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VERTEBRATE ZOOLOGY (VZ Lecture26 – Spring 2012 Althoff - reference PJH Chapters 16-17) Birds – Part IV Bill Horn Wing Proportions • Over time (i.e., evolutionary time), major changes have taken place in the surface area present in bird wings: a) some large wings in proportion to body light wing loading vs. b) some small wings in proportion to body heavy wing loading • Also, wings may be long and pointed, short, or rounded • Also, wings can have high camber or be relatively flat • Also, width & degree of slotting can vary Powered flier vs. Soaring form • Type of flier reveals ____________ in length of various __________ of the wing: 1) hand 2) forearm 3) upper arm • Hummingbirds: very fast, powerful wing beats *longer hand bones > forearm + arm *mostly primaries, only 6-7 secondaries • ______ bird (marine species): powered flight AND soaring (lowest wing loading of any bird) • Albatross: extremely long wing, especially in upper arm: up to 32 secondaries Upper arm Fig. 17-11 p449, PJH forearm hand RELATIVE LENGTHS 4 Basic Structural & Functional Wing Types 1• __________________ – typical of seabirds like the albatrosses and shearwaters. Requires strong and persistent winds. Wings… A) long, narrow & relatively flat B) lack slots in outer primaries. -bird glides downward with increasing speed, and gains altitude when gliding into the wind -Also needs to be “vertical” wind gradient 4 Basic Structural & Functional Wing Types 2• __________ – typical of forest and woodland birds (pheasant, quail, ruffed grouse) where they must maneuver around obstructions. Low aspect ratio. Wings… A) tend to be highly cambered B) usually have a high degree of slotting in the outer primaries -typically, these species have rapid flapping but relatively slow flight. -Overall, good agility in “tight” places. 4 Basic Structural & Functional Wing Types 3• ___________________– typical of aerial foragers, those that make long migrations, or have a heavy wing loading that enables another aspect of their lives (like diving). Wings…. A) have flat profile (i.e., little camber) B) often lack slots in outer primaries -typically, associate with fast-flying birds, with wings usually in “swept-back” position 4 Basic Structural & Functional Wing Types 4• ___________ – typical of birds that exhibit “static” soaring type of flight. Vultures, eagles, many hawk species (broad-wings especially) storks, and other large birds. Wing has intermediate aspect ratio between the elliptical and the high aspect ratio wing design. Wings… A) have deep camber B) marked slotting on the primaries -these are birds known to “ride” the thermals -deep slotting permits slow flight yet high lift -individual feathers adjust to changes in currents rather than entire wing moved DYNAMIC SOARING HIGH ASPECT RATIO (shearwater) (swallow) 1 2 3 ELLIPTICAL HIGH LIFT (pheasant) (rough-legged hawk) Fig. 17-12 p449, PJH 4 Hind Limbs • Generally, the majority of bird species have two modes of locomotion a) bipedal walking or swimming with the hind limbs b) flying with the forelimbs • Terrestrial use of hind limbs: --walking, hopping, and perching • Modifications associated with quadrapeds are generally also associated with terrestrial bird designs 1) progressive ________ in length of distal portion relative to proximal toe 2) _________ in area of the foot surface touching ground 3) _________ in the number of toes Hind Limbs • No 5-toed birds • Generally, reduction in length and number of toes (especially the amount of surface area in contact with the ground) _____ what is present among most mammal species…but there is some. Example ostrich has 2 toes. And, many bird species have only 3 forward toes. 2 3 2 2 3 1 “Hoppers” • Moving forward, feet together • Only found in perching and/or arboreal birds…. • Highly developed in passerines (think goldenwinged warbler, Kirtland’s warbler, grasshopper sparrow,) a) some cannot walk—legs & feet cannot move independent of each other. b) some can walk & hop “Perching” • Does not require much energy • Tendons that flex the toe can lock the foot a tight grip—on rear side of ankle • No muscular contraction is required to hold the toes closed • Hobnail-like projections on tendons lying underneath the toe bones mesh with ridges on the inside sruface of the surrounding tendon sheath Toe arrangements 2 3 4 _______________ Syndactyl 2 & 3 fused 1 Pamprodactyl Zygodactyl Heterodactyl some ___________ BIRDS Webbed and Lobed Feet Partial webbing (3-toes) ducks Lobed Fig. 17-16 p454, PJH Totipalmate (4-toes) cormorants Power-strokeforward stroke (front) & side views Feeding & Digestion • Many specializations—especially with respect to beak & tongue designs • Beak designs include: insect catchers insect net fruit plucker generalized bill flesh tearer dip net fish grasper fish spear mud sifter water strainer seed cracker pine seed extractor Fig. 17-18 p456, PJH outward flexion • Skull ___________ possible in most birds • Influences feeding capabilities • Combination of inward and outward flexion results in _______ expanded in horizontal and vertical direction Fig. 17-19 p457, PJH Inward flexion outward flexion Inward flexion • For probing species, ability to raise the tip of the bill without opening the mouth provides opportunity to exploit food sources in the sand (some shorebirds) and/or soil (woodcock) • Woodcock shown here has beak that is 3+ inches long— probes for earthworms Fig. 17-19 p457, PJH American woodcock Woodpecker—probing tongue Anteater---probing tongue with different origin for tongue attachment (on sternum) but same result Fig. 17-20 p458, PJH NECTAR FEEDERS magnificent hummingbird green violet-ear hummingbird fiery-throated hummingbird volcano hummingbird • Note the __________ of the bill • Note the __________ of the bill food-straining (NORTHERN SHOVELER DUCK) fish-eater (sooty shearwater) Fringed, tubular nectar feeder (bananaquit) general feeder (robin) fruit-eater (Diard’s trogon) probing-spearing (woodpecker) fish-eater (sooty shearwater) fruit-eater (Diard’s trogon) food-straining (NORTHERN SHOVELER DUCK) fringed, tubular nectar feeder (bananaquit) Digestive System • • • • • • • • • • MAIN TRACT Oral cavity Pharynx Esophagus Crop (*) Proventriculus Gizzard Pylorus Small intestine Large intestine Cloaca AUXILLARY • Liver • Pancreas Earthworm small intestine anus mouth pharynx esophagus esophagus crop proventriculus small crop pylorus gizzard Small Gizzard Large and muscular Fig. 17-22 p460, PJH Starling (Sternus vulgaris) _____________ in diet length of intestine Fig. 17-23 p461, PJH Changes in Starling GI tract • Response to ______________ availability of certain food types • Higher plant content in diet (need more time to digest to extract nutrients) results in longer intestinal tract (~ _____ increase in length) • Besides anatomical changes, digestive enzyme composition changes, too, to different food types they consume: a) simple sugars in fruit vs. b) fat and protein in animal-based food Eye Anatomy Vitreous humor Fig. 17-25 p464, PJH • Birds have large eyes…so large that the brain is displaced dorsally and caudally • In some species the eyes meet in the midline of the skull • _______ structure here: the ______ the PECTEN • Shape varies from species-tospecies • Consist of blood capillaries surrounded by pigmented tissues and covered by a membrane but lacks muscles and nerves • Function: __________________ a) reduction of glare ? b) mirror to reflection objects above? c) visual reference point ? • May provide nutrition to retinal cells…& remove metabolic waste from vitreous humor Eye Shapes _____________ FLATTEN most falcons GLOBULAR owls & some eagles TUBULAR • The two to the right, especially the far right, won’t fit completely into the skull unless they were more of this tubular design (vs. flatten) Fig. 17-25 p464, PJH Cones vs. Rods • Rods and cones found in ____________ • Rods do _____ require much light to stimulate them vs. cones that require a considerable amount of light. • General trend, nocturnal species have considerably more rods than cones. Opposite trend for diurnal species (goes for mammals, too) • Humans: ~________ cones per mm2 • House sparrow: ~________ cones per mm2 • Common buzzard: ~________ cones per mm2 • RESULT extremely _____________ color vision! • Also, some birds can see near-ultraviolet wavelengths Hearing-related: skull asymmetry • Hearing sensitivity in birds appears to match, on average, that of humans despite smaller amount of structure/size of ears • This “equalling out” is achieved by a large tympanic membrane (TM) …and owls are “the” kings when it comes to the TM size relative to the skull. • Owls also have large cochlae and auditory center Fig. 17-26 p465, PJH Sense of Smell • In most species, very poorly developed • Olfactory capability reflected in the size of the olfactory bulbs and associated processing area in the brain • Noted exception: kiwi from New Zealand. A terrestrial bird has nostrils at the end of its long bill and uses that sense to locate earthworms underground • Turkey vultures follow airborne odors of carrion to the vicinity of a carcass…most of these scavenging species have featherless heads that reduce the risk not being able to ‘dry’ off the head or serve host to parasites Sense of Taste • Birds have few taste buds! Humans ~10,000 chicken ~ 24 (rear of tongue & pharynx) pigeon ~ 37 “ J. quail ~ 62 “ • Birds like chili peppers. Active ingredient in chili peppers are ___________. Have a “flaming” effect on the mammalian oral epithelia and taste buds. Normal concentrations repel rodents but birds do not find chili peppers distasteful. Birds actually attracted to them because of high vitamin, protein and lipid content. …any benefits to the pepper plant species?