Vert Class 16: Avian Biology

polygyny

- a male mates with more than one female

secondary wing feather position and function

-attached to ulna, provides lift

true adaptations for flight

-mobile shoulder -elongated forelimb -sternum enlarged with keel (where flight muscles attach) -ilium and ischium fused into synascrum - helps with shock absorption -asymmetric feather

paleognathae

-old jaw -consist of "ratites" -ratites are ~ 13 species of flightless birds show a Gondwanaland (southern continent) distribution

How the proximal part of the wing creates lift #1

1).Wing (airfoil) shape: Convex dorsally, concave ventrally This creates unequal air pressure against the two surfaces because air has to move farther and faster to get over the top convex surface. The result is lower air pressure above the wing than below it....this shape automatically produces lift!

Bird Diversity

>10,000 species -29 orders, 187 families, 2000+ genera -most species of any terrestrial vertebrates

Bird habitats

Arboreal terrestrial semi-aquatic burrowing

aspect ratio of wings

Aspect ratio: wing length / wing width High aspect ratio wings with pointed tips minimize inertial drag. Good for long distance flying; use of wind Low aspect ratio wings are more maneuverable. They often achieve lift by being highly cambered

female benefits to extra pair copulations in birds

Benefits to Female Female increases chances that all her eggs will be fertilized Female can increase fitness of her male offspring - "sexy sons" hypothesis Female can lay eggs in the other male's nest, leaving him to care for the offspring

male advantages to extra pair copulations in birds

Benefits to Male Male can sire more offspring by mating with multiple females Male maximizes chances that at least some offspring will survive The male benefits from having another male care for his offspring

advantages to extra pair copulations in birds

Benefits to Male AND Female 1. Increase the fitness of offspring by mating with an individual of better genetic quality. 2. Increase the diversity of its offspring by mating with more than one partner.

body contour feather

Body contour feathers. Barbs are confined to the distal part. They fill out the body contours and facilitate streamlining. They also protect underlying downy feathers and shed water.

bristle feathers

Bristles protect eyes and nostrils.

bird clavicle specialization

Clavicles are fused at their distal ends to form the furcula (wishbone) (17) that provides further bracing, as well as a "spring" action that helps push the wings

Bird hind limb and joint specialization

Distal elements of the hindlimb are greatly elongated (2, 3). Note position of the knee and "ankle". -Remaining metatarsals are fused with tarsals into a tarsometatarsus (2). -The hind foot is elongated (1), and the 5th toe absent.

Downy feathers

Down feathers are fluffy & flexible. They serve as thermal insulation

Bird egg laying features

Eggs are laid in nests and incubated by one or both parents (usually both)

Features of ancestral theropods retained in birds

Feathers Air sac system Lung ventilation mechanism Hollow bones Bipedalism Intratarsal joint Oviparity Amniote eggs Egg incubation Parental care

exaptations that facilitate flight

Feathers Skeletal pneumatization (hollow bones) Air sac system Lung ventilation mechanism

filoplume

Filoplumes function as sensory structures

how construction of wing feather facilitates flight

Flight feathers have a long tapered shaft (rachis) that bears closely-spaced side branches called barbs that form a vane. Each barb bears barbules that bear hooks that hold adjacent barbules together. -Flight feathers. Wing feathers (remiges) and tail feathers (rectrices) are large and stiff feathers modified for flight. They are classified as a type of contour feather.

How the proximal part of the wing creates lift #2

Increased angle of attack (wing tilt) Tilting the wing decreases pressure above the wing and increases pressure below it, resulting in upward lift. The steeper the angle, the more lift. -alula counteracts stalling by preventing airflow disruption at steep angles (>15) -directs airflow over the wing top, thus allowing maximizing wing tilt and increasing lift

What features can counteract inertial drag?

Long wings ensure that the tip vortex disturbances are widely separated and more wing area exists where air can flow smoothly. Tapered wings reduce the area at the wing tip where induced drag is the greatest.

two major clades of extant birds

Palaeognathae (old jaw) neognathae (new jaw)

wings maximized for thrust:

more primary wing feathers -longer wings to minimize drag -tapered wings

bird forelimb specialization

The forelimb is very elongated. It bears elements of just 3 digits, fused into a carpometacarpus (23-26).

bird pelvis specialization

The ilium and ischium are elongated and fused with abdominal vertebrae into a synsacrum (8). It functions in shock absorption.

bird vertebrae specialization

The neck is long and flexible with many vertebrae (12). The rest of the vertebral column is rigid.

The role hearing plays in avian biology

The sensitivity of the auditory system of birds is similar to that of humans. Owls are acoustically the most sensitive birds. Owls have a facial ruff that focuses sounds with frequencies above 5 kHz on the external auditory parts of the ears and amplifies them by 10 decibels. Slight asymmetry in the position of the ruffs allow the owl to pinpoint prey. Asymmetry of the aural system of owls also includes the skull itself. One ear opening can be markedly lower than the other. Species with this degree of asymmetry have the greatest auditory sensitivity.

bird sternum specializations

The sternum (15) is greatly enlarged. It bears a keel from which the flight muscles originate

bird tail specialization

The tail is short (10) with few vertebrae. The caudal vertebrae are fused into a pygostyle (9) that supports tail feathers

ancestral archaeopteryx features lost in birds

Toothed beak wing claws long tail with many feathers

The role vision plays in avian biology

Vision is highly important in flying birds, for locomotion, sensing of prey and predators, and in mating. Birds have relatively large eyes and a very well developed visual system. They have excellent color vision (far better than most mammals) that extends into the uV spectrum. Optic lobes of the brain are relatively large.

How vocalization is achieved in birds

Vocalizations are achieved by means of an organ called the "syrinx". It lies where the trachea divides into the two bronchi. Sound is produced by vibrations of some thin membranes in walls of the syrinx. Being located at the junction of two air streams lets some birds produce two different sounds at once, and even to sing duets with themselves

the role vocalizations play in avian biology

Vocalizations play essential roles in social behavior, establishment of territories, courtship, mating, maintenance of the pair bond. Species - specific calls serve as pre-mating isolating mechanisms. Within a species, males and females (and even offspring) have distinctive calls. Different calls serve particular functions.

polyandry

a female mates with more than one male

monogamy

a pair bond between a single male and a single female. The pairing may last for an entire season or even for a lifetime.

position and attachments of the major abductor and adductor that respectively raise and lower the wing

adduction: towards midline abduction: away from midline -sternal keel allows for attachment of flight muscles -flight muscles act as like a pulley system, supracoracoideus is interior to coracoid and sternum, "pulls wing up" pectoralis is exterior to sternum and coracoid, "pulls" wing down

neognathae

all other extant birds -one notable group is the Passeriformes (perching birds): which consists of 6,000 species -most are songbirds ex: cardinal

polygamy

an individual has more than one mate in a breeding season

primary wing feathers position and function

attached to carpometacarpus -provide thrust

achaeopteryx features found in birds

bipedal -wings beak tail still has feathers on it, yet shortened (asymmetrical) contour feathers

Wings for maximum lift:

convex dorsally, concave ventrally -allula -increased angle of attack -maximal secondary wing feathers slotted wing tips

forces on a flying bird

drag counteracted by thrust gravity counteracted by lift

How bird beaks are adapted for specific diets

ex: warbler (insect catcher) Short beaks with a wide gape are good for catching insect prey on the wing ex: eagle (flesh tearer) . Carnivorous birds often have heavy pointed beaks to kill their prey ex: merganser (fish eater) Fish-eating birds have beaks with a hooked tip that is used to seize fish.

How bird feet are adapted for habitats and lifestyles

fast running large body feet (ostrich - have 3 digits - good for traction) capturing prey (hawk, eagle have talons) Swimming (ducks have webbed feet specialized for swimming)

Specializations of birds not found in archaeopteryx

flying toothless beaks no tail sternum (helps in flying mechanism)

bird site of fertilization

internal fertilization

How can features of a bird minimize viscous drag?

streamlined body minimizes viscous drag

Bird geographical distribution

worldwide geographical distribution: arctic to equatorial