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155 Cards in this Set
- Front
- Back
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Can nonmigratory birds shift their range? |
Yes e.g. Northern mockingbird 16 of 22 passerine species had a northward shift of median 100 km |
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Can great tits adjust their timing in response to climate change? |
-Average egg-laying date is 2 weeks earlier than in 1960s -Shift in egg-laying date tracks increase in spring temperatures -"Warmth sum" is the cumulative daily temperature (i.e. add all days together) over the spring period |
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Does an earlier first egg date evolve via gradual natural selection on a genetic trait or through phenotypic plasticity? |
If so, this requires a change in gene frequency over many generations: such that more individuals today have genes for early egg-laying Or is it phenotypic plasticity of individuals? If so, the observed population-level shift could occur rapidly if most females are simply changing their behaviour |
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How long do Charmantier and Gienapp 2013 predict it would take for natural selection to evolve a 2 week shift in egg lay date? |
-2 centuries: 100 years per week! |
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Can long-distance migratory birds shift their range? |
-NO: Earlier springs and peak food but arrival date doesn't change |
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What happens when there is a mismatch in timing of migration? |
Population decline |
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Did purple martins get any temperature cues in 2012 different from 2011 to cause a change in migration timing? |
-No cues, temperature not higher during passage |
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Were wood thrushes flexible with migration timing? |
no, low variation in spring timing Departure explains 71% of variation in arrival date -They depart on almost the same day year to year |
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What evidence is there that timing is constrained at the genetic level? |
Circadian rhythm genes control timing: More repeats in poly Q region of Clock bred later Low polymorphism in Clock could constrain adaptation to climate change |
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How many distinct anatomical features are shared by birds and theropods? |
Over 100 |
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What are the features of modern birds? |
-Reduced bones in hands and wrist, fused bones in hand, feet, pelvis, and skull. -Furcula, keeled sternum, uncinate processes on ribs -Toothless beak -Pygostyle, lightweight skeleton and hollow bones -Asymmetrical flight feathers |
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What is the keel? |
Where the flight muscles attach - indicative of powerful flapping flight |
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What are the reptilian features of birds? |
-Hard "sclerotic ring" supports eye -Lower jaw made of several bones -Single occipital condyle and middle ear bone -Enlarged lateral braincase -Scales -Red blood cells are nucleated |
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Contrast reptile and bird features |
Reptiles: Teeth on jaws, separate hand bones, separate pelvic bones, long tail with many bones, small, cartilaginous, sternum, simple ribs Birds: No teeth, fused hand bones, fused pelvic bones, fused pygostyle, sternum is large and keeled, uncinate processes on ribs, feathers, bills, gizzard |
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What is the "missing link" between reptiles and birds? |
Archaeopteryx |
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What is Archaeopteryx? |
-Crow-sized "bird" with feathers and wings 150 mya -Capable of flight (asymmetrical feathers) -Pectoral muscles not well enough developed for sustained rapid flight -Had to take off by running or by jumping off elevated perch |
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What are the similarities of Archaeopteryx to birds? |
-Enlarged lateral braincase -Reduced digits with fused bones -Fused pelvis |
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What are the differences of Archaeopteryx to birds? |
-No pygostyle: Archaeopteryx had a long bony tail -No enlarged keel in Archaeopteryx -Uncinate processes not pronounced in Archaeopteryx |
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What is the relation of symmetry to flight in feathers? |
-Symmetrical feathers don't fly: tail feathers. Used for steering and braking, not an airfoil -Asymmetrical: leading edge of each feather is thin and stiff to withstand the thrust force of flight; each feather acts as an airfoil |
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What kind of feathers did dinosaurs have? |
Range from: Dinofuzz: Short, simple filaments with no shaft on dinosaurs More complex feathers with a stiff central shaft and lateral barbs -Most did not have asymmetrical feathers |
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When and where were feathered dinosaur fossils first found? |
China in 1990s |
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What could feathers have been used for in dinosaurs? |
-Thermoregulation, balance, displays |
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What is the microraptor? |
-A 4-winged flying dinosaur from 120 mya -Long feathers with hooked, interlocking barbs on the hand and leg were asymmetrical -Feathers on the rest of the forewing and hind leg were symmetrical -Broad airfoil surfaces suggests very efficient gliding |
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What are the two positions for how microraptors flew? |
1. Legs splayed sideways: Leg feathers trail behind leg so the leading feathers do not cut into air -Leg primaries point backward -Why are leg primaries asymmetrical if they are not on the leading edge during flight? 2. Legs underneath: All theropods hold legs underneath -Leading edge of leg primaries now face forward, which explains why they would be asymmetrical |
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What are the 3 key features of modern birds that first arose in the Mesozoic? |
1) Pygostyle 2) Pronounced keel 3) Tooth loss |
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What is the Confuciusornis? |
-Ancient bird with reduction of tail to pygostyle -Tail function (balance, steering) was accomplished by long tail feathers -Clawed fingers, small keel, pygostyle tail (longer than modern birds) -No teeth like modern birds |
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What is the Zhongjianornis? |
-Found in early Cretaceous deposits in NE China -122 MYA -Lacks teeth, has a pygostyle -Poor flier: no keel on sternum -Clawed wings |
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What is the Sinornis? |
-Diverse group of birds called Enantiornithes -Wings resembled modern birds but most had claws and teeth -Sinornis is a good example: sparrow-sized bird, many modern bird features: reduced and fused digits, furcula, keeled sternum, fused pelvis and pygostyle |
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When did birds lose their teeth? |
116 million years ago |
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What could the toothless beak be useful for? |
In flying birds: lighter than with teeth -Zhongjianornis ate seeds and toothless beak may have functioned as grinding up seeds |
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What features of birds help flight but did not evolve for flight? |
-Feathers, but flight using feathered wings arose independently several times -Reduction of teeth for seed-eating |
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How did birds fare at the end of the Cretaceous? |
-Fossils show high bird diversity late in Cretaceous but only a few lineages survived the mass extinction |
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Which bird groups did all modern birds evolve from? |
-Tinamous -Gallus (Pheasants, chickens) -Anas (Ducks) |
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What were the terror birds? |
-Large carnivorous birds from Paleocene -Dominant predator in south america and common until recently -Went extinct when land bridge to North America formed (new apex predators moved in) |
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What are the hypotheses for evolution of wings? |
1) Wings evolved from arms to catch small prey 2) Wings used as sexual display structures 3) Wings evolved to assist bipedal leaping 4) Wings evolved from gliders who began to flap (arboreal) |
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What is the arboreal theory? |
-Flight evolved from gliding and flapping from elevated perches
-Many dinosaurs and pre-dinosaurs were arboreal, and some also flew |
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What is the evidence for arboreal theory? |
-"Cheap energy provided by gravity" -Many current examples of jumping-gliding animals -Small size + high places = origins of flight |
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What is the Cursorial theory? |
-Also called 'running' theory -Begins with theropods -Extension of limbs favoured jumping/leaping thus enhanced hunting abilities |
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What was Ken Dial's ideas for how wings were adaptive before flight? |
Tested birds walking up surfaces of various incline angles, found that wing falpping assisted climbing -used to escape predators and find food |
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Why were Archaeopteryx's feathers bad for flying? |
-Pre-evolution of hollow feathers, feathers too weak to sustain anything but weak flight, not flapping flight |
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How does an individual start flying? |
-Lift off is the most energetically costly part -Need to generate lift via airflow over wings -Once airborne, flight is highly efficient and some species can stay aloft for hours, days, even months |
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Which muscles are used for flight? |
-Supracoracoideus used for upstroke: tendon acts like a pulley to pull the wing up -Pectoralis used for downstroke: heavy flight muscles close to the center of gravity |
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How is lift created on a bird's wings? |
-Bird wings are curved to create an airfoil -Air flows more slowly under the wing because it is compressed, creating high pressure and lift -Air flows faster above the wing, creating low pressure -Air going over upper surface gets to the trailing edge before air underneath = lift |
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What is the Angle of Attack and how does it influence flight? |
-Angle of trailing edge of wing towards leading edge, affects degree of lift -The greater the angle, the more lift until the air breaks from surface, causing stalling -Near-vertical angles cause stalling and is used to brake when landing |
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How do birds land? |
-Make the angle of attack steep, which causes severe drag and poor lift -Raise the alula to redirect air over the wing which prevents stalling and reduces lift |
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What is the alula? |
A modified wing that helps prevent stalling at slow speeds -Found on 155 mya fossil -Eoalulavis hoyasi : name means 'dawn of the alula' -Found in former freshwater lake, may have hunted in shallows |
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Did the Archaeopteryx have an alula? |
-Probably flapped and glided but did not have an alula -Alula is the 'finale' in the evolution of powered flight |
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How is thrust provided in bird flight? |
-Forward movement of wing during downstroke; net force on wing is at right angles to surface -Secondaries are held relatively level during flight to provide lift -Flexible wrists allow primaries to move differently -Primaries provide forward and downward thrust during downward stroke |
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How do geese fly? |
-Have to run on water surface -Wrist and primary feathers act as a propellor for thrust -At take off, wing tips are thrust far forward and down to create lift and forward motion -Once aloft and moving fast, the wrist and wing tip movement is less extreme |
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How do hummingbirds fly? |
-Hovering: allows the bird to remain stationary and involves a "figure 8" movement of the wing that provides lift on both the up and downstroke -Hummingbirds can fly backwards and even upside down (for short periods of time) |
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How was it determined if swifts ever stop flying during winter? |
-Attached accelerometers (movement and angle) and geolocator light-loggers (location) -Measure activity during day and night -Measure "pitch" (horizontal = flying) -Wintering swifts most active around sunrise and sunset, but no stationary period -If they sleep, it must be during flight |
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What do different shapes and sizes of wings allow birds to do? |
-Aerial/open-country species usually have long pointed wings for high speed -Short rounded wings give more manoeuverability in dense vegetation -Migrants usually have more pointed wings than resident relatives |
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What is the aspect ratio of a wing and what does it indicate? |
-The length to width -Elliptical or 'rapid takeoff' wings = low AR -high lift wings have low aspect ratios -High speed/soaring wings = high AR |
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What are slots, or winglets? |
-Extra feathers at the ends of wings to reduce drag at wing-tip, reduce stalling speed |
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What is wing loading? |
-Weight of bird divided by wing area -Low WL = less power needed |
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What differences do wing loading and aspect ratio have on cost of flight? |
-Long wings and high ARs = low WL = inexpensive flight -Low AR of many birds that occupy dense vegetation = expensive flight = more walking -Birds with higher WL, e.g. penguins, are flightless |
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How are bird lungs different from mammals? |
-Bird lungs are small, compact, netowrks of tubes: not large collapsible bags -Weigh as much but use less space -Most of lung is not capable of gas exchange -Trachea branches into 2 bronchi which pass through lungs, directly to posterior air sacs |
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How do the air sacs help birds? |
-9 air sacs, thin to allow continuous unidirectional flow of air through lungs -Sacs store and shunt air prior to, and after leaving the lungs -Helps remove heat and cushion organs |
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How does the bird's lung help breathing in flight? |
-Birds replace most air with each breath = more oxygen -Birds have no diaphragm, lower sternum and expand ribs, aided by furcula -Wing-beat cycles correspond with breathing cycles = reduced cost |
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How does the air cycle through a bird's lungs? |
-Inhalation expands posterior (new air) and anterior (old air) air sacs, and new air passes through lungs -Exhalation contracts air sacs and new air passes through lungs -Two cycles of inhale/exhale needed to move a single parcel of air through lungs and back out mouth |
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What is the Harmonic mean thickness? |
-Thickness of barrier that affects diffusion of oxygen from air capillaries into blood capillaries -Birds have relatively thin barriers compared to bats and non-flying mammals |
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Why did dinosaurs also have air sacs and how did they work? |
-Adaptation for higher metabolic rate? (dinosaurs warm-blooded?) -Oxygen levels 175-275 mya half of today's 21% -Adaptation for low oxygen, not flight? |
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What is the relation of hollow bones and air sacs? |
-Air sacs expanded into hollow bones -Pneumatic foramen are holes in the vertebrae that allow penetration by the air sacs -Hollow bones not only reduce weight but play a key role in efficient respiration |
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How is the bird's heart similar and different to mammals? |
-Large and 4-chambered -Larger than mammals (relative to size and mass, 41% larger) -Have highest blood pressure in vertebrates -Heart of humans is 0.4% of body weight and averages 72 beats/min, house sparrows are 1.7% and 260 bpm, RTHU is 2.4% and 615 bpm |
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How is a bird's metabolism different from mammals? |
-Slightly higher basal metabolic rate compared with mammals of same size -Slightly higher body temperatures -Heart rate depends on body size, most birds around 200 beats/minute when at rest |
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How much time do birds spent at basal metabolism? |
-Not much, just being awake raises metabolic rate by 25-80% -Small birds in flight at 10-25X basal metabolic rate for many hours (sustained for long periods) |
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How long does the blackpoll warbler's migration take? |
-Up to 88 hours. 2500 to 3500 km over ocean |
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What is the normal body temperature of birds? |
-They are endothermic, 40-44 degrees Celsius, > mammal |
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What do increases of temperature and metabolic demands do to birds and require? |
-Increase temperature = increased rates of physiological processes eg. nerve conduction, muscle fiber contraction -Increase in metabolic demands requires very efficient respiratory and circulatory systems |
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What temperature regulation features do birds have? |
-More feathers and more fat
-Insulation depends on amount of plumage, can increase 70% summer to winter -Sparrows increase plumage weight 0.9g to 1.5g autumn Feather set important; birds can adjust angle of feathers to increase/reduce convective heat loss -Colour important: black absorbs, white reflects |
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What is Bergmann's rule? |
-Body size of non-migrants reflects climate -Size varies inversely with temperature: consequence of SA:V relationship -Latitudinal or altitudinal gradient in body size |
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How are house sparrows an example of Bergmann's rule? |
-Adapted within 100 years to new range -larger birds survive winter better -Better at thermoregulation in cold and better fasting abilities -Body size depends on seasonality and temperature range in both North America and Europe |
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What are behavioural adaptations to temperature regulation? |
-Wind speed increases convective/advective cooling: so birds seek still places in cold weather -Heat loss depends on wind speed: at 27 km/h cooling effect is 3x the value in still air -Northern species start to shiver at 7-9 degrees celsius, southern at 18 degrees -LCT higher in small birds = more sensitive to cold |
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Does it cost more to keep cool or keep warm? |
-More to keep cool |
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What is hypothermia? |
When body temperature is below normal -BCCH drop body temperatures 8-12 degrees at night in winter -high SA:V |
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What is torpor? |
-Profound hypothermia -Mountain hummingbirds can drop 10 degrees to reduce oxygen use by 75% -May take >1 hour to warm up |
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What is the Common Poorwill? |
-Hibernates at body temperature 5-6 degrees for 2-3 months in SW US and Mexico deserts -Reduces oxygen use by >90% -Hopi people called it "the sleeping one" |
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What are other methods that birds use to lose heat? |
-Pant to lose heat through mouth -Ruffle feathers to allow heat loss -Shunt blood into feet for cooling -Radiate heat through beaks |
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How much heat do beak radiators lose through their beaks? |
-At high temps, proportion of all heat loss taht occurs through bill averages 60% for adults -Juveniles have proportionally smaller bills so heat loss efficiency is 40% |
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Why is most of a bird's energy expenditure during migration while it is stopped? |
-Costs of staying warm at night and day feeding -High maintenance costs and long periods on the ground (especially in cool weather) |
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Why don't birds get dehydrated while flying? |
-Respiratory water loss is high, but birds lose protein and fat, protein catabolism generates 5x more water than fat metabolism -Discovered by flying Swainson's thrushes in a wind tunnel under high vs. low humidity -Found more lean mass loss (but not fat loss) under dry conditions) |
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Why do birds fly in a V formation? |
-One theory is that lead birds are more experienced navigators -Another is that there are energetic advantages, due to upwash from bird in front -Determined by putting heart rate monitors and cameras on pelicans and recorded wing beat frequency -Flying alone required higher heartbeat and wingbeat than in rear of formation -Total energy savings about 10-15% compared with lead or alone |
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What did bald ibises show about wingbeat timing? |
-Birds in a V formation synchronize wingbeats with the one in front so wingtips are in the region of maximal upwash when wings are raised and lowered -Sometimes flew directly behind, but then flew out of phase to maximally separate the path of the wing tips: reduces negative effects of downwash |
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Describe the Tyrannidae |
-New world family -Largest family in world (~400 species) -Primarily insect-eaters that seek prey from a perch and dart out and capture the target (sallying) -Perch in erect stance -Like most salliers, have rictal bristles |
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Describe the Laniidae |
-Shrikes, passerines that occupy a raptorial niche -More horizontal stance, commonly grayish -Not strongly taloned, but a ripping beak -Declining worldwide |
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Describe the Vireonidae |
-Vireos, New World Family of "foliage-gleaning" insectivores -Like wood warblers but slower, with slightly hooked beak -Mostly small and greenish |
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Describe the Corvidae |
Crows and jays, Cosmopolitan -Corvus is a genus of mostly black, intelligent species (tool use, problem solving, social communication, self-recognition) -Jays tend to be more colourful -Some food storage specialists -Little difference between sexes in colours |
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Describe the Alaudidae |
-Old World Family with one New World species -Horned Lark -Open country species that ground-forages -Long claw on hallux |
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Describe the Hirundinidae |
-Swallows, aerial insectivores -Known as "hawkers" rather than "salliers", they seek and capture prey on the wing -Superficially similar to swifts |
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Describe the Paridae |
-Titmice, small, mostly non-migratory species -Eat seeds and arthropods -Mostly woodland foragers -Chickadees have distinctive faces of black or brown and white patterning -Cavity nesters -BCCH have a phenomenal spatial memory |
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-Describe the Sittidae |
-Nuthatches, small birds that mostly forage on branches and tree trunks -more exploratory and surface-feeding, unlike the woodpeckers (often upside-down) -No stiff tail to stabilize drumming, but long claws |
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Describe the Certhiidae |
Creepers, only 1 species in MB -Small, mostly brownish insectivores that creep along trunks and main branches probing for arthropod food -Often helical pattern -Stabilizing tail, long claws, curved beak |
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Describe the Troglodytidae |
-Wrens, New World Family mostly -Mostly small, brownish birds that occupy dense vegetation -A troglodyte is a cave-dweller -Typically short tail that is often erect |
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Describe the Regulidae |
-Kinglets, small northern hemisphere family of tiny birds -2 in Manitoba -Generally greenish with some head markings -Forage in trees with a strong affinity in most species for conifers |
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Describe the Polioptilidae |
A small New World family -Tiny birds (often gray-blue) with long tails -Insectivorous -One sometimes found in Manitoba |
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Describe the Turdidae |
Thrushes "Plump", medium sized songbirds -Often eat invertebrates during breeding and fruit during winter -Generally forage on ground when eating inverts -Generally a horizontal stance |
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Describe the Mimidae |
Thrashers and Allies: Mimids -New World family of medium-sized birds with long tails -Ground and foliage feeders, invertebrate and fruit eaters (like thrushes) -Includes the Mockingbird |
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Describe the Motacillidae |
Pipits Mostly old world, only 2 MB species -Difficult to identify between tundra and field species |
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Describe the Bombycillidae |
-Crested birds with sleek plumage and waxy tips on a number of wing feathers -Three species, 2 of which are in MB -Forage on fruit, glean caterpillars, and sally like flycatchers |
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Describe the Sturnidae |
Starlings, introduced -Old World family -Often mid-sized generalist omnivores -Several "synanthropes" |
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Describe the Parulidae |
-Wood warblers, MB's most diverse songbird family w/ 26 breeding species -Small, mostly colourful, mostly sexually dimorphic (plumage), foliage gleaners -Mostly arboreal -North American ones migrate, mostly to tropics |
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Describe the Thraupidae |
Tanagers, Large New World family, but may not actually be a family -Mostly tropical, arboreal species with colourful plumages -Eat insects and fruits -Only one breeding in MB |
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Describe the Cardinalidae |
-Cardinals and Buntings -Also may not be a family -Strong, conical beaks for challenging seeds -Sexually dimorphic plumages |
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Describe the Emberizidae |
Sparrows, large, cosmopolitan
-Commonly ground-feeding species with seed-eating beaks (insect-eating during breeding) -Most are types of sparrows |
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Describe the Icteridae |
Blackbirds, New World family of mostly medium-sized species -Rich tropical diversity, only 10 in MB -Commonly largely black, sometimes with iridescent or highly colourful plumage -Strong pointed beaks often -Polygyny is common (and increased dimorphism) |
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Describe the Fringillidae |
Finches, seed-eating with conical beaks -Similar morphology to buntings and sparrows |
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Describe the Passeridae |
-Weavers, introduced (House Sparrow) -Seed-eating beaks too -Some African species build tremendous colonial nests |
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What is the syrinx? |
-Structure which produces sounds -Songbirds have a highly complex syrinx and highly developed song control center in their brain to facilitate song learning and memory |
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What is the difference in the syrinx between sub-oscine passerines and more recent oscine passerines? |
Sub-oscine paserines have a tracheal syrnix with few muscles -Oscine passerines have the syrinx at the junction of the trachea and bronchi with a complex set of muscles -can make sound on both sides |
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How are both sides of the syrinx controlled in oscine passerines? |
Interior: Internal tympaniform membrane is tightened and internal labium protrudes Exterior: External tympaniform membranes are tightened and external labia on both sides protruded with syringeal muscles |
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How do cowbirds sing? |
-Very rapid 2 or 3 note clusters -By alternating sides, the cowbird can adjust the silent side of the syrinx to get ready to start that side's next note without a frequency slur betwen notes -A final high-pitched whistle is always sung on the right side |
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How is song production in the brain wired in non-songbirds? |
-Dorsomedial nucleus (DM) controls the syrinx and respiratory system w/ respect to song -In the forebrain Field L, for auditory input, is not wired to song production (DM) and there is no song learning |
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How is song production in the brain wired in songbirds? |
-Two critical pathways: Song production and song learning -HVC (High vocal center) is central to both pathways -HVC to RA (robust nucleus of arcopallium) to DM wiring triggers song production -Field L (auditory input) is wired to HVC so birds can adjust their song production according to what they hear |
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What is song crystallization?
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When young songbirds practice singing compared to what they heard from an adult model -In some species adults cannot continue to learn songs after crystallization |
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How is song production related to sexual selection? |
-Rapid broadband trills of "rivals" elicited more aggression from territory owners -Owners reacted more quickly, approached more closely, and sang more songs in response to rapid broadband playback -A male assesses his rivals based on their ability to sing difficult songs |
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How can sound made through feathers be sexually selected for? |
-Takes lots of energy to generate sound in flight -Sound quality depends on fine tuning |
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Why does multiple mating increase a male's fitness but not a female's fitness? |
-Males do not produce eggs or young, does not have time/energy costs of egg production |
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When is sexual selection stronger? |
In species with no pair bonds -usually more ornamented and have seemingly ridiculous courtship displays -The skew in male mating success determines the strength of sexual selection |
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How many birds are socially monogamous? |
90% |
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What is the "Lek" mating system? |
-Males have display sites to attract females for copulations. Skew in mating success very high -Occur where food is plentiful and predictable (and few predators) -Birds of Paradise: mainly fruit eaters, abundant, easy to exploit, so females can raise young alone |
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What is polygyny? |
-Males attract multiple mates by defending a large, high-quality territory through high aggression toward other males -Harem of females nests on males territory -Males with largest and best territories have highest mating success -Strong skew in male mating success = strong sexual selection |
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What environmental requirements are needed for polygyny? |
-Clumped resources -Abundant food -Most common in marsh-nesting species |
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When does monogamy occur? |
When there is a need for multiparental care |
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What are extra-pair copulations? |
Only 14% of socially monogamous birds are genetically monogamous -EPCs: copulations outside social pair bond -One average, >11% of chicks in broods may be extra-pair young -Leads to mate guarding: close association of male with female to ensure paternity, especially in early stages of nesting |
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What are the benefits of Extra-pair copulations for males and females? |
Males: Enhance reproductive success by siring more young Females: Enhanced quality of young in their nest |
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Can socially monogamous species still have skewed mating success? |
Yes, because of extra-pair copulations. Males who are attractive produce 4-8 young per year while unattractive males produce 2-4. -DNA testing showed that 30% of young in Hooded Warbler nests do not belong to the male that feeds them |
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What two ways can sexual selection occur? |
-Male-male competition -Female preference for certain males |
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How can you determine which traits are sexually selected? |
1) Show that male trait correlates with mating success 2) Do experimental manipulation of male trait to test if it does affect male mating success |
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When are female Superb blue fairy-wren's trips to neighbouring males most frequent? |
When female is fertile (several days before first egg) |
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What male traits do female superb blue fairy wrens prefer? |
-Males that molt into their bright plumage earlier in the year -Older males -Reason: moulting during dry season, early in the year is difficult and only best and most experienced males can do this |
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What male traits do female yellowthroats prefer? |
-Mask size of males -Experiment: female shown 2 males, one with large mask and one without, prefers large mask -Take two with equal mask and artificially increase mask size on one, female prefers it |
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What is cooperative breeding? |
-A breeding pair with 1 to as many as 6 helpers that may stay for more than a year |
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What are the benefits to helpers in cooperative breeding nests? |
-Enhance lifetime reproductive success through production of relatives: kin selection -May obtain help: reciprocal altruism -Helper may benefit by taking time to acquire skills |
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What are the benefit to parents in cooperative breeding nests? |
-Number of young fledged usually increases, helpers supply extra food -Added defence against predators, may raise adult survival -Helpers are often close relatives = kin selection -Parents must tolerate grown offspring on territory, trade-off with help received at nest |
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What are the ecological correlations for cooperative breeding occurring? |
-e.g. Pied kingfishers, Kenya -Lake Victoria: food is scarce, helpers double the number of young fledged -Lake Naivasha: food plentiful = few helpers = little difference in young fledged |
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What did the Seychelles Warblers show about cooperative breeding? |
-Space dependent -on small Cousin Island, no space: young helped parents in groups of up to 7 -Translocated to "empty" Aride Island: bred in territorial pairs until Island was "full", young became helpers again |
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What is polyandry? |
-Females with 2 or more males -Rare -Often associated with reversed sexual dimorphism (females larger, brighter) |
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Which orders have the sex roles reversed? |
-Found in 2 orders: Gruiformes and Charadriiformes |
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What is the mating system of the Vasa parrot? |
-Polygynandry -Nesting females become bald and head turns bright red -Females sing an elaborate and loud song from tree tops at a high rate -These songs attract males during incubation and nestling period; higher song rate = more males -Females highly aggressive toward each other |
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Why do Vasa parrot females compete intensely for males? |
-More males = more food = more offspring for female |
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What is polygynandry? |
-Different from polygyny or polyandry with individual males feeding at more than one nest -Characteristic of ratites and a few songbirds |
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How do Dunnocks mate? |
Polygynandry -Females solicit copulations from multiple males -Males mate with multiple females and place paternal effort where they receive the most mating -Experimental additions of food cause reduction in territory size and promotion of polygyny in Dunnocks |
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How do Bicknell's thrushes mate? |
-Evolved in harsh, stochastic montane environments where food is scarce and patchily distributed -Extra male help may increase RS -Polygynandry |
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Compare Altricial and Precocial young |
Altricial: naked, blind, immobile, cannot self-feed, cannot regulate body temp Precocial: downy, mobile, self-feeding, better temp. regulation |
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Compare eggs of altricial and precocial species |
Altricial: cheap eggs (20% yolk) and have short incubation, nestlings are still embryos when the egg hatches Precocial: expensive eggs with 40-50% yolk content, higher cost of egg production and longer incubation but chicks are relatively mature on hatching |
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Compare altricial and precocial chick growth |
Altricial: weigh 10% of adult body mass at hatching, but attain adult mass and fledge at 2 weeks of age Precocial: grow more slowly than altricial chicks because they feed themselves |
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What is the experiment to show how costly egg-laying is? |
Removed 1 egg from a lesser black-backed gull nest to force female to lay a 4th -Compare to control that only laid 3 -Females with 4 lost extra 5% body mass and more pectoral muscle |
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Do the costs of egg-laying affect incubation? |
-Experimental females reared 30% fewer chicks than control females and were 3 times as likely to fail at nesting -Experimental females also produced smaller fledglings: less likely to survive to adulthood |
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What is the cost of incubation? |
In many birds, only female incubates -Common Eider females incubate eggs alone and do not eat during 25 day incubation period -lose 20% of body mass |
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What did experiments on the cost of incubation show? |
-Manipulate clutch to produce 3-egg nests and 6-egg nests -Measure body mass and lymphocyte levels -Lower lymphocyte levels are indicative of immunosuppression and increased susceptibility to infections -Incubating 6-eggs was more costly |
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What negative carryover effects does high incubation demand have? |
-Later lay date -Smaller clutch size |
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What experiment showed the cost of feeding young? |
Kittiwakes with eggs removed from nest in late incubation reduced chick feeding effort to zero -Compared adult survival and future reproductive success with unmanipulated nests -Parents who fed young experienced lower fledging success the next year -High energetic cost of parental care has long-lasting effects on fitness |
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What experiment showed the cost of rearing young? |
-Studied jackdaws in nest box populations -Brood size increased or decreased by 2 -Some parents received same treatment for several years -Parents w/ enlarged broods had a 0.6 annual probability of survival compared with 0.72 for reduced brood parents -Difference far greater for those given enlarged broods in >2 years |
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What is senescence? |
Decreased annual probability of survival with increasing age
-Parents with enlarged broods in jackdaw experiment had faster rate of senescence |
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How do blue-headed vireos compete over parental care? |
-Males do 50% of nest building and incubation but abandoned by mates when young fledge -Male has to feed fledglings by himself for 2-3 weeks -Females make daily trips through forest to find bachelor male before abandoning family -On fledging day, females permanently move to the nest they had already built, lay eggs 4-5 days later |
