles Introduction  Digestive organs enlarge to accommodate hyperphagia but  Bird sounds for communication: regress b/fr migration o Song o Vibrate individual wing feathers  Keep wing loading down o Drumming o Increase nocturnal activity (b/c migration occurs at night) o Clap bills, wings  Long-distance arctic breeding migrants have to arrive on breeding grounds w/ enough fat + protein Songs and calls  Produced from the syrinx stores to mature eggs  Sounds modulated by trachea, throat, larynx, o When they arrive, is still cold, food scarce o Nesting has to start within 10 days of tongue beak arrival, or not enough time to raise chicks  Songs differentiated from calls: Song Call Case Study: White-crowned Sparrow Life Cycle - Complex - Simpler  Breeding season, migration (fall + spring), pre- migratory fattening, 2 annual molts, wintering - Learned - Innate period - Usually produced by - Males and females  Breeding = territory establishment + defense, males (courtship) - Not only for - Diurnal rhythm courtship (mostly for female attraction, courtship, pairing, nest building, (mostly in morning + survival, alarm, egg laying, raising, fledgling young dusk) contact, flight)  (sedentary species has simpler life cycle: post- breeding molt, winter fattening, pre-breeding molt, - Species-specific gonadal maturation, breeding) Song Structure  Spectrograph/sonograph = graph sound in  WCS breeds in Hudson Bay lowlands frequency-time plot  Males arrive before females: o Establish territories (feeding areas)  Oscillogram shows amplitude vs time o Attract females  Sonograph shows frequency vs time o Traces intensity of sound  Pair formation when females arrive o Can use to visualize structure of song  Females accumulate calcium from environment, build fat  Structures:  Nest building by female alone (5 days) o Notes (elements) – cts sound trace o Syllables (basic unit = 2+ notes combined into repeatable unit) 2. Motor skill phase o Phrases (distinct section of song = motif)  In first spring, sparrows start singing  Songs not perfect o Song (group of phrases) o Repertoire (song types = group of song  Sing, then compare it against their memory types within individual)  = Auditory feedback until get good match o Dialect (population of song-types distinct  3 stages of normal song development: o Sub-song from another population of song types)  Syllables = basic units of bird song o Plastic song  Geographic variation in composition of song types o Crystallized song among individuals in population  Have to fine tune songs each spring (= short plastic o = dialect period every year) Mozart’s starling Bird Song and the Brain  Starling = mimic  Bird songs stored/produced in brain  Also Mockingbird, Lyrebird  4 major song nuclei in avian forebrain:  But copy sounds that aren’t species-specific 1. HVC (Higher Vocal Center) o Learn sounds from other species 2. LMAN (lateral magnocellular nucleus) o Can learn new songs throughout life 3. RA (robust nucleus of arcopallium) o = vocal learners 4. Area X  Nuclei connected in vocal motor pathway + vocal learning pathway Song Learning  Songbirds have avian song nuclei  Vocal learning rare:  Non-learners (EX: phoebe) doesn’t have song o Humans, bats, cetaceans, mammals, birds  Vocal learning from 3 groups only in birds: nuclei o Songbirds (oscines)  Song system depends on hormones  Songs sexually dimorphic o Hummingbirds  Both sexes memorize species-specific song, but o Parrots only males produce song  White-crowned sparrows that were deaf and couldn’t hear themselves sing developed funky  HVC in male canaries 3X bigger than females  Song is seasonal: songs but still species-specific o = song system changes in size (influenced  Birds do have in-built crude song template by testosterone)  In acoustic isolation, but with hearing, still develop o HVC grows in size for breeding season songs, but not well formed  Isolates allowed to hear songs from other isolates o = reflects increase in neuron number  Canaries = open-ended vocal learners better (still imperfect) o Can acquire new songs each year  Isolates that hear normal song (taped adult song) o Adult neurogenesis (new neurons added to during sensitive period have normal songs  Sensitive period = limited period of time during avian song system) which song learning happens o = brain cells replaced Birds and humans Two Step Model of Song Learning 1. Memorization phase (sensitive phase)  Birds closest to humans in terms of vocal learning  Birds young, can memorize/learn songs  Use bird song as model of language acquisition  Copy songs of own species (can filter out songs of  Birds + humans have specialized forebrain areas other species) dedicated to learning vocal communication  Both have syntax (rules for arranging syllables)  For WCS, distinctive whistle = key cue for young birds o Human speech has more complex syntax o Don’t copy songs that don’t have this  Have sensitive period, auditory feedback, motor feature phase (perfect song through repetition)  Adults don’t sing until spring so no chance to hear o Subsong of birds similar to babies babbling songs again after spring Song Function  = Potential future threat (not immediate danger)  Most song = males in breeding season:  But evict danger to prevent future problems  Mobbing call = noisy broad-band call repeated 1. Territoriality 2. Courtship  Easy to localize + conspicuous  Attracts other songbirds to location Experimental tests of song function in territoriality  Fly at the predator, harass it  Test functionality of song in territorial context o Muting, song playbacks, speakers LECTURE 8 – COURTSHIP  8 territories w/ speakers expt: Introduction o Re-invasion slower in experimental  Courtship functions: territories o = song function maintains territory o Attract mate o Stimulate + synchronize receptivity o Convey info about potential mate: Bird Calls  Sex of individual  ½ of all birds sing  All birds (except storks + vultures that use bill-  State of readiness  Size clapping) vocalize as calls:  Experience o Contact, alarm, courtship, flight  Quality  Calls made by all age classes:  Courtship displays usually acoustic or visual o Chicks in eggs  Male sends signal to female to induce her to mate o Nestlings  Female chooses who to mate with  In spp with polygamous mating system usually Alarm Calls have sexual dimorphism (esp. in plumage)  Call to warn conspecifics about danger  Info about potential threats Acoustic and visual displays Why Alarm calls?  Song used in courtship 1. Kin selection: o Mate recognition o Caller at higher risk of detection but if calls o Male quality indicator alert + save relatives, then shared genes  Also other noises: survive 2. Bird is selfish o Mechanical/drumming sounds o Woodpecker, tapping stick on wood o If bird sees flying predator, might no be o Move feathers really fast safe for it alone to fly away to cover b/c  Nuptial gifts predator might see it o If alarm and make other birds take cover, o More in birds where parental care shared  Visual displays could enhance own survival w/ dilution o Postures, plumage effect o Prevalent in polygamous species Freeze (seeet)  When songbird spots flying predator gives seet alarm call Example: Visual displays in Birds of Paradise  Other songbirds seek cover, freeze  BOP elaborate plumage ornamentation  Males gather at display trees:  Acoustic properties of call special: o Call + display plumes o Narrowband pure tone + high frequency o Also elaborate courtship dances in o Sound doesn’t travel far, not heard by predator courtship arena (Carola’s Parotia)  Bowerbirds o Hard to localize sound (cryptic) o Build + decorate structures in display o Just given once, so hard to localize courts  Woodland songbirds in EU + NA converged to this type of alarm for flying predators o Males spend 80% of time building bowers o Don’t help with parental care o Structure only for courtship but male Mobbing call spends a lot of time on it  Given when stationary predator o 2 types of bowers: 1. Maypole-bower builder: 1. Polygny (one male mates with > 1 female) o Weave sticks around thin tree 2. Polyandry (one female with > 1 male, rare) o Decorate o Spotted Sandpipers o Circular display court at the base  In polygamous mating system have marked sexual o Creates maypole by sticking twigs around dimorphism sapling tree o Hang decorations on twigs (dead insects + Female Choice  Female choice = intersexual selection fruit)  Dominant form of sexual selection in birds: o At bottom, creates circular court lined with moss + lichens o More important than male-male o Courtship: Chasing around the maypole in competition (intrasexual selection) game of “peek-a-boo” o EX: Fighting:  Get selection on traits useful for 2. Avenue-bower builder: o Bowers = free-standing stick walls on fighting either side of avenue o Male Satin bowerbirds decorate: Widowbird tail length + sexual selection  Smear fruit pulp on walls  Sexual dimorphism: Males long tail  Polygynous:  Coloured objects o Male territories have many nests o Visiting female enter bower and watch as male calls + fluff feathers in courtship  Possible to have many females breeding in same area b/c high seed biomass in habitat so enough food Sexual Selection Experiment:  Sexual selection might outweigh cost of higher predation + reduced long-term survival  Evidence for female choice on male tail length to  Sexual selection according to Darwin: explain sexual dimorphism? o Advantage of certain individuals over other o Have variation among males in mating success (# of resident females on territory) individuals of same sex + species b/c of correlated w/ male tail length reproduction  Ingredients:  But maybe females choose males based on o Differential mating success correlated trait?  Experimentally manipulate tail length in males  = intraspecific reproductive  Observe how many females each male got competition  Males w/ enhanced tails got more females  = female selection on males Anisogamy Peafowl/Peacock + female choice  Difference in gamete size between eggs + sperm  Lek system (polygamous mating system)  Males don’t hold territories:  Males invest less energy + time in sperm o Gather at sites to display  Females invest a lot of energy in eggs
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