Ornithology Lecture Exam 2

What are some of the ways birds deal with winter?

1. Torpor

2. “Tough it out”

3. Migration

Name some birds that can enter a torpid state of lowered body temperature and metabolism during winter

Some hummingbirds, swifts, and nightjars

E.g. Common Poorwill, Rufous Hummingbird

What is an example of a species having to “tough it out” during winter season?

The Boreal Chickadee

• Live year-round in northern boreal forests

• Territorial when breeding

• Form winter flocks

How is migration different from dispersal?

Migration is the large-scale return movement of a population, which occurs each year between regular breeding and wintering (non-breeding) areas.

Bird dispersal, specifically seed dispersal by birds (ornithochory), is a vital ecological process where birds play a crucial role in moving plant seeds away from the parent plant, aiding in plant reproduction and colonization of new areas.

What are two kinds of migration?

Diurnal Migration (day)

Nocturnal Migration (night)

Provide an example of species that migrate during the day time.

Hawks, Cranes, and Storks migrate during midday hours when thermals occur

Swifts and Swallows migrate when food resources are active

Why would birds want to migrate during the day?

1. Navigation and Vision: Birds that rely on visual landmarks and the Earth’s magnetic field for navigation is easier during daylight

2. Thermals and Soaring: Daytime thermals allow birds to soar while conserving energy

Provide an example of species that migrate during the night time.

The majority of species migrate almost exclusively at night

E.g. Nightjars, warblers, thrushes, sparrows, etc..

Why would birds want to migrate at night?

1. Feed during the day

2. Reduced Turbulence

3. Cooler (No Overheating)

4. Predator Avoidance

Provide a species example of long-distance migration

The Blackpoll Warbler flies 2,480 miles nonstop over the Atlantic Ocean for four or more days.

The Ruby-throated Hummingbird crosses the Gulf of Mexico ina single flight of 500+ miles

Provide a species example of Short-distance Migration:

Eastern Phoebe, Snow Geese

What causes Altitudinal Migration? Provide a species example

Birds practice altitudinal migration in response to seasonal variation in rainfall and resources

e.g. Quetzals, Mountain Quail, Townsend’s Solitaire, Snowcap Hummingbird

Describe the modes of migration

1. Complete Migration: The entire population leaves the breeding range

2. Partial Migration: Part of the species migrates and part over-winters on the breeding grounds, This type of migration is especially interesting because of the genetic components of migration.

What evolutionary gene does Migration fall under?

genus Catharus

Provide a species example of migration evolution

• House Finches: All eastern house finches
  evolved from an introduction of house
  finches to Long Island New York in 1940.
  House finches are now partial migrants
  and some individuals migrate to the gulf
  coast

• Blackcaps: migrate to the British Isles
  instead of Africa. May have to do with
  the abundance of feeders in Ireland and
  England

How did current migratory pathways evolve?

1. The most widely held theory
   suggests that northern migrant
   species evolved from tropical
   resident species in response to
   competition and climate
   change.

2. As breeding sites moved
   north/south from the tropics,
   birds developed migration in
   order to return to hospitable
   habitats during the colder part
   of the year.

Where is fat stored for migration?

Fat is stored all over but especially in the interclavicular region and the abdominal region— sometimes also in the thighs

**Long-distance migrants may carry 30-50% of total body mass as fat

How long do fat reserves last?

It varies by species:

• Shorebirds= 6,000 mi

• Many Passerines= 620 mi

• Ruby-Throated Hummingbird: 500 mi

What bird was first used to study orientation and navigation in birds?

The first banding occured in 1803 with an Eastern Phoebe wearing silk thread

Define homing and provide a species example

Homing is the ability of an experienced bird to return to a specific place

E.g., Manx Shearwater was transported from Wales to Boston and was able to find its way back in 12.5 days, covering about 3200 mi.

What is the Sun-Arc Hypothesis?

The "sun-arc hypothesis" in birds suggests that birds use the sun's position and movement across the sky to navigate, and they compensate for this movement using an internal clock or circadian rhythm.

What is the star compass hypothesis?

The "star compass hypothesis" suggests that migratory birds use the apparent rotation of stars around the North Star to orient themselves, learning to locate north before their first migration.

What is Geo-Magnetism?

Birds can detect which way is N or S depending on how the dip angle (inclination of the magnetic field) changes with latitude in a way that provides information about geographic position.

Where are the geo-magnetism receptors for pole-equator orientation?

For pole-equator orientation, magnetoreceptors, which are specialized cells that detect magnetic fields, are thought to be located in the eyes.

Name a species sample that uses olfactory cues for nest locating

Storm Petrels, Antarctic Prion

Describe a typical resident cycle for birds

A typical annual cycle for resident birds includes breeding, post-breeding molt, and overwintering, with some species also exhibiting fledgling dispersal and competition for breeding territories. 

How do seasonal cues affect tropical species?

Cues to breed (wet) and molt (dry) are closely tied to rainfall

What happens during the annual cycle of a migrant (temperate) bird?

• Spring migration

• Reproduction

• Molt

• Fall Migration

• Nonbreeding

• Molt

Many temperate-zone birds, especially those that migrate, molt twice a year, once after breeding and again in late winter or early spring.

What happens during the annual cycle of a resident (tropical) bird?

• Reproduction

• Molt

• Nonbreeding

How does latitudinal variation affect subspecies patterns?

Northern birds nest later than Southern birds, leading to staggered development of breeding condition (White crowned sparrow)

Prolonged breeding seasons in the tropics while strongly seasonal at northern sites (Brown Pelican)

Define Zeitgeber in correlation to the circadian rhythm of birds.

Zeitgeber “time givers”: An environmental agent or event that provides the cue for setting or resetting a biological clock

Keeping a bird isolated from Zeitgeber, the biological clock becomes free-running and the sensitive period may occur progressively earlier or latter than a 24-hr schedule.

How do birds control the timing of reproduction, migration, and molt?

1. Environmental light — day length

2. Changes in daily cycle — circadian rhythm (bio clock 1)

3. Internal annual cycle — circannual (bio clock 2)

How are short winter days beneficial to temperate birds?

They reset the refractory period. The testes will not grow in response to spring unless a bird has experienced a period of short day lengths

Describe the photoperiod of a bird’s annual cycle.

It is the time breeding to peak food abundance

Describe the photorefractory period of a birds annual cycle.

It ensures that breeding is triggered only after winter

What is the cost of migration? Provide a species example

Nine 6 day molt stages resulting in 15% extra metabolic costs

gambellii= 54 days

pugetensis= 47 days

nuttalli= 83 days

What species is an exception to the annual cycle of molting? — why?

White tern: Almost continuous molt throughout the year; stops at breeding since it requires up to 50% more energy.

How do molt, migration, and breeding success correlate?

Later molts that overlap with fall migration end up being paler in color, which reduces breeding success the following year.

Provide different examples of annual cycles in bird species.

• Sooty Terns= breed every 9.6 months

• King Penguins= 15 months to raise young, then molt. Breed twice every 3 years.

• Crowned Eagles (and other large birds) nest and molt once every 2 years.

Name an example of spacing behavior

Swallows practice individual spacing; differ innately in their degree of sociality.

Define territory

An actively defended, exclusive use space

Define territoriality

aggressive spacing behavior

Define home range

the total space used by an animal including undefended and shared use areas

Describe “Type A” territoriality; provide a species example.

“All purpose territory” including mating, nesting, feeding

E.g., Song Sparrows, American Robin, California Towhees

Describe “Type B” territoriality; provide a species example.

For the purpose of mating and nesting. Large area for breeding. Most feeding done elsewhere

E.g., Northern Harrier, Red-winged Blackbird

Describe “Type C” territoriality; provide a species example.

Only for the purpose of nesting. All feeding is done elsewhere. Many colonial birds such as gulls and terns

E.g., Common Murre

Describe “Type D” territoriality; provide a species example.

For mating. The “lek” territory= small area for pairing and copopulation. NOT used for nesting or feeding, lek species such as some grouse and some hummingbirds and some birds of paradise.

E.g., Greater Sage-Grouse

Describe “Type E” territoriality; provide a species example.

Winter territory for feeding only; defended, but differs from other types “by the absence of the sexual situation.” No ‘advertisement’ occurs. Either the same territory as the breeding territory or a new one

E.g., migratory Hermit Thrushes, resident Northern Mockingbirds

Describe “Type F” territoriality; provide a species example.

Roosting territories

e.g., Red-winged Blackbird, American Crows, European Starling

Who defends territories? Provide species examples

Most bird species defend at least some type of territory. Defense can be intra-specific or inter-specific.

Males in Red-winged Blackbird species are in charge of defending territory.

Describe the dynamic for group territory-dominance hierarchy. Provide species example

More than one pair occupies all the space, but each pair has a portion of the total space on which it is dominant to all other pairs

E.g., Steller’s Jay

Birds should defend territories when… (provide species example)

1. Resources are relatively predictable in space and time

2. Resources are not overly scarce

3. Resources are not overly abundant

E.g.,Golden-winged Sunbirds will defend temporary feeding territories of nectar-producing flowers until the costs outweigh the benefits

Benefits of territory defense include:

1. Exclusive access to food, cover and other resources

2. Greater opportunities for mating

Explain the relationship between territory size and body mass

Territories of birds increase directly in relation to body size, energy requirements, and selection of food types.

For a given body mass predators require larger territory than herbivores.

Define “agnostic behavior”

The competitive encounters between rivals that results in a complex mixture of aggression (attack, threaten) and escape (submit, flee) actions- called agnostic behavior

What is the difference between flocking and aggregation?

Flocking is any group of two or more birds whose formation depends on positive responses by individuals to members of their own or other species.

Aggregation is a group of individuals that is drawn together by some extrinsic factor such as a localized food or water source

What are some of the costs for flocking?

• Association with more dominant individuals

• Competition for resources

• Exposure to disease

What are some of the benefits for flocking?

• more food

  • assistance locating food

  • assistance catching food

• safety

  • increased vigilance

  • predator confusion

Why do some birds practice colonial nesting? provide a species example

13% of species practice colonial nesting for synchronized nesting and safety in numbers BUT it can also lead to greater risk of disease and competition

E.g., terns

Define monogamy and provide a species example

• Prolonged and essentially exclusive pair bond with a single member of the opposite sex for the purpose of raising young

• 91% of birds are socially monogamous

• E.g., Northern Cardinal, Western Bluebird, Cedar Waxing

Why are most animals polygynous?

Sperm is cheap, eggs are costly

What are some varieties in monogamous parental involvement?

1. Most songbirds - males feed brooding females and/or help to
   feed the young.

2. Herons, egrets, some woodpeckers and many songbirds -
   males also share in incubation.

3. Geese, swans, gulls, terns and many shorebirds - males
   commonly place themselves in danger by vigorously defending
   the nest and young from predators.

What species practice life-long pair bonding?

Geese, Swans, Cranes, Petrels, etc..

What assets of a male can courtship displays show?

1. Health (e.g., House finch plumage)

2. Ability to provide food

3. Ability provide shelter

4. Ability to defend territory

Why are mutual courtship displays important in monogamous pair bonds?

1. Reaffirms pair bond (in life-long mates)

2. Stimulate courtship

3. Coordinate breeding behavior

E.g, Albatrosses, Grebes

How common are extra-pairs in socially monogamous pairs?

75% of all socially monogamous bird species produce extra-pair young

Low frequency: Snow Goose (2.4%)

High Frequency (Superb Fairywren > 75%)

What are some benefits for extra-pair copulation (EPC) for females?

• fertility insurance

• genetically diverse young

• improved genetic quality of young

• access to resources

What are some benefits for extra-pair copulation (EPC) for males?

• increased fitness

• possible future mate acquisition

• insurance against mate’s infertility

Define polygyny and provide a species example

• 1 male pairs with two or more females

• 2% of all birds are polygynous

e.g., Marsh wren

Define polyandry and provide a species example

• 1 Female pairs with two or more males

• Fewer than 1% of all birds

E.g., Northern Jacana, Red Neck Phalarope, Spotted Sandpiper

Define polygynandry and provide a species example

• Multiple males pair with multiple females

• fewer than 1% of all birds

E.g., Acorn Woodpeckers

Define promiscuity and provide a species example

• Indiscriminate sexual relationships, usually brief in duration. No social pair bonds

• 6% of birds are promiscuous

E.g., Cock-of-the-rock

What is the “hotspots hypothesis” for lek promiscuity

males gather at sites where females are more likely to congregate

What is the “hotshots hypothesis” for lek promiscuity

males cluster because subordinate males gather around highly attractive males to have a chance to interact with females drawn to hotshots.

What makes lek promiscuity possible?

Resources are abundant enough that females can raise offspring alone. Males cannot defend resources because they are not clumped spatially, and males may be too conspicuous to offer parental assistance.

Explain cooperative breeding using a species example

Cooperative Breeding is where “helpers” provide parental care for young that are not their own.

• care includes food, territorial defense, nest construction, incubation, and defense from predators.

E.g., Florida Scrub Jay, Acorn Woodpecker

Describe some disadvantages of staying home for helpers

• Few vacant territories of good quality habitat

• Few suitable breeding partners available

• Little change of successful reproduction until they gain parenting experience

Describe some benefits of staying home for helpers

• survival improved via group membership

• chance to improve survival of close relatives

• chance to quire superior territory either by monitoring vacancies in neighboring sites or by inheriting natal territory.

What are nests?

1. structures to hold and protect eggs

2. structures that protect developing young

3. a safe place to roost even when not breeding

4. a way to attract mates

5. a courtship location

6. an object built during pair formation and solidification

What species make cavity nests?

woodpeckers, owls, parrots, many passerines

e.g. Northern Flicker

What species make burrow nests?

swallows, kingfishers, petrels, other seabirds

E.g. Horned Puffin

What species make scrape nests?

shorebirds, gulls, terns, nighthawks

E.g. Least Tern

What species make platform nests?

grebes, raptors, doves

E.g. Western Grebe

What species examples make statant cup nests? (hard support below)

Anna’s Hummingbird + American Robin

What species examples make pensile cup nests?

golden-crowned kinglet + Hutton’s vireo

What species examples make pendulous cup nests? (entrance at top)

Bullock’s Oriole

What species examples make adherent cup nests? (mud or saliva)

Barn Swallow

What species examples make domed nests?

Western Meadowlark

What species examples make globular nests?

Cactus Wren

What species examples make mound nests?

African Social Weavers + Brush Turkey

What are some of the inputs of breeding?

• Effort

• Energy

• Time

• Care

What are some of the costs of breeding?

• risk of death

• reduced health

• reduced future breeding potential

(all consequences of iteroparity)

What are some of the benefits in breeding?

• fitness (having your genes carry on to the next generation)

Provide an example for one of the fastest breeding systems

Red-billed Queleas take up entire areas..

2-3 million breeders in 100 hectares

How have seabirds like shearwaters chosen breeding strategies to limit predation risk?

• gulls account for 2% in annual adult mortality almost entirely on breeding colonies (not bad)

• On colonies, adult survival is strongly positively correlated with the number of breeding gulls also on the island.

What are some of the selective pressures that influence the risk of nest predation?

• Nest Architecture

• Nest Placement

• Clutch Size

• Nest Defense

• Nest Parasitism

Provide a species example of nest-predation rates in North American birds

• American Robin: 39-54%

• Yellow-billed Cuckoo: 39%

*Rates will vary year to year and by region

Provide a species example of nesting behavior evolution

Tooth-billed Pigeon found only on Samoa

• Ground nester originally

• Adaptively shifted to tree-nesting after cats were introduced by whalers

What materials are nests often constructed with?

• Leaves

• Twigs

• Stones

• Sticks

• Fibers

• Mud

• Ribbons

• Feathers

• Spider Silk

• Snake Skin

• Hair

• Insects

What can be done for nest defense against predators?

• Build on an island

• Build near a wasp colony

• Use fake nests

• Mob predators