WFC 111 (birds)

What this bird

Wood duck

What this bird

Tree swallow

Why care about birds

Most visible, widespread, abundant and diverse group

We relate to birds

• Terrestrial

• Diurnal

• Visually, oriented

• Highly mobile

What this bird

Cassowary

Economically important

• In 2022, 2.8 million people hunted migratory birds

• 38.7 million (home) and 17 million (travel) observed, photographed birds (~5 million in CA)

• 96 million “observed, fed, or  photographed” birds

• More than 1 in 4 Americans! (interact with birds)

• $43 billion spent hunting/wildlife watching

Conservation status of wild birds

• Globally, 13% species are threatened with extinction • An additional 20% are IUCN Near Threatened

• 150 species have gone extinct since the year 1500 (1,000- 10,000x background)

• Rapid declines in once-common species • Variation by guild and life histories

• Causes?

  • Agriculture (impacts 74% of threatened species)

  • Deforestation (50% of species)

  • Invasive species (39% of species)

  • Overexploitation – hunting and pet trade (33% of species)

What makes a bird a bird (generally)

• feathers

• beaks

• wings

• crazy feet

• hollow bones

• lay eggs

• bipedal

• some can fly

• generally small

• lots of variation though

Deep history

• In cambrian explosion most modern phyla came into existence

• Birds came in Pennsylvanian, here we have the last common ancestor of birds

• Synapsids (mammal precursor) evolved

Synapsids (mammal precursor) vs Diapsid skull

• Skull had lots of openings, one low temporal fenestra = give rise to mammals

• the diapsid skull had two fenestra a temporal and antorbital fenestra = give rise to reptiles and birds

Reptiles and birds – occipital condyles

• occipital condyles

• the part that connects the skull to the spine

• mammals have two

  • more finer movements but can’t turn head as far

• birds and reptiles have one (a single occipital condyles)

  • the single anchor point allows for more flexibility

Reptiles and birds – middle ear bones

• mammals have 3 ear bones

• birds and reptiles only have a single middle ear bone

Reptiles and birds – jaw bones

• Mammals have a single dentary bone

• In reptiles and birds there’s a fusion of multiple bones

Reptiles and birds – integument

• Integument is the otter most protective layer of an organism

• ex: scales, fur, feathers, tree bark

• In both reptiles and birds we have beta-keratin sheets for scales and feathers

• Mammals have alpha keratin spirals for har and horns

  • Remember birds have scales! Dinosaur feet

Feathers

• feathers are derived from scales

• modified scales

• feathers and scales have the same evolutionary origin

Reptiles and birds – nucleated red blood cells

• mammalian RBC is enucleated

• Reptile and birds RBC is nucleated

Reptiles and birds - ovipary

• both reptile and birds lay eggs!

• Reptiles tend to have a bit more of a leathery shell

• Birds have harder, mineralized shell

  • where do you get calcium for these eggs?

  • They eat lots of bugs before making eggs, to take calcium from bugs

Potential exam question, name 5 similarities between birds and reptiles

• Similarity in skull features

• Presence of antorbital fenestra

• Single occipital condyle

• Single middle ear bone

• Lower jaw composed of several fused bones

• Similarity in integument – scales and feathers

• Nucleated red blood cells

• Ovipary

Bird trait - feathers

• Basic parts

  • Rachis: strong middle shaft

  • Vanes

  • Calamus/quill: part of Rachis with no vein

  • Inferior umbilicus: the hole in the bottom of feather

Bird traits - teeth

• birds do not have teeth

  • teeth are heavy, birds ditched that

• Have bills instead of teeth

• different types of bills for different specializations

• All for weight reduction

Birds - walking

• birds are bipedal (bipedalism)

• Also Digitigrade

  • they walk on their toes

• Femur of bird is up inside the bird

• the ankle is like that joint way up where the legs bend

Traits of birds – fusion and reduction of bones of hands, head, pelvis

• lots of fusion in hand, jaw, pelvis area

• rigid structures do better in the area

  • an airplane isn’t wobbly

  • rigid stuff flies better

• birds don’t have support via fingers like humans or bats

• the rachis of birds provide the support that fingers would

bird - bones

• bird bones are hollow

• they have some solid bones, like in femur

• but most wing and lower leg bones are hollow

• they have these pockets in bones

• weight reduction and helps with avian respiratory system

• don’t give dogs bird bones, they splinter and are sharp

Bone density

• varies among birds

• a loon vs a hawk

  • the loon dives and swims, so it wants more solid bones because their lifestyle requires them to be under the water

Bird trait - well developed keel of breastbone

• Birds have very thick, keel breastbone

• Like birds, ships have keels, because it keeps them balanced

  • big structure with low weight means you’re not top heavy, so balanced

Traits of birds – furcula (wishbone)

• where the neck attaches is the wishbone

• fused collar bones

• allowed flight to become more possible

• our wishbone is just our collar bones

Potential exam question, what are the unique traits of birds (what makes birds different from reptiles)

• Feathers

• Lack of teeth; bills

• Bipedalism and digitigrade feet

• Fusion and reduction of bones of hands, head,

pelvis

• Pneumatic bones

• Well-developed keel of breastbone

• Furcula (wishbone)

Other general bird traits (some birds)

• Small sizes

• highly developed brains and sensory systems

• large, energy rich eggs

• extensive parental care

  • crocodiles and alligators, closest reptile relative to birds also put lots of parental care

• highly social

The Five Mass Extinctions

• end-Ordovician

• end-devonian

• end-permian

  • 90% of all species died

Preserved fossils

Silts, limestones provide some of the best substrates within a layer to detect fossils

• soft and holds fossils really well

In 1860 thy found a fossil feather on Solnhofen limestone formation

• rest of the fossils in this area contain fossils from the jurasic

In 1861 they unearthed the entire bird specimen

Archaeopteryx lithographica

• found it in 1861

• clearly has feathers

• clearly has wings

• found another one 3 years

  • held on display at an inn until the son of the physician and came to the inn and bought it from the inn keeper

• fully feathered

• the wing feathers were specialized into primaries and secondaries

• Clavicles fused into furcula

  • needed for flight

• partly fused metatarsals (leg bones)

• Bird-like forelimb

• feathers were asymmetrical

  • like modern feathers with a leading and trailing edge

Archaeopteryx lithographica reptile traits

• small braincase

  • modern birds have larger

• Hand bones not fully fused and had claws on its wing

• pelvic bones were not fused

  • still so wiggliness

  • could fly but probably not for long distances

• had a long bony tail

  • not like modern birds, don’t really have long tails

• small cartilaginous sternum but no keel

  • didn’t have skeletal architecture for bones to connect correctly

• Simple ribs (lacks uncinate process)

• had teeth

  • they were little, but there

Where did birds (like Archaeopteryx) come from?

• came from reptiles

• two hypothesis (must be able to explain)

  • thecodont hypothesis: a giant reptile thingy, really old ancestors

    • birds are NOT dinosaurs

    • similarites between theropods and birds is convergent evolution

  • Theropod hypothesis: more recent ancestry, putting birds in the dinosaur lineage

    • want to get to modern birds, must walk evolutionary lineage of dinosaurs

Thomas Huxley (late 1800s)

• Argued that birds evolved from theropod dinosaurs

  • Key differences though: no feathers, no clavicles, forelimb differed in Compsognathus

Gerhard Heilmann: Thecodont Hypothesis

• thought birds evolved separately

• because he didn’t enjoy the inconsistencies

• wrote the book: the origin of birds

• Mostly hung his hat on the act that more primitive reptiles had clavicles, and the known theropods did not

• Differences in hands and fingers

• Known dinosaurs did not have feathers, so maybe that took a lot of independent evolutionary time

• basically being like, look birds are so different from dinosaurs how can we say they come from dinosaurs

John Ostrom: Deinonychus antirrhopus

• found a transitional species Deinonychus antirrhopus

• had the things that Heilmann said we needed to find

  • Bipedal, terrestrial theropod dinosaur

  • Fused clavicles

  • Hollow bones

  • Semi-lunate carpal bone in wrist which allowed rotation (bird-like)

  • Uncinate processes (bird-like)

  • 16 shared traits in all!

• found the missing link we needed

Thecodont vs. theropod ancestry

• Birds evolved from theropods. The evidence is overwhelming.

  • we just hadn’t found the right species yet

Birds (Archaeopteryx) and theropods –shared characteristics

• Elongated arms and forelimbs

• 3-fingered clawed opposable grasping hands

• Large orbits (eye sockets)

• could see very well

• Flexible wrist (semi-lunar carpals)

• Hollow bones

• 4 toes per foot (3 main)

• modern birds is three in front, one in back, they twinning

• Bipedal digitigrade stance

• walked on its toes

• Fused clavicles

• FEATHERS

Feathered dinosaurs

• There is no exact line where we went from “feathered theropod” to bird

  • so many forms between dinosaurs and birds

• Deinonychus is certainly a feathered dinosaur

• Archaeopteryx is a “transitional state”

  • But commonly where the bird line is drawn

• Painted bunting is a bird

Timeline recap (don’t need to know dates, rather key features)

• 1860: first feather discovered

• found in Germany

• 1861: Archaeopteryx discovered (dated to 150 MYA)

• 1860s: Theropod hypothesis proposed (Huxley)

• thought they were from theropods

• 1920s: Thecodont hypothesis (Heilmann)

• no from more basal thecodont

• was able to disprove this with transitional state dinosaur found

• Argument: theropods lacked fused clavicles

• 1960s: Theropod hypothesis confirmed (Ostrom)

• Deinonychus similar to Archaeopteryx

• Including fused clavicles and semilunate carpals

• New feathered theropod dinosaurs discovered

Liaoning Province, China

• highly volcanic and great at preserving dinosaur tissues

• specimens die instantly and are buried (no scavenging)

  • so intact skeletons

• Chemical mix of ash and fine sediment helps preserve the skeleton

• one of the best place to find non skeletal structures, like feather

• the hotspot of where we found fossils, specifically bird

Sinosauropteryx (120-125 MYA)

• small theropod dinosaur

• among first feathered dinosaurs discovred (1996)

• small theropod covered in fine filamentous feathers

  • definitely couldn’t fly

  • proto-feathers did not have locking barbs, no flight

• structures called melanosomes were preserved (found in 2010)

  • first feathered dinosaur for whom we know its color

Fuzzy, with colors

Epidexipteryx (150 MYA)

• Theropod discovered in 2008

• Contemporaneous with Archaeopteryx

• Feathers with a rachis and vane, but vane was a single sheet (not barbs); body feathers also simple

• not a feature we’ve found in other birds

• not for flight, possibly for display

Ribbon tail

Protarchaeopteryx (125 MYA)

• Theropod discovered in 1997

• Was more than just fuzzy/filamentous feathers

• It had vaned feathers, with barbs on either side of rachis on forelimbs and tail

• Still primitive, symmetric feathers

• Lived more recently than Archaeoperyx (150 MYA) but bird traits were more primitive

• derived and primitive versions of birds lived all at different times, all over the place

Vaned feathers, primitive

More recent than Archae

Caudipteryx (125 MYA)

• Theropod discovered in 1998

• Also had vaned feathers, but like Protarchaeopteryx, not asymmetric and forelimbs were small (did not fly)

• Also lived more recently than Archaeopteryx (150 MYA) but bird traits more primitive

• had so many feathers and couldn’t fly, we don’t know why they had feathers

Vaned feathers, primitive

More recent than Archae

Sinovenator (130 MYA)

• Theropod discovered in 2002

• Same story: feathers, but no flight

• More recent than Archaeopteryx) but more primitive

Vaned feathers, primitive

More recent than Archae

Microraptor (120 MYA)

• Theropod discovered in 2003

• hindlegs are as feathered as forearm

  • modern birds don’t have flight feathers on their feet

• way different: asymmetric feathers (needed for lift) on both forelimbs and hindlimbs

• Strong claws on limbs, designed for grasping and climbing

• Is a flyer/glider, but with different body plan than Archaeopteryx

Doing its own thing

Sinornis (120-110 MYA)

• Bird! (Avialae) discovered in 1992

• Modern wrist bones for tucking wings

• Chest and shoulder structures solidly indicate flight

has the structures to fly!

Hesperornis (80 MYA)

• Bird! (Avialae)

• Clearly we are in legitimate bird territory now.

• Flightless and aquatic with teeth and beak

Vegavis

basically a goose that lived with dinosaurs

• bird (Avialae)

• solidly an Anseriform (water-fowl)

• probably honked

Importance of these transitional birds

1. The relationship between theropods and birds became incontrovertible in the 1990s.

2. Feathers evolved for things other than flight.

3. Multiple body plans evolved.

4. Primitive and derived bird traits existed simultaneously and all over the timeline.

• they’re all over the time line

Origins of flight

1) Arboreal theory (trees down)

• ancestors to flighted birds lived in trees and jumping/gliding in trees was the driving force that pushed for flight in these specimens

• wings and feathers improve gliding, leading to powered flight

2) Cursorial theory (ground up)

• Ancestors were ground-dwelling runners

• Feathers = insect net, leap to catch prey?

Arboreal theory (trees down)

• Strengths: most plausible with modern examples of gliders

• Weaknesses: ancestors mostly cursorial, terrestria

Cursorial theory (ground up)

• Strengths: cursorial ancestors

• Weaknesses: speed/lift problem

Wing-assisted incline running (WAIR)

• birds flap a lot to be able to get up steep surfaces

• would be good for getting up trees

• when young birds are growing their flight feathers, the flap before they can fly to climb to the edge of the nest

  • they do fluttery things to be able to learn to fly faster

• So it makes the Cursorial theory plausible

Earth’s worst day (66 MYA)

• asteroid travered the atmoshphere in a second, heated the air to 50,000F

• explosion was equivalent to 900 billion atomic bombs going off all at once

• fireball of plasma rick vapor, that expanded outwards into space

• superheated air immolated all life out to a few thousand kilometeres as massive bruning ejects rainied down across the globe sparking global wildfires

  • most of the globe was heated as pera pizza oven

• 100m megatsumami

Mass extinction

• a big cloud of dust surroinfed the upper atmosphere, blanketing the eath in complete darkness (and cold) for several months

• followed but thousands of years of greenhouse effect

• also globally widespread nitric acid rain

• No tetrapods >25 kg survived

  • ~75% of all species went extinct

Surviving the KT extinction

4 distinct (proto-) lineages of birds made it

• Paleognathae - the ratites

• galliformes - the upland game bird

• Anseriformes - waterfowl

• Neoaves - scattered members of the rest

Aepyornis (Elephant birds) - after meteor

Ratites – flightless birds – from Madagascar.

Weighed up to 1,000 lbs! Extinct 1000 yrs ago – probably by humans

Most closely related to the tiny New Zealand kiwi

Lays giant eggs

Diatryma - after meteor

7 ft tall, in North America

probably a strong and rapid runner

Large powerful beak, but not claws, so maybe herbivore?

Phorusrhacid (Terror Birds) - after meteor

Terror birds!! – 10 ft tall!

Flightless, carnivorous apex predators of South American (& Florida)

From the Cenozoic (just after K-Pg) until 2 MYA

Moa - after meteor

New Zealand flightless bird 9 species!

12 feet tall and over 600 lbs!

Systematics/Taxonomy/Phylogeny

• Systematics: the study of diversity and relationships among organisms and their evolutionary history

• Taxonomy: naming and classifying organisms

  • A product of systematics

• Phylogeny: depiction of evolutionary tree / hypothesis of relatedness

Classification schemes – Linnaean v.s Classification schemes – evolutionary v.s Classification schemes – cladistics

Classification schemes – Linnaean

• pre-Darwin no assumption of common ancestry

• Grouped by “essential” characters (e.g., beak shape, food structure)

  • religion used to explain

• Hierarchical ranks and binomial nomenclature still generally used today

Classification schemes – evolutionary

• the modern synthesis

  • use branching genealogy but allows overrides for practical groups

  • like here we just put birds

Classification schemes – cladistics

• Cladistics: 1950s in Germany;1970s elsewhere

  • Classification based on evolutionary history

  • Grouped by shared derived characteristics

  • Require monophyletic groups

    • can’t just carve out birds as not related to reptiles

    • fully resolved phylogenetic trees, where we are today

Monophyletic/Paraphyletic/Polyphyleitc

must include all common ancestors and descendent, no cut outs

contains a common ancestor and only some of its descendents, the carve out

being wrong, just grouping things together, not share a recent common ancestor

Phylogeny structural vocabulary

• Node – ancestor split point

• Clade – complete group of descendants

• Sister group – pair of closest relatives

• Laysan and Hawaiian duck

• Outgroup – distant baseline comparison

• ex: African black duck

Strong relationship has higher Posterior Probabilities

Resolving uncertainties – polytomies

Pre-genomics: evolutionary relationships within ratites were unresolved

• didn’t understand sister taxa

Post genomics: now resoled

Bird evolution, writ large

• Morphologically conservative group

  • unlike mammals birds are relatively similar

• Recent diversification and radiation (post K-T)

• Convergent evolution is rampant (flightlessness, nectivory, etc.)

  • ex: flightlessness has evolved multiple times

Historical avian classifications

Classification based on morphology has always been problematic. Example: Ciconiiformes – wastebasket for “long- legged wading birds”

• put all the long legged birds together

Early molecular work: DNA-DNA hybridization (Sibley-Ahlquist)

• First large-scale molecular approach to bird classification (1980s-1990s)

1) Melt DNA strands of closely related species (double-helix = single strand)

• can cook DNA until it splits into its two strands

• as we have single DNA that cools it will refuse with another strand to reform DNA

2) Stir and let anneal

• hybrid strands then bond

• Homoduplex Heron/Heron are more similar and shouldn’t melt as easily as Heteroduplex (A+B) which is more crudley put together

3) Test and compare new melting temperatures

Sibley-Ahlquist (1990) book made some new groupings that were suspect.

• helped move us in the right direction, get some genetic matches but then we also just threw in vultures

• this also rearrabged our phylogenetic understanding of bird orders and caused some crazy confusion

• this melting technique was also very inefficient

Modern genetic era

• Between 2000s and 2020s, we quickly moved to DNA sequencing

• Includes both nuclear DNA (comprehensive blueprint) and mitochondrial DNA (useful as molecular clock)

• Began with particular loci and regions, ends with whole genomes

• we have a lot more techniques and technology now

• have resolved Ciconifformes, only has one family Ciconiiformes (Storks)

Class Aves: Subclass Archaeornithes

Archaeornithes

“Old birds,” Archaeopteryx and dinosaur-like things

Class Aves: Subclass Neornithes

Neornithes

“New birds,” literally everything else

Class Aves: Subclass Neornithes: Superorder Odontognathae

Odontognathae

“Toothed jaw,” all extinct; like Hesperornis

Class Aves: Subclass Neornithes: Superorder Paleognathae:

Paleognathae

“Ancient jaw,” the 5 orders of ratites, plus some extinct ones

Class Aves: Subclass Neornithes: Superorder Neognathae:

Neognathae

“New jaw,” literally everything else

Neoaves - the five major clades

• Strisores

• Columbaves

• Gruiformes

• Aequorlitornithes

• Inopinaves

Neoaves: Strisores

Nightjars, swifts, hummingbirds, oilbirds, pootoos, frogmouths, owlet-nightjars

• things that come out at night and things with small feet

Neoaves: Columbaves

Pigeons, doves, mesites, sandgrouse

Neoaves: Gruiformes

Cranes, rails, sunbittern, kago, seriemas

Neoaves: Aequorlitornithes

Flamingoes, grebes, shorebirds/gulls, loons, penguins, tubenoses, storks, cormorants/boobies, pelicans, herons, ibis

• birds that get their feet wet minus ducks

Neoaves: Inopinaves

Hoatzin is the freaky outgroup of this clade

• Telluraves: “core landbirds” – all the rest

• Afroaves: hawks/eagles, owls, trogons, hornbills, woodpeckers, kingfishers/roller

• Australaves: falcons, parrots, passerines

Class Aves: full systematics (MUST KNOW)

• Subclass Archaeornithes: Archaeopteryx, etc. (extinct)

• Subclass Neornithes:

• Superorder Odontognathae: Hesperornis, etc. (extinct)

• Superorder Paleognathae: Ratites

• Superorder Neognathae:

  • Galloanserae: chickens and ducks

  • Neoaves:

    • Strisores: nightjars and allies, swifts, hummingbirds

    • Columbaves: pigeons and allies

    • Gruiformes: cranes, rails, and kin

    • Aequorlitornithes: flamingos, grebes, gulls, waterbirds, wading birds

    • Inopinaves:

      • Hoatzin

      • Telluraves:

        • Afroaves: hawks, owls, trogons, hornbills, woodpeckers, kingfishers

        • Australaves: falcons, parrots, passerines

Split 1:

Paleognathae vs. Neognathae

Paleognathae is seperate clade from everyone else

Split 2:

Galloanserae vs. Neoaves

Galloanserae is separate clade from Paleognathae and all Neoaves

4 Forces of flight

• lift

• gravity

• thrust

• drag

Generating lift in birds

1) Bernoulli’s law

2) Newtons 3rd law of motion

Bernoulli’s law

• we are in a fluid, surrounded by the static pressure of air

• evenly distributed on us

• static + dynamic pressure matter

• Static pressure + dynamic pressure = constant

• when moving in a medium static pressure decreases as speed increases and vice versa

• static pressure below will be greater than pressure above = LIFT

Airfoil

• air is faster on top so dynamic pressure is greater on top so the net force is lift

• Faster air (greater dynamic pressure) leads to reduced static pressure above

• Lift from static pressure underneath (Bernoulli’s Law)

Angle of attack

• angle of air hitting wing

  • ex: hand out of car window, turn hand sideways hand goes back, hand sideways and it goes back and up

Newtons 3rd law

• bird wings basically push against the air to create lift

• as wing strokes down it deflects air downwards, pushing bird up

  • like pushing down in a pool

Flight is a drag

• flow of air over an airfoil can create turbulence and as the body turns down the turbulence becomes stronger

  • friction between the air and wing surface = drag

• Profile drag: frictional resistance of wing/body passing through the air

  • profile drag = friction on wing

  • depends largely of angle of attack

• Induced drag: caused by vortices at the wing tips

  • air wants to move from high pressure to low pressure, can’t go through the wing so makes vortices at wing tips

Dealing with drag

• Problem: profile drag – caused by frictional resistance of body passing through the air

• Solutions:

  • Reduce surface area (like tucking wings)

  • Alula: helps to maintain laminar flow at low speed. The bird thumb

Dealing with drag problem 2

• Problem 2: induced drag – caused by wingtip vortices

• Solutions:

  • Reduce area of wing tip – narrow, pointed wings

  • Reduce area of wing tip – slots between feathers. These spaces allow for the vortices to fall through

  • Or fly very low to disrupt vortices, vortices smack down before hitting wing

Formation of flight

• Each goose has vortices coming off wing

• Angles just right you can catch the upstream of the vortices of the goose right in front of you.

How to make thrust

• Just tilt the airfoil

• increasing angle of attack, pushing down/both ways and generating thrust

• Outer parts of the wings (primaries) produce most thrust

Bird tails and flying

• Create lift when flared

• Can also be used as an air brake to slow down

• Swallows use it to change direction quickly

Wing dimensions

• Wing span – tip to tip

• Wing area – total wing surface

• Wing chord - width

Wing loading = bird mass / wing area

• ex: swallow, small wing loading v.s Swan big wing loading

Aspect ratio = wingspan2 / wing area

• ex: low aspect ration, broad, wide, shortwings ex: chickens, birds that don’t fly as much

• ex: high aspect ration, swallows, swifts, albatrose, long narrow wing for soaring flight

Potential exam question

put bird