Ornithology Final

Hyperphagia

Rapid feeding pre-migration

Giving up density

Threshold of food abundance at which bird chooses to abandon patch and move to new location

Levy flight

search pattern with mixture of short random and long random flights

Generalist

Birds that eat diverse foods: ex pigeons

Specialist

Birds that eat a narrow range of foods: i.e. osprey which only eat live fish

Search and recognition

Follows a continuum from active to sit-and-wait. Example: Flush-pursuit (stirring prey and then waiting)

Capture and ingestion

Example: trap lining, rotating through food sources. Often includes tool use

Preparation and ingestion

Example: caching, storing food sources (hummingbirds, sapsuckers). Tongue diversity, some birds use their feet

Pulverization and digestion

Example: cranial kinesis: able to independently move upper jaw or tips of bill, diversity of specialized tongues

Gleaning

Bird takes stationary prey while standing or hopping. Example: red-eyed vireo

Hovering

Bird picks prey from substrate via upward-directed flights; Example:Least flycatcher

Hanging

Bird flies to leaf or twig, hangs by feet to pluck prey. example: Carolina chickadee

Flush-chase

Bird flushes prey by fanning tail and flicking wings and chases in flight. Example: American redstart

Hawking

Flying prey are pursued by bird on the wing: Summer tanager

Benefits and costs of social foraging

Advantages: more eyes, greater predator vigilance, greater per capita food intake, learning from group.

Disadvantages: diminished resources, predator attraction, increased competition for mates.

Dolby and Grubb 1988

Mixed flocks in eastern deciduous forest

Ornament

Conspicuous physical trait exaggerated for display in mate attraction, product of sexual selection

Copulation-solicitation display

Stereotyped posture adopted by female to signal readiness to copulate

Male bowerbird mate selection

Males use elaborate construction to influence female mates. Male sings and displays when female visits, but female also considers quality of the bower

Blue tit mating preferences

Males are less likely to choose female blue tits with experimentally dulled crown color (UV reflectance)

Sexy son hypothesis

Breeding females achieve higher fitness by mating with attractive males because sons will inherit those attractive traits. Mates supply genes for development of healthy, viable offspring

Social monogamy

One female forms lasting pair bond with one male (social mate), but she can copulate with other males

Extra-pair copulation

Matings with other birds outside of a monogamous pair bond. occurs in 90% of species

Extra-pair fertilization

Fertilization resulting from EPC

Reproductive retaliation

One member of pair provides less parental care if offspring are not their own

Mate guarding

Male attends closely to female during her fertile period to reduce EPC

Genetic (true) monogamy

Social and reproductive pair bonds between one male and one female

Long term monogamy

Multiple breeding seasons

Short term monogamy

One breeding season

Polygyny

Males having sexual access to two or more females

Resource defense polygyny

One male with multiple females via defense of high-quality territory (ex red winged blackbird)

Female defense polygyny

One male with multiple females via defense against other males (ex. oropendola)

Lek

Aggregation of competing males that display to visiting females: example: sage grouse

Polyandry

Mating system with one female mating with multiple males, females accept sperm from more than one male per breeding season. Not very common in birds: Occurs in phalaropes where females mate with male, lay eggs and move on and male is responsible for parental care

Territoriality

Individual defends an area against other individuals. Costs: time and energy of display and chasing intruders, risk of injury, exposure to predators. Benefits: access to females and food for mate/young

Floaters

Individuals, often subordinate, of a territorial species that do not hold territories

Two primary functions of bird vocalization

Mate attraction and territory defense

Spectrogram

Graphic representation of frequency of a sound. Time is displayed on x axis.

Oscillogram

Shows volume/loudness of sound

Simple song species example

White-throated sparrow

Complex song species example

Common yellowthroat

Example of noisy sound

Hairy woodpecker

Non-vocal bird sounds

Drumming by woodpeckers, woodcock wing fluttering, common snipe tail, grouse drumming of wings against sides

Repertoire

The range of songs/calls a bird can make

Duetting

Coordinated simultaneous song of mated pair (e.g. Carolina Wren)

Song

Loud and complex vocalizations used to attract mates, or compete with others of same sex

Calls

shorter and simpler vocalization, facilitate interactions

Function linking to song structure

Titmouse “zee” alarm call is high frequency and narrow bandwidth making it hard for predators to locate

Birds that learn songs

Parrots, hummingbirds, songbirds

Vocal development

Learning is based on listening to a model sound such as a parent or neighbor, memorizing, and practicing. Birds experimentally isolated learn abnormal song

Sensitive period

The early period in a bird’s life where it is easiest to learn song (15-50 days old for songbirds)

Open-ended learners

Some species are able to learn songs throughout life

Subsong

Quite practice songs by young birds as they learn to sing

Local dialect

Birds learning neighbor’s songs and adjusting their song when they move to a new area, and may share new songs with neighbors

Species with high repertoire turnover

Indigo bunting: changed completely after 10 years in an area

Species with little repertoire turnover

Wood thrush: little change over 10 years

Effect of anthropogenic noise on song

Some species in urban areas and near roads change song, increase frequency and sing more often to reduce mask of urban noise

Suboscines

Flycatchers: only songbirds for which song is innate and they do not learn it

Costs and benefits of nest building

Costs: parental effort, risk of predation, sabotage. Benefits: Safety, thermoregulation, efficiency

Nest functions

Hold eggs in place for incubation, protect eggs from predators or elements, roosting, mate attraction, pair bonding activity

Brood parasite

Female bird lays eggs in the nest of another individual: brown-headed cowbird

Nest site selection and predation

Experiments show that playing back noises from brown-headed cowbirds results in host species nesting in denser vegetation

Nest site selection and competition

Predators develop search image after finding multiple nests with similar attributes, there are interspecific and intraspecific competition incentives to nest in less occupied locations

Nestless birds

Saves time and energy, exposed eggs may be less conspicuous. Examples: brood parasites, emperor penguins, white terns

Scrape nests

Shallow depressions with little or no nest material, formed by scratching ground. Examples are plovers, skimmers, and nightjars.

Platform nests

Shallow depression on a mound of nest material, can be on the ground, floating in water, or in trees or shrubs. Examples: doves, storks, eagles

Burrow nests

Underground, usually longer than they are deep, usually has an entrance tunnel. Examples: burrowing owl, atlantic puffin

Mound nest

Generally on the ground, large piles of nest material in cone or bell-shaped structure. Eggs may be on top or buried within. Examples: australian brush-turkey, flamingoes

Cavity nests

Nest located in empty space of large substrate, tree holes are most common. Examples: woodpeckers(create their own cavity) and owls (cavity adopters)

Statant cup

simple cup, built on hard surface, supported from below. Example: robins

Pensile cup

nest body usually unsupported, hanging by their rims, often attached to thin branches or reedy vegetation. Example: vireo

Adherent cup

Made from mud or saliva, attached to vertical surface. Example: barn swallow

Domed nest

Nest with overhead dome that aids in concealment: example ovenbird

Materials used to line nests

Material softer than outer structure used to insulate nest and prevent chicks from getting tangled in coarse outer material

Sex roles and nest building behaviors

In lekking birds and sexually dimorphic birds, females build nests. In polyandrous birds, males build nests. In monomorphic birds sexes take equal share in nest building

nest building frequency

Most birds build new nest every year, taking about 6-15 days

Ecological factors limiting clutch size

Birds trying to maximize offspring over their whole lifespan. Might lower clutch size one year based on resource availability or climate to save energy for the next breeding season

Nest destruction

Most birds will replace clutch if the whole clutch is destroyed, but many single-brooding species will not re-lay if hatched offspring are lost. Some birds will also replace single eggs if they are removed from the nest

Indeterminate layer

Lay replacement eggs until a clutch reaches a particular size

Determinate layers

Produce a fixed amount of eggs and will not lay replacements

Altricial young

Relatively undeveloped at hatching , naked or with sparse down, require complete parental care. Ex: songbirds

Precocial

Well developed at hatching, already feathered, capable of thermoregulation and locomotion, considerable degree of independence: ex ducks

Migration

regular, seasonal movement of individuals away from and back to breeding grounds (two-way trips)

Dispersal

Movement of an individual from one breeding site to another

Philopatry

Tendency to return to the same location over successive years. Non breeding warblers return to exact same territory, white-crowned sparrows return to original location the following year

Residence

Remain in same area year-round: Carolina wren

Facultative migration

Timing and distance of migration changes year to year in response to environmental conditions: yellow-rumped warbler

Obligate migration

Individuals migrate to the same areas on the same schedule, every year: Blackpool warbler

Nomadism

Less predictable movements, differ from year to year, breeding depends on food. Cedar waxwing

Partial migration

Combination of resident populations and migratory populations. Eastern bluebird

Leap-frog migration

Individuals that breed further north migrate to locations further south than other populations. Ex: fox sparrow

Loop migration

Spring and autumn routes differ resulting in a loop pattern of migration. Examples: Hudsonian Godwit

Migratory stopover site

Place for birds to feed and rest before continuing migration

Altitudinal migration

Seasonal movement up and down mountains: example resplendent quetzal

Irruptive migration

Occasional movement of large numbers beyond normal range for food.

Zugunruhe

Birds that are restless when ready to migrate

Orientation

Ability to determine directionality and bearings

Navigation

Ability to determine absolute geographic location

How do birds find direction to go?

Magnetic perception, solar cues, circadian clock, celestial navigation

Bird mortality

High mortality in migration compared to breeding and non-breeding seasons