Migration and Navigation Lecture

• Why migrate?- food/hormones (survival, reproduction)

• Alternatives?- caching, slowing metabolism, continuing to forage

• Why not Migrate?- saves energy

• How do birds prepare for migration?

  • annual cycles

  • feathers molted- makes sure they’re in good shape

  • eat foods with high fat/sugar

• Changes in body mass (bulking season ong)

  • Hyperphagia

  • Nutritional content

  • 3-5% summer, 30-47% premigration

  • organ and muscle use (decrease in mass)

• North American Flyaways

  • 5 billion birds, 200 species

  • Neotropical migrants

  • (Atlantic, Mississippi, Central, Pacific paths)

• Stopovers

  • used to feed and refill (gas stations for birds)

    • ex: Delaware Bay- shorebirds eating horseshoe crab eggs

• Artic Tern

  • 12,000 km (9000 mi)

  • breed in the Artic and go to Antarctica in the winter

• Bar-tailed Godwits

  • Alaska to Australia

• How do we track migration?

  • banding

  • GPS

  • Radar

  • Stable Isotopes

  • Audio Recording

  • Reporting Observations

• How do birds navigate?

  • Relocation experiments

    • ex: white-crowned sparrows

  • ways:

    • Visual landmarks

    • sun compass

    • star compass

    • geomagnetism

    • odors

    • twilight angles

    • learning

• How does migration affect conservation?

  • breeding grounds

  • wintering grounds

  • stopovers

Lecture- Mating

• Dioecious- 2 sexes

• dimorphism- Different look, color, and sizes

• Dichromatism- 2 different plumage colors (males- bright females-dull)

• Anisogamy- 2 different sizes of gametes and different levels of production of gametes

  • millions of sperm vs 1 egg take the same amount of energy

  • more energy needed to make egg

• Sexual selection-

  • what might birds use to select mates?

    • plumage and vocalization

• Good genes and runaway selection

  • Runaway selection: trait becomes maladaptive (more risks of predators or death)

    • ex: winter wren, peacocks, antlers on deer

• Displaying and lekking:

  • lekking- go to certain location and display

    • usually a bunch of birds displaying in one location

• Why lekking?

  • hot spot- lots of birds there (rick’s fr)

  • hot shot- dominant male will get you the hoes

  • female preference- females want safety from predators and resources (picking up a baddie at a grocery store)

    • ex: blue manakin

• Bowerbirds

  • male birds making a structure to show off

• Territoriality

  • How does territoriality affect mating?

    • female wants male with good resources and territory

    • Gradient of polygamy- male mates with multiple females

      • some males have no breeding success

• Courting and coupling

  • why go through courtship?

    • don’t want a random bird (need the best of the best)

    • birds go through courting period

  • Mate fidelity

  • Mating for life

    • raptors and geese

• Monogamy vs Polygamy

  • Polygamy- multiple mates

    • most species show polygamy

  • Extra-pair Copulations: multiple males per clutch

Lecture- Copulation

• Male-ZZ Females-ZW

• Sex Hormones- know full word

  • LHRH (GnRH)

  • FSH

  • LH

  • Testosterone

• Effects of Testosterone and Estrogen

  • Appearance

  • Behavior

• Reproductive Organs

  • seasonal growth

  • Asymmetry (left ovary- active and produces egg) (right ovary- inactive)

• Copulation

  • Cloacal kiss (DISGUSTINGGG)

    • hit and quit (lil quickie)

  • Male birds- cloacal protuberance

    • swelling

  • Ruddy duck- phallic organ (bruh it looks like a corkscrew but the hoes love it)

• Sperm competition- different ways for males to compete with sperm

  • sperm ejection

    • 200 million to 8 billion sperm in one ejaculation

  • ex: Dunnock- pecking at cloaca to remove sperm

  • ex: copulatory plug- drying agent that closes cloaca to prevent sperm ejection

• Ovulation and fertilization

  • ovulation- release of ovum

    • occurs near INFUNDIBULUM

  • sperm storage

  • ruptured follicle become corpus luteum

    • corpus luteum- helps prepare for pregnancy

• Egg Development

  • albumen- egg whites

  • egg yolk- nutrition/food

• Completed eggs

  • chalaza- provides stabilization for middle portion

  • know the other parts

• Effects of pesticides

  • DDT and DDE

    • killing the birds because birds were eating poisoned insects

    • caused brittle egg shells

    • no calcium deposits or vitamin D

• Laying Sequence

  • Depends on time of development

  • Timing of incubation

  • Clutch Size

  • Synchronous vs Asynchronous hatching

    • Synchronous- develop at the same time

    • Asynchronous- develop as soon as they are laid and get incubated (don’t develop at the same time)

• Embryo Development

  • Yolk (nutrition)- attached to abdomen

  • KNOW PARTS (chorion, albumen, amnion, allantoic sac, etc)

  • chick can communicate in the egg (via air cell)

• What factors lead to breeding?

  • MAIN ONE: Photoperiodism

  • air temperature

  • rainfall

  • food

  • social interactions

Lecture- Nesting

• what are the purposes of nests?

  • insulation, protects from predators, prevents eggs from rolling

• variety of nests

  • bowl/cup nests- straw and soft grasses and sticks

  • EYRIE NEST- raptor nest used year after year with large sticks

  • hanging nest- vireo hanging nests on trees (mud, saliva, webs, etc)

  • Weever nests- weevers placing grass with tight knit walls

  • Floating nests- grebes use mats of floating vegetation

  • platform nests- coots build their own islands to make a platform

  • swift nests- cliff swallows use mud packed to make a nest

  • saliva nests- swiftlets use saliva to make a cup in a cave

  • natural cavity nests- using cavities

    • gila woodpeckers and small owl species use cacti

  • Turkey nests- ground exposed nest (no adult incubating? vulnerable nest)

    • hyperphagia often occurs before nesting (adults don’t have time to eat)

  • duck nests- ground nests near water surrounded by thick vegetation

    • smell can attract predators

  • BRUSH TURKEY or MOUND BUILDERS- use compost on top of eggs by piling on top of eggs to incubate them (leave nest- no parental care)

  • Burrowing owl nests- using burrows

  • Cavity within muddy banks- bank swallows

  • Murre- cliff nesters lay eggs directly on cliff (pointed eggs prevent rolling)

• Nest construction:

  • grass plant material

  • cotton fluff

  • mud

  • feathers (eider down)

  • moss

  • sticks

  • hair from mammals or dead animals

  • human trash

• Clutch- group of eggs

• Brood- hatched eggs

• Double Crested Cormorants- use dead trees for location of stick nests

• Social weavers- social species build nests together (community)

• Nest Sanitation- prevents smells and parasites

  • fecal sacs- chicks produce protein structure and adults remove it or eat it (tasty)

  • fecal projection- project poo poo (air strikes bomb them, keep bombing them)

• Incubation effort

  • 37% female only, 6% male only

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

• Brood patch

  • patch that makes contact with the egg

  • lost feathers and use direct contact

  • can be used to identify whether a female has chicks or not during mist netting

• Turning eggs

  • turning/rolling the egg over and moving eggs around to thoroughly provide warmth (rotisserie chicken style)

• Incubation and development

  • temperature (36-41 degrees C)

  • Water retention

  • Candling- holding a light on egg to see development of egg

• Hatching

  • Air cell- chick breaks into air cell and then cracks through egg shell

  • Egg tooth- hard piece of keratin used to crack cell

  • Birds can eat shell for calcium

• What causes a nest to fail?

  • #1 cause: predation

  • Starvation- not enough food

  • Desertion- adults feel risk and may leave to survive

  • Hatching failure- bad development

  • Adverse weather- i.e. snow storms

• What factors influence nest success?

  • nest success- chick fledges or chicks hatch

  • need right temperature and good incubation period

  • good nest with good location and materials

  • experience- more success with experienced parents

  • luck

  • enough food

  • right time of the year

Lecture- Growth and Development

• Altricial vs Precocial

  • precocial- more independent and ready to go

    • eyes open, feathers, stand up earlier, walk/swim after hatching

    • strong legs

  • altricial- more care, time, and protection till independence

  • Egg size and Yolk size

    • altricial- SMALLER egg and LESS yolk

• Ground nesters- more precocial (on ground, better be ready to go)

• Passerines- more altricial (need to be better at flying)

• KNOW CHART

• Brain size- precocial have bigger brains at time of hatching

• Small intestine- Altricial have larger small intestines

  • a lot of growing to do, so need more surface area to absorb food

• Growth rate-

  • Altricial need to grow faster

  • Precocial- slower

  • fledglings often bigger than parents

• Thermoregulation

  • feathers- natal down feathers

  • brooding- warmth obtained from baby birds huddling together

• Why is independence important for nest success?

  • baby birds are vulnerable and need to grow up

  • adults want to take care of themselves again

  • quicker fledging means less vulnerability sooner

• Nutrition

  • feather and bone growth- need to gain more protein

    • ie hummingbirds eating spiders

  • fat deposit

  • muscle growth

  • crop milk

• Why would chicks be larger than adults

  • larger chick- more chance of survival

• Begging

  • more noise- more food

  • noisiest chick- gets fed more (competition)

  • risk?- predators may be attracted to nest

  • benefits?- more food

• Yellow bright mouths- serve as a target to help adult see mouths

• Sibling competition-

  • Asynchronous laying- more competition

  • Yolk provision- last egg has more yolk than previous egg

  • Testosterone provision- increase growth rate/aggression/begging for the later eggs

    • yolk and testosterone provision- catches later eggs up to earlier hatched eggs

  • Siblicide- siblings abuse the last chick

• Leaving the nest

  • nestling- bird in a nest

  • fledgling- bird that has left the nest

  • Altricial vs. precocial- determines time of fledging

  • Mortality (i.e. cavity ducks falling from tree cavity)

• Development of skills and knowledge

  • nature vs. nurture?- both

  • innate behavior reinforced by experience

  • food soliciting- innate

  • predator avoidance- birds have to learn this

• Imprinting

  • critical learning period- have to learn behavior (do this on adults)

    • chicks will imprint on people (in lab settings, chicks will sometimes think they are humans)

    • gotta learn who they are and what species they are

  • movement and sound

    • look for this and queue on

  • recognizing individuals

    • adults can recognize their chicks

    • chicks can recognize their adults

  • What chatgpt says: imprinting- involves the young animal recognizing and bonding with the first moving object it encounters, usually its parent or a surrogate caregiver. This process is crucial for the young animal's survival and development, as it helps them learn important behaviors, such as social interactions, communication, and foraging skills, from their caregiver.

• Development of Assortative Mating

  • chicks look for mates that look like their parents

    • i.e. snow geese (white parents- chick wants white mate, vice versa for gray)

• What are brood parasites?- rely on other species to take care of their young

  • cowbird- obligate brood parasite

  • innate chatter call

  • chicks grow up with a different species

  • don’t become attracted to the nest species tho

  • aggressive and will outcompete other siblings

• Learning Life Skills

  • foraging

  • migrating

  • vocalizing

  • parent-offspring conflict

    • i.e. peregrine falcon

Lecture- Parental Care and Reproductive Success

• Roles of a parent

  • brooding- protect a chick in nest

  • feeding

  • protecting

  • teaching

• What are the costs of raising young?

  • fitness

  • stress

  • predation risk

• how does a bird manage their costs?

  • mating effort- may put less effort if it isn’t his sperm (YOU ARE NOT THE FATHER)

  • Nesting Favoritism- adults feel like they can’t raise all so they favor the yapping ones

    • sex ratio- stressed bird puts more testosterone into the egg and changes the sex of eggs to male

    • Brood reduction- ignoring/kicking a chick out to have more success

    • desertion- really stressed, low fitness bird may abandon chicks

• Life History

  • what is life history?- the series of events from birth through reproduction and eventually death that characterizes the life of an organism

  • what are different life history strategies?

    • R-selected- high fecundity and low parental investment

      • early reproductive maturity

      • high reproductive rate

      • short life expectancy

    • K-selected- low fecundity and high parental investment

      • delayed reproductive maturity

      • low reproductive rate

      • long life expectancy

  • what are the costs and benefits of each?

    • R-selected-

      • benefits: high reproductive rate, fast population growth, low parental investment

      • costs: high mortality rate, short life span, vulnerable to environmental variation (natural disasters)

    • K-selected-

      • benefits: high survivorship, long lifespan,

      • costs: low reproductive rate, delayed maturity, high parental investment

    • Fecundity- production of offspring (reproduction of eggs)

• Life History

  • Juvenile mortality- higher in r-selected

  • age of first breeding- k-selected takes them longer

  • fecundity- # of chicks/eggs produced (high fecundity- large clutch size)

  • Adult mortality- k-selected is lower

• Fast-slow axis- relative terms (species may be k-selected to some species or r-selected to others)

• Life Tables-

  • Sx: survivorship for age class

  • Lx: Probability of survival of this age class from fledging

  • Bx: (Sx * Lx) number of female offspring per female subject

    • Age-Specific Fecundity

  • LBx: (Lx * Bx) Summation of LBx= the population replacement rate (Ro)

    • Greater than 1: sustaining

    • Less than 1: not sustaining

    • KNOW HOW TO DO THE MATH

      

• Lifespans

  • what are the advantages and disadvantages?

    • R: short lived- hope you don’t die first or have bad conditions before reproducing

    • K: bad year? not a big deal

      • ex: Albatross- 67 years old named Wisdom that got hella babies

• Survivorship

  • R-selected: low survivorship in youth (losing over 80% of offspring)

• Cooperative Breeders: yearlings help raise next clutch

• Fecundity- # of chicks produced

  • nestling mass is small- more likely to double brood

  • high food availability- more likely to double brood

  • things to consider: probability of double brooding, food availability, nestling mass

    

• Age of Maturity-

  • why delay?- more wisdom, can learn more

    • sexual maturity

    • foraging skills

    • behavioral skills

    • territoriality and mortality- can’t breed until higher up on the pyramid

• What affects annual reproductive effort?

  • food availability

  • predation

  • weather

  • previous effort- more effort from one clutch one year causes a smaller clutch next time so parents can recover

  • adult age

  • stress

  • adult sex

• What determines clutch size

  • size of clutch increases as latitude increases

    • gets away from equator

    • seasons are shorter, have less time before conditions change

    • predation: less predation away from equator

      • a lot of predators in the tropics

  • predation increases, clutch size decreases

    

• Why would reduced clutch size reduce predation?

  • less chicks, quicker time to get them out of there and out of harm

• Lacks’ Food Limitation Hypothesis

  • clutch size is impacted by food availability

    

• Survivorship Curves:

  • 

  • Type 1: (strongly convex)- high survival rate throughout lifespan; most mortality at end of life

  • Usually few offsprings and lots of parental care (humans, large mammals)

  2. Type 2: (straight)- survival rates do not vary much with age, constant decay in survivorship (small birds, reptiles, rodents, perennial plants)

  3. Type 3: (concave)- high mortality very early in life

  • Usually a lot of offspring, little or no parental care (oysters, fish, invertebrates)

Lecture- Food and Foraging

• what do birds eat?

  • seeds/fruit- easily dispersed (soft mast)

  • acorns- (hard mast)

  • insects (larval stages/caterpillars)

    • aerial insectivore- catching insects in air

    • foraging for insects on vegetation or on other mammals

  • carnivores- fish, small mammals, amphibians, other birds (will also eat insects)

  • scavengers- carrion

  • birds will also eat a variety of food groups during different seasons (i.e fruit during fall, acorns in winter, insects in summer, etc)

  • odd example: vampire finch (finch love eating some boobies and boob blood fr)

  • other food sources:

    • eggs

    • leaves

    • soil- eating for calcium

    • nectar

    • sap

    • plastic?- birds eating this- leads to death or malnutrition

• special adaptations: feet and bills

  • i.e. bald eagles using feet to hold food while using bill to pull the food

  • i.e. crossbill finch- has a cross bill that is used to eat pine seeds (eat clay to digest resin)

• Specialist vs Generalist

  • specialist-has a narrow dietary niche and typically consumes a specific type of food or a limited range of food items.

    • negatively impacted if food source is no longer available

  • generalist-has a broad dietary niche and can consume a wide variety of different food types or food items.

• how much do birds eat?

  • weight: 10 g 100g 1000g

    eats: 3.5 g 10g 40g

    % 35% 10% 4%

    • smaller birds: higher metabolism, need more food (SA:V)

• Food choices

  • how do birds decide what to eat? most reward for minimal risk

  • Abundance vs. Availability

    • Abundance- how much is there

    • Availability- can they actually get to that food (predators, risks, blockages, etc.)

  • Search Image

    • takes a second to register something as food (takes time to switch from food type A to food type B)

  • Balanced Diet- one food type does not satisfy all nutritional needs

• Feeding efficiency

  • two things to consider

    • nutritional content

    • handling time

• Optimal foraging

  • clumped, uniform, random

  • traplining- move from flower to flower and then circle back again

  • feeding in groups-

    • multiple species have different strategies (efficient and increases survival)

  • attraction to other birds

• why not forage optimally?

  • predation (not going to sit at a bird feeder all day and let the opps see you)

  • need other food sources

• Niche partitioning

  • same food sources and same size? (i.e. owls and hawks)- hunt at different times of day

  • Temporal partitioning- feeding at different times

• When do energy demands change?

  • hyperphagia- more food needed before nesting and migration

  • fat deposits- thick yellow mass of fat shows hyperphagia

• Caching- storing food for later

• Cycles in abundance of food

  • cycles can be seasonal or annual

  • impacts abundance of the “hunter”

• Annual cycles

  • migration- food availability is a migration driver

  • laying eggs/hatching- done when food is available

  • ultimate vs. proximate factors

    • what is the most powerful proximate factor? photoperiod

    • what is the most powerful ultimate factor? survival and reproduction