Exam 2: Ornithology

Why do birds migrate?

• access food in different places more efficiently

• thermoregulate in warmer places

• safer

• easier to find mates

Why do birds not migrate?

• stay in the same place and going into torpor

• continue to find food

• don’t need to waste energy

• no risk of other predators

Torpor

Bird enters a voluntary, hibernation-like state to survive extreme cold or food scarcity by significantly lowering its body temperature, metabolism, heart rate, and breathing rate.

How do birds prepare for migration?

• through annual cycles of fixing their feathers, molting, hyperphagia

Hyperphagia:

a critical pre-migration behavior involving a short-term, dramatic increase in food intake to store fat for long distance flights

Molting

a process where birds shed old and damaged feathers, to start growing new ones for flight, mate attraction, and insulation

Nutritional Content:

High sugars for high body fat

• 3-5% summer

• 30-47% premigration

Apteria:

the parts of the birds that are unfeathered

Where do birds store fat?

They have a bald spot around the fercula and another one in the abdomen

What are the 4 main North America Flyways?

• Atlantic

• Mississippi

• Central

• Pacific

Neotropical Migrants:

bird species that breed in the United States and Canada during the northern summer and migrate to the "Neotropics"—Central America, South America, and the Caribbean—to spend the winter

How many birds travel through the North American Flyways?

5 billion birds, around 200 species

Stopovers:

where birds stop to rest between migration and regain their energy and may find food

• Delaware bay

• Suriname

Delaware Bay:

Rest stop for birds like “Redknot” where they feed off of horseshoe crab eggs

Horseshoe Crab Blood:

Blue blood contains immune cells that clot instantly upon contact with bacteria, ensuring vaccines are safe before they are administered

Limulus Amebocyte Lysate (LAL):

a substance that tests vaccines and medical devices for bacterial contamination, specifically endotoxins

Arctic Tern:

species of bird that travels around 12,000km and they experience more sunlight than any other species

How do we track migration?

• banding

• GPS

• radar

• stable isotopes

• audio recordings

• reporting observations

Banding:

fit them with unique, numbered metal bands on their legs, and release them to track their movements, lifespan, and population trends.

• shooting it

• misnetting

• Monitoring Avian Productivity and Survivorship (MAPS)

Monitoring Avian Productivity and Survivorship (MAPS):

A specific, long-term monitoring program that uses banding data (not GIS mapping) to study the vital rates of landbirds during breeding.

GPS:

tracking birds with “mini backpacks” that deliver signals to satellites to determine precise locations

Radar:

helps track huge migratory flocks in maps (looks like a big cloud)

Stable Isotopes:

Specific # of neutrons that tell what an animal has eaten, scientist use this to map chemical signatures of the feed

Audio recordings:

scientists put mics on skyscrapers to record the songs of all the birds that travel through

How do birds navigate?

• visual landmarks

• sun // star compass

• geomagnetism

• odors

• twilight angles

• learning

Geomagnetism:

magnetite, magnetic fields located in bird’s upper beak that align with the Earth’s magnetic fields

Star compass:

guide themselves based on how bright the starlight is, helps them determine North Vs South

Sun compass:

sunlight guides them with their mental compass to help them determine what time and direction they need to go

Learning:

Juvenile birds learn from adult birds on when and how they need to leave for migration

How does migration affect conservation?

• breeding grounds

• wintering grounds

• stopovers

Dioecious:

Having distinction between males and females

Dimorphism:

Difference in body shape, size, and color between male and females excluding their reproductive organs

Anisogamy:

Sexual reproduction via 2 different gametes of males and females

Sexual selection:

Individuals with certain traits are more successful at finding mates than others

Dichromatism:

A type of color vision where an animal possesses only two types of functional cone cells (photoreceptors) in its eyes, limiting its ability to perceive color compared to humans

• sexual

• general

What might birds use to select mates?

• plumage

• vocalization

• good genes

• runaway selection

Runaway selection:

females prefer brighter colors and more complicated songs, so it forces males to learn and evolve to be sucessful at mating

Good genes:

producing genes that show phenotypic characteristics to attract mates

• peacock

Displaying:

Ritualized behaviors and physical characteristics/signals that help males assert their territory, get mates, and predator defense

Lekking:

Males go to a SPECIFIC spot and display (dance, boom, sing)

• similar to displaying, but its in ONE specific spot

Its a hot spot, hot shot, and female preference

Bowerbirds:

display by building and decorating elaborate, specialized structures called bowers to attract, impress, and woo female partners for mating.

How does territoriality affect mating?

• most dominant males get the mates

• some males don’t have enough territory so they try to sneak into other territories for a better chance at finding a mate

Lek polygyny:

a male typically defends a territory or resources to attract multiple mates. A male who mates with many females in a specific communal area

Courting:

“dating” or where birds figure out if its the correct mate

• mate fidelity

• mating for life

Monogamy:

1 male with 1 female

Polygamy:

1 male with multiples females

Extra-pair copulations:

“cheating”

• male may mate with other females besides their partner

• female may leave her nest and go mate with other males

Why do males keep taking care of chicks even if theyre not theirs?

Its difficult for males to determine if a chick belongs to them or not, they’re so monogamous that they decide to keep raising them

What are the differences in chromosomes?

males are heterogametic in mammals

• males XY

• females XX

females are heterogametic in birds

• males ZZ

• females ZW

What are the sex hormones?

• LHRG (GnRH)

• FSH and LH

• Testosterone

• Estrogen (both male and female produce this)

What are some effects of testosterone and estrogen?

• appearance // seasonal (colors of skin or feathers can change based on how much testosterone the bird has)

• behavior (some birds might be more dominant than others)

Reproductive Organs:

• Photoperiod drives change in testes production

  • works great because its less weight for them to carry

• left ovary is only functional in reptiles/birds

  • gametes are only produced in left side

Copulation:

cloacal kiss: usually male gets on top of the female and try to touch their cloaca with the females cloaca

• sperm travels from vent to female cloaca through their reproductive area

Cloacal Protuberance:

Some species of birds have it, serves at the “penis”

• some females prefer this in males because it allows sperm to travel further through

Sperm Competition:

Males compete to see who has the most successful sperm

• which one will travel further through the females uterus

• which one holds the most sperm

  • can vary from 200 million to 8 billion

Sperm Storage:

Sometimes females hold sperm in the oviduct until they’re ready for ovulation

Ovulation:

the release of a mature yolk (ovum/oocyte) from the ovarian follicle, captured by the oviduct for potential fertilization and egg formation

Fertilization:

Occurs in the infundibulum

• produces calcium to make shell for eggs

Egg Development Steps:

1. Ovary (with mature ovum)

2. Infundibulum (ferilization)

3. Magnum (first layers of albumen added)

4. Isthmus (inner and outer shell membrane, albumen added)

5. Uterus with shell gland (pigment added and shell)

6. Uterovaginal junction (where females store sperm)

7. Vagina

8. Cloaca

Protein Spindle in egg:

Serves as stabilization for the egg because outside temperature can kill the egg

Photoperiod:

the duration of daily light exposure used as a reliable seasonal cue to time critical life events like breeding, migration, and molting

Effects of pesticides in eggs:

cause lower fertility, reduced hatchability, eggshell thinning, and increased embryo mortality

• DDT

• DDE

DDT

prevent the female body from producing calcium for eggshells

Clutch:

total set of eggs laid by a female bird during a single nesting attempt

Synchronous hatching:

when eggs hatch at the same time

• no siblicide

• all your hatchlings grow at the same time

Asynchronous hatching

when eggs hatch within one day apart

• if predator eats one of the eggs or temperature kills one of the eggs, you still have other eggs

Laying Sequence:

• depends on time of development

• timing of incubation

• clutch size

• synchronous vs asyncrhonous

Timing of incubation:

some species can delay incubation until temperature is ideal for hatching

Time of development:

how long the egg (or chick) takes to grow

Embryo Development:

The egg shell is able to exchange air and it can ventilate carbon dioxide

• Yolk sac is similar to the “placenta” in mammals

What factors lead to breeding?

• photoperiod

• air temperature

• rainfall

• food

• social interaction

Social Interactions:

juvenile birds have never done breeding behaviors and they take this time to learn from mature birds when they’re with other species

What is the purpose of nesting?

• protection from predators

• camouflage

• thermoregulation

What is the name of this nest? What type of bird does this?

What is the name of this nest? What type of bird does this?

What is the name of this nest? What type of bird does this?

What is the name of this nest? What type of bird does this?

What is the name of this nest? What type of bird does this?

What is the name of this nest? What type of bird does this?

What is the name of this nest? What type of bird does this?

What is the name of this nest? What type of bird does this?

What is the name of this nest? What type of bird does this?

What is the name of this nest? What type of bird does this?

What is the name of this nest? What type of bird does this?

What is the name of this nest? What type of bird does this?

What is the name of this nest? What type of bird does this?

Moundbuilders or Megapodes:

small-to-medium ground-dwelling birds that do not use body heat to incubate eggs

What is the name of this nest? What type of bird does this?

What is the name of this nest? What type of bird does this?

What is the name of this nest? What type of bird does this?

Nest construction:

different species of birds have different ways of building their nests but most of them use their down feathers because they serve as the best insulators to help with the thermoregulation of their eggs

What are these mechanisms used for by birds?

What is the name of this nest? What type of bird does this?

Nest Sanitation:

procedures that birds do to keep their nests clean so that the odor doesn’t attract predators or any other potential predators

What are the 2 ways for nest sanitation:

• fecal sacs

• fecal projection

Fecal Sacs:

mocous-covered membrane packages containing the waste of nestling birds, acting like disposable diapers to maintain nest sanitation

• adult birds eat the fecal sacs of their chicks to prevent the odor from spreading

Fecal projection:

behavior (nestlings and raptos) where they forcefully expel their excrement away from their immediate location to protect their nests

Incubation effort:

certain species have the support from both the males and the females, others are only females, and others are only males

• 37% female only

• 6% male only

• 57% both

shifts can last from 1-2 hours to a month or more

Brood Patch:

a featherless, highly vascularized area of skin on a bird's abdomen that develops during the breeding season to transfer body heat directly to eggs.

Turning eggs:

parent birds turn their eggs during incubation to help stimulate growth and development