Class: Aves

Birds & Invasive Species

• Rodents are responsible for more than half of bird extinctions in the last century • Domestic cats: - Estimated to 1.3-4 BILLION birds annually in the U.S. alone - Suspected to be the single greatest source of human caused mortality

Clutch size in birds

• Species is one of the biggest determinants of clutch size (range = 1 -25 eggs) • Each species tends to have an average clutch size that varies little • Females lay one egg/day until it is reached -then begin incubating • Note: eggs don't start developing until incubation begins

Tinamous

•Can fly but mostly ground dwelling •Keel on sternum is present but reduced

Ratites

•E.g., Ostriches, rheas, kiwi, emus & (extinct) elephant bird •Flightless, terrestrial •Lacks keel on sternum •Long necks and legs •Good RUNNERS

Order: Galliformes

"Fowl or The Gallinaceous /Chicken-like/Upland Game Birds" Generally large-bodied and largely non-migratory, males in this group often exhibit showy displays. • Ground dwelling/nesting; precocial offspring • Some (e.g., quail) form secretive flocks called coveys (E.g., Grouse, Quail, Pheasants, Turkeys)

Order: Apodiformes

"Hummingbirds & Swifts" These birds are the most agile and impressive fliers. Some members can fly forward and backward and others remain airborne for months at a time. Special adaptations for flight: • Tiny feet • Small legs with limited function • Long wings (Swifts, Hummingbirds)

Order: Accipitriformes

"The Accipiters" Members have strong talons, sharp beaks, and are known for their excellent eyesight and hunting ability • Nest in trees, cliff ledges, cavities • Offspring altricial • Diurnal (Hawks, Eagles, Vultures)

Family: Corvidae

"The Crows, Ravens, Magpies & Jays" • The most intelligent of all birds • Many form flocks • Flock of Crows is a "MURDER" • Most non-migratory • Diet- Diverse! Seeds, insects, small vertebrates, carrion

Order: Falconiformes

"The Falcons" Members have strong talons and beaks specialized for killing prey with a hook/tomial tooth; these birds are known for their speed and the fastest animal on earth is a member. (Falcons, Caracaras)

Order: Pelecaniformes

"The Long-legged Water/Wading Birds" Members generally have long legs, are fish eaters, and many nest in colonies or rookeries; offspring are typically altricial. (Pelicans, Herons, Egrets, Ibises, Spoonbills)

Order: Strigiformes

"The Nocturnal Birds of Prey" These birds are nocturnal predators, cough up pellets of undigestible material, are silent fliers, and can rotate their head nearly 270 degrees. • Use cavities or nests of other species • Altricial offspring (Owls)

Order: Passeriformes

"The Perching Birds" This is the largest and most diverse order of birds, some sing and others do not, the all have feet designed for perching and many are neotropical migrants. Are good learners with relatively large brains • Constitute >50% of all birds • Found on all 7 Continents - S. Georgia Pipit -only Antarctic passerine sp. (Perching Birds, Songbirds)

Order: Charadriiformes

"The Shorebirds" A highly diverse order known for their long annual migrations, and diverse array of bill morphology that facilitates specialization in finding and eating certain prey items in sand, mud, and water; young are typically precocial. (Shorebirds, Gulls, Terns)

Family: Laniidae

"The Shrikes" • True predators • Hooked bills • Bill similar to Falcons -severs spinal cord of prey • Diet - large insects (68%), reptiles, small mammals and ....birds! (28%) • Open areas- perch and wait

Family: Tyrannidae

"The Tyrant-Flycatchers" •Bristles at the base of bills •Songs are innate -not learned

Order: Anseriformes

"The Waterfowl" Members are tightly associated with water, many (but not all) exhibit sexually dimorphic plumages, and offspring are typically precocial. Pointed Wings • Socially monogamous • Male = Drake • Female =Hen (Ducks, Geese, Swans)

Family: Troglodytidae

"The Wrens" • Small • Bills thin & curved • Often 'cocked' tail • Diet -insects

Order: Columbiformes

"The pigeons and doves" These medium sized birds are usually buff-colored, plump, have small heads and produce a substance called "pigeon's milk" from the lining of their specialized crop that serves as a food for young. • Always lay 2 eggs • Altricial young (Pigeons, Doves, Dodo)

Order: Piciformes

"The woodpeckers and their allies" • Bill shapes vary greatly! These birds have chisel like bills, zygodactyl toe arrangement, long tongues, and a nictitating membrane as adaptations for their unique lifestyle. (Woodpecker, [Toucan, Honeyguides, Jacamar])

Polyandry

1 Female & Multiple Males • Very few (<1% ) species • E.g., spotted sandpiper -female lays for ~4 mates; Jacana • Females are larger or more colorful • Multiple males set up nests in her territory -she lays eggs in all • Male does all the incubation/caring for young

Monogamy

1 Male & 1 Female • 90% of avian species are socially monogamous • We now know that most partners cheat sexually • Regardless, partners stay together until young disperse...some partner for life

Polygyny

1 Male & Multiple Females • ~2% of birds; (5% in North America) • Most nest in marshes or grasslands. -E.g, Red-winged blackbird • Multiple females nest within male's territory -he breeds with all but doesn't provide parental care

What Factors Pose the Biggest Threat to Birds?

1. Habitat Loss 2. Climate Change 3. Invasive Species

Typical avian life history

1. Incubation: eggs 2. Nestling phase: post-hatch but before young can leave the nest 3. Fledgling phase: young can leave nest but still need help 4. Post-fledging: lazy teenagers hanging around 5. Dispersal: young leave to find their own breeding territory

Pair bonding

A mating system in which a male and female form an exclusive mating relationship • Vary from brief unions to life-long bonds

Covey

A small party or flock of birds.

Dabbling ducks:

Also called puddle ducks, surface-feeding ducks (E.g., Mallards, Wood duck) • Feed on surface or land (plants, seeds, insects) • Take off directly into the air - hind toe is "spur-like"

The Megapodes

An entire family of birds that builds mounds instead of nests. • Precocial offspring; have no parental care.

Neotropical Migrants

Birds that breed in North America and spend winter in Central & South America or the Caribbean • Migrate hundreds to thousands of miles each year! • Some shorebirds and raptors are also neotropical migrants

Avian Reproduction

Birds use internal fertilization - 97% of bird species lack copulatory organs ("cloacal kiss") • Increased calcification = harder shell • Nest building and parental care • Oviparous

Ground nesters

Bobwhite, many ducks, geese

Shrub nesters

Cardinal, Brown Thrasher, catbird

Family: Falconidae

Common Features • Head is bullet-shaped, neck short • Wings long, pointed • Eyesight extraordinary • ID prey up to 3000 ft away-movement to 5000 ft. • Do not build nests (E.g, American Kestrel, Peregrine Falcon)

Make-up of an avian egg

Depending on the species, yolk makes up 20-70% of an egg • More yolk = better developed hatchling

Birds & Climate Change

Directly affects 2/3 of North American species • Disrupts timing of resource availability during critical periods • Breeding • Migration

Contributions to Diversity & Distribution of Aves

Endothermy, Amniotic Egg, Powered Flight

Hallux

Enlarged flexible hind toe used for perching

Atricial vs Precocial - Implications

Food availability & predation pressure are important determinants of which strategy evolves • Birds don't have a choice - each species has evolved such that their young fall at a certain point along the Altricial-Precocial gradient

Avian mating systems

Four main types of avian mating systems 1. Monogamy: > 90% of avian species 2. Polygyny: ~2% of avian species 3. Polyandry: ~ 1% of avian species 4. Promiscuity: ~ 6% of avian species

Zygodactyl

Having two toes pointing forward and two backward.

Family: Accipitridae

Hawks, kites, eagles, harriers, old world vultures Common characteristics • Medium-large• Wingspan 2-6 ft. • Largely brown, gray or black above; paler underneath • Barred or streaked with brown

Family: Ardeidae

Herons, bitterns, egrets • Many with long pointed bills • 4 toes; not webbed

Family: Threskiornithidae

Ibises & Spoonbills • Feed by probing mud/filter feeding • 4 toes; not webbed

Determinate Layer

Lay fixed number of eggs no matter what, then stop and begin to incubate.

Brood parasitism

Laying eggs in the nest of another bird with hopes that your offspring will be raised by others. (E.g., Cuckoos, Brown headed cowbirds)

The Avian Egg

Necessities for survival: • Active gas exchange • Proper temperature (usually 100-112 °F) • Too cold = NO development • Too hot = Death • Submerge an egg in water for an extended period = drowning Pointed egg benefits Color benefits

Family: Cathartidae

New world vultures • Most hold wings in a dihedral (V-shape) • Head and neck naked (E.g., Black Vulture, Turkey Vulture)

Clutch Size

Number of eggs per nest, produced by 1 female Many factors can influence clutch size: • Species • Age • Health • Food Availability • Season • Location

Diving Ducks

Often grouped as "Bay ducks" or "Sea ducks". (E.g, Scaup) • Dive to forage on fish, mollusks • Legs are closer to tail -means they skitter across water at take off - hind toe has lobe

Passenger Pigeon

Once the most abundant bird in North America • Flocks of hundreds of millions • Covered the sky for 14 hours • Driven to extinction by humans • Declined precipitously 1870-1890 • Last observed in 1914

Canopy nesters

Oriole, Warbling Vireo, Bald Eagle

Family: Pandionidae

Osprey • Feeds on fish • Distinctive crook in wings with dark wrist patch • Plunges into water (head and feet first) • Reversible outer toe and sharp spicules on feet • Zygodactyl toe arrangement

Egg production

Ovulation & laying take ~ 24 hrs • Birds can store sperm • Ova mature hierarchically• Mature ova is released from ovary & fertilized • Coated with nutrients and shell along the way • Uterus (shell gland) adds the final layers • Females must have adequate calcium to produce a strong eggshell

Promiscuity

Pairing is extremely brief - for copulation only • About 6% of species• Males & females gather to form Leks during brief breeding period • Males display in courtship arenas that contain few or no resources -females choose • Males are usually noisy or colorful • Sage Grouse Lek • Less than 10% of males achieve 70-80% of mating!

Avian nests

Provide protection & Create a microclimate for eggs Nest location is usually crucial • Typically isolated & hidden • But, exposed & conspicuous for some species • organized in colonies/rookeries

Precocial offspring

Relatively well developed -need less care • E.g., grouse, quail, killdeer, waterfowl, Barnacle goose • Longer incubation • Larger eggs with greater yolk content (30-40% yolk) • Active chicks -can leave the nest at hatching • Well developed fuzzy down • Examples -grouse, quail, killdeer, waterfowl, Barnacle goose

Mid-height nesters

Robin, blue jay

Syrinx

Sound organ of birds

Family: Cardinalidae

The Cardinals and their allies" (E.g., Grosbeaks & Tanagers)

Family: Trochilidae

The Hummingbirds • Includes smallest bird sp. (2.25 inches tip-to-tip) • The only backwards flier • Brilliant colors -many iridescent • Sexually dimorphic • Nectar feeders • Long slender bill-narrow gape • Migrate long distances (E.g., Ruby-throated Hummingbird)

Sub-Order: Passeres

The Songbirds Most Passerines in N. America are songbirds •Muscles and anatomy of syrinx is more complex •Songs are learned-not innate •The Lyre Bird (Australia) is one of the most impressive learners

Oscines

The Songbirds • 17 Families of Songbirds in North America • Make up the majority of neotropical migrants

Sub-Order: Tyranni

The Suboscines Only 1 Family of Suboscines occurs in N. America

Family: Apodidae

The Swifts • Duller in color than hummingbirds • Not sexually dimorphic • Aerial feeders • Short bill-wide gape • Nest on vertical surfaces (e.g, chimney, bridge support) • Altricial offspring (E.g., Chimney Swift "The Flying Cigar")

Family: Pelecanidae

The pelicans • 4 toes, Webbed

Incubation period

The period from laying (or start of incubation) to hatching

Brood patch

Thickened, featherless patch on the abdomen used to cover and incubate the eggs

Altricial offspring

Underdeveloped -need lots of care • E.g., cavity nesters, most songbirds, hawks, herons, • Shorter incubation • Smaller eggs with lower yolk content (15-27% yolk) • Blind, naked, & virtually immobile at hatching • Essentially helpless & CANNOT thermoregulate

Birds & Habitat Loss

Via deforestation, logging, farming, buildings, constructs, wind farms

Indeterminate layers

Will replace eggs if some are removed OR will stop laying if eggs are added

Family: Picidae

Woodpeckers (family) Special Adaptations of Woodpeckers: • Stiffened tail • Chisel-like bills • Tip renews itself • Barbed tongue used to extract wood boring insects (E.g., Pileated Woodpecker, Red-Cockaded Woodpecker)

Stopover sites

locations where migrating birds take a short break to rest, eat and drink for maintenance, and/or await favorable migratory conditions. • Red Knot migrate 8,000 miles each way and use stopover site in Delaware Bay; depend on horseshoe crab eggs - Population decline of 70%

Tomial tooth

morphology of beak adapted for severing spinal cords

Suboscines

relatively poor singers

Cavity nesters

woodpeckers, wood ducks, tree swallows, Great-horned Owl, bluebirds

Avian Conservation Issues

• About 13% of all birds are threatened with extinction -IUCN, 2017 • Many more are considered 'at risk' due to global changes

Super-Order: Paleognathae

• Ancient group of bird families • Nicknamed "The Ratites & Tinamous"

Types of nests

• Cavity nesters • Ground nesters • Shrub nesters • Mid-height nesters • Canopy nesters

Family: Anatidae

• Ducks, geese, swans • Webbed feet with elevated hind toe • Males have copulatory organ (penis) • Plumage is only sexual dimorphic in duck • Usually only during breeding season

The Dodo of Maritius Island

• Flightless bird • 2.5 ft tall • 9 in. bill • Fruit eaters • Driven to extinction ~350 yrs ago • Few preserved artifacts - still little known about its ecology