ornithology lec exam 3

behaviors that define a mating system: (6)

1. display

2. intersex communication for mates

3. sexual division in gametes / parental care

4. copulations (broken down by frequency, timing, and “who”)

   • in their first potential breeding seasons. juveniles help parents raise brothers and sisters instead of raising their own

give an example of an opportunistic tactic used in addition to mating systems

extra pair copulations

• found in every avian family

• even in monogamous species

• detected through paternity studites, plumage variation, vasectomized males of pair bones (if female is still laying eggs → EPC must have happened)

describe the two broad categories of mating systems:

• monogamy:

  • socially monogamous - help each other raise kids, but will take opportunistic tactics when they can

  • each male and female have a SOCIAL bond with one other individual

    • will hang out out together and be social

    • seen in 90% of birds, only 3% in fish (less parental investment from other groups of animals - males can’t provide incubation/milk)

• polygamy:

  • ~10% of birds

  • males or females pair with more than one individual

  • further subdivided into:

    • polygyny: one male, 2+ females

    • polyandry: one female, 2+ males

    • promiscuity: no bonds, just coming together to make babies

      • usually no male care provided at all

    • variable system: mating system varies based on levels of competition vs parental care

reasons for monogamy:

1. endothermy:

   • fragile eggs, require many days of incubations

   • males can also provide valuable parental care when hatched

     • during 1st week of life, chicks can’t thermoregulate

       • males can help incubate

     • vs mammals and fishes which can’t help much

2. lack of opportunity for polygyny:

   • even if biparental care is unnecessary, can happen during highly synchronous breeding, high levels of competition (everyone on the lookout for sneakers), resources not clumped

     • ex) longspurs (highly synchronous) mate over 1-2 days, not many opportunities to find another partner

how can polygyny evolve?

• if mates / resources are defendable (spatially or temporally clustered - one male can take control)

  • if this can happen: individuals need to be able to take advantage of potential opportunities for polygamy

why is polygyny more common than polyandry?

• females need to invest more heavily in eggs

• males can leave as soon as they finish copulating

  • sperm is cheap!

• tends to be a lack of certainty of paternity

  • males don’t know if they are the father or not

give an example of a mating system having different costs / benefits

1. Pied Flycatchers:

• male and female form a primary bond

• after the female has mated with the territorial male, that male will then set up a distant secondary territory to attempt to attract a second mate

  • the territory needs to be distant so that the primary female doesn’t find out

• secondary females are tricked into thinking that they are the primary mate, when in essence - they have a lower reproductive success because most male help is spent raising the young from the first female

• male doesn’t lose anything by setting up a secondary territory, but benefit is potentially very high (at virtually no cost to him)

• females (which lose their mates during incubation) will actively solicit copulations from neighboring males

  • trying to trick the male into helping them raise offspring that are not theirs

  • will do this when incubating eggs → males won’t take the “bait” if the eggs are already hatched

2. Salt Marsh Sparrows:

• no territorial defense, no parental care, no pair bonds

• males and females come together solely to exchange gametes

• 56/60 broods had at least 2 chicks from different parents

• 1/3 of broods had a different father for each chick in the nest

• most common pattern was: multiple fathers fathering 2 or more chicks

• males sire chicks up to 1.4 km from original capture site - suggests they are moving around a lot

• a lot of males sire chicks in multiple nests, separated by up to .5 km

give an example of variation within monogamous systems:

• length of pair bond (some species bond for life)

what are the two basic varieties within polygynous systems?

1. resource defense polygyny:

   • linked to food or nest sites

2. female defense polygyny:

   • males defend females rather than resources

   • precondition is a natural clumping of females for some reason

give an example of resource defense polygyny:

Red-winged Blackbird

• females tend to cluster together on better territories

• if male territories differ enough in quality, a female settling on an already occupied territory by another female can rear as many offspring as a primary female on a shitty territory

  • even if settling on a better territory, they have to forgo parental assistance from male (to primary female)

• polygyny threshold: determined by where first female settles (best spot until threshold is reached)

  • females have to choose between having a higher fitness, and environmental quality

  • no fitness advantage once threshold is reached: secondary female is gaining environmental quality instead of fitness (being on a better territory)

  • anything above the line: fitness wins ; below line: female needs to make choice between territory and fitness (sole female on shitty territory or secondary f.male on good territory)

give an example of female defense polygyny:

Oropendolas:

• females like to nest together in trees → males will defend the tree with all of the nests - establishing a polygynous system

**a system is likely to be polygynous if the male is bigger than the female**

what are the two types of polyandry?

1. cooperative polyandry (only 4 sp.)

   • 2+ males mate with females and assist in rearing young

   • saturated environments

   • very stable groups

   • skewed sex ratio (more males than females - females not a limiting factor)

   ex) Galapagos Hawks:

   • very few females (skewed sex ratio)

   • females hold maternally inherited territory (stable groups)

   • galapagos islands → not a lot of habitats (sat. environment)

2. sequential polyandry: (also rare)

   • females mate with and lay clutches of eggs for a sequence of males

   • males have the nests (evolution gone wrong)

   • females are larger in this system - territorially aggressive sex

ex) Jacanas:

• females will kill a male’s offspring in an effort to lay eggs in his nest (also seen in lions)

what is promiscuity?

• males and females only come together to mate

resource defense:

• males defend resource that females need to visit

  • ex) Orange-rumped Honeyguides: males defend honey

display site defense:

• thinks like leks

• at least 30 sp. do this

• set up if resources for females aren’t monopolizable

• precocial young render little parental care - males don’t need to be there / help much

  • ex) Mannikins: males do elaborate dances, includes alphas and betas

  • ex) Sage Grouses: males come together and females will walk through territory

    • best males near the center, younger males (wrose dancers) stay near edge

    • females wander through lek, trying to find the best dance moves

    • some males in leks get way more copulations than others, some don’t get any at all :(

how do leks form?

• hotshots: some younger/ less successful males cluster around better males to learn from them

• hotspots: females congregating in specific areas for some reason

give an example of a variable mating system:

Dunnocks:

• depending on environment, dunnock can show: monogamy, polygyny, polyandry, or polygynandry (multiples of each sex)

• there’s an underlying structure to what is switching between these

• sex is established independently with generally overlapping territories in relation to prey abundance

  • when food is dense and male overlaps with one female vs many → monogamy vs polygyny

  • driven by environmental resources

give an example of a species that takes EPC’s to the extreme

Purple Martins

• colonial nesters

• older males tend to arrive first on breeding grounds, will establish nest with a mate

• will then attract later arriving younger males to colony with a special song (low rent)

• young males will establish nest with mate of their own, then older male will come in and mate with new females (cuckolded)

• primary males have an average of 3.5 eggs with original female

  • gain an additional 3.6 eggs from mating with other females

  • very good fitness increase for the primary male

• only ~30% of eggs in colony are from younger males → fitness lost

what are the two primary modes of reproduction?

sexual / asexual

what are the costs of sex?

• can reduce your own genes through recombination, adaptive gene combinations

• costs of sex is essentially cost of males

  • presence of males = reduction of reproductive success for females

  • in a population of 3 individuals with male and female reproducing sexually and single female reproducing asexually:

    • reproductive potential is higher in the singular female

    • sexual female has half as many grandchildren as asexual female

explain Muller’s Ratchet:

*if you are reproducing asexually, the genetic makeup of offspring is not exactly the same - some alleles may be deleterious

• Muller’s Ratchet explains why sex makes sense in regards to deleterious mutations

  • if you’re reproducing asexually (starting with no deleterious mutations), over time mutations will build up → eventually leads to mutational meltdown

  • if sexually reproducing, you can potentially avoid mutational meltdowns

explain post pathogen evolution:

*pathogens try to kill their hosts*

• if asexual: the response is to just die

• if sexual: red queen hypothesis

  • as the parasite of a pathogen is trying to take over your system, your system will try to find a way around the pathogen

    • in turn, the pathogen tries to find a way back around this

  • called red queen because both species are running forward, while staying in place (like alice in wonderland)

• parasite’s genetic ability to change rapidly beats down defense of the host

• if female has the opportunity, they should seek EPC’s to maximize the potential of her offspring surviving

why does sexual dimorphism and male trait elaboration exist?

• males are producing lots of small gametes while females are producing comparatively fewer and larger gametes

  • competition between sexes in regards to sexual selection strategy

  • females “lose” if they poorly select mate → more choosy in selecting mate

• systems can work by males competing with each other, or females making the choice

what are the 2 hypotheses as to why females choose males with fancy traits?

1. good genes

   • exaggerated traits are truthful signals of genetic quality

     • females may recognize this and select superior males to sire offspring

   • if you have the most elaborated traits, you have the best genes

   • you wouldn’t be able to produce these traits if you weren’t a healthy individual

   • these traits may be a potential handicap to survival

     • ex) long tails not efficient for flying, only for sexual selection purposes

   • evolution should seem to favor bigger and bolder badges of a handicap if female prefers them

   • bright colors attract predators, but could also signal parasite load

     • males with more vibrant colors typically have fewer parasites

   • sexual selection →← natural selection

     • traits can only become so big before natural selection decides they are too big

2. arbitrary choice w/ runaway selection

   • suggests that there is an arbitrary preference from females for male traits

   • may have evolved to extremes

   • some links to “good genes” hyp.

what are the 2 models for sexual selection?

model 1: males compete for access to females (intrasexual selection)

• males monopolize females

• males engaging in contests to determine which male gets access to females

• females are NOT choosing → intrasexual selection

• successful male can monopolize lots of females and potentially mate with many of them

• most extravagant trait usually wins the contest: females don’t necessarily prefer this trait, but since it always wins - they end up mating with it

model 2: females choosing (intersexual selection)

• females choosing among males on the basis of the state of one or more features on display

• in this case, males advertising to females, the one with the most elaborate display is preferred by females

explain and give an example of sperm competition

sperm competition occurs when the sperm of 2 or more males have the opportunity to fertilize a female’s egg

• very subtle form of intrasexual selection

• usually seen in polygamous systems

  • female copulating with multiple males

• males enhance the chance of fertilization by producing more sperm

  • if two males are fertilizing a female, the one with the bigger sperm contribution is most likely to “win”

  • explains why polygamous species have larger testes than you would expect from body size alone

• lots of variation here: sometimes first sperm in is the one to fertilize the egg, sometimes it’s the last sperm in, kamikaze sperm can block other sperm from being able to fertilize the eggs, sperms can put up barriers to trap themselves in females

ex) mallards have antibacterial ejaculations that relate to bill color (more yellow bill = more antibacterial resistance, better quality jizz)

give an example of a study that demonstrates female choice:

Møller’s Barn Swallows:

• barn have concave tails with flight displays

• males will defend a territory and then attract females for breeding

• in this system, males are larger and generally more brightly colored than females (sexual dimorphism)

• most prominent feature of male display: tail feathers

  • easy to see

  • male tail streamers tend to be longer than females → does this signal a female preference?

Møller color banded 44 territorial males before females arrived on breeding grounds

• divided them into 4 groups of 11 and assigned a different treatment to each group

  • 1st group: tails shortened by 2cm

  • 2nd group: tails mock altered - clipped tails and then glued back on (controlling for effect of clipping tail)

  • 3rd group: unaltered, but banded (controlling for effect of fancy band)

  • 4th group: tails elongated by adding additional 2cms

• males in 4th group mated significantly faster than other males and had higher clutch sizes (female invests more energy)

  • more fledglings leave the nest

  • not a single instance of EPC’s

• in all cases: shorter tail males had lowest fitness

  • their mates consistently seeked EPC’s

• females also selecting for symmetrical tail lengths

  • looking for males with long streamers that are equal lengths

  • symmetry suggest better genes bc they are genetically able to produce the same length tail

give an example of female choice with assortative pairs:

Blue Tits:

• both sexes have UV reflectance

• males have a purple crown patch that we can’t see, but they will display it to females during courtship

• studies of that system show that females prefer males with the brightest crown patches

• males and females are pairing assortatively

  • males with highest amount of reflectance mate with females with highest amount of reflectance, and so on…

  • males and females both prefer to choose based on rank

• benefit of female mating with brighter crown patches: color intensity predicts survivability into the next breeding season

  • males with brightest patches are genetically more heterozygous than other males

  • females increase the proportion of male offspring in their brood in proportion to the level of UV reflectance in mate (want to have sexy sons)

where is song produced?

in the Syrinx

• birds w/o syrinx can only make grunts and hisses

  • vultures, storks, ratites

• birds use 100% of air passing through syrinx - allows for incredibly complex song

  • in comparison, mammals only use 2% of the air passing through larynx

  • birds also have a larynx which is controlled by up to 8 muscles v.s. only 2 muscles in mammals

• 2 sided syrinx = more complex anatomy = more complex song

  • allows birds to “duet” with itself by singing in each independently controlled side (~20% of birds)

    • ex) wood thrush, grebes, sandpipers, ducks, many songbirds

how many syrinx muscles do songbirds usually have?

non songbirds?

• songbirds (oscines) can have 6-8 pairs

• most non-passerines have 2 pairs of muscles

how many distinct recognition calls does a bird usually have?

what are some of their functions?

each bird generally has ~5-14 distinct calls for recognition

• functions include: territorial displays, mate attraction, warning calls (like pishhing), social contact (especially in monogamous mating pairs), and broadcast of personal features (age, sex, species)

• song is something that can be selected upon

• a larger repertoire may indicate an older more experience male

  • broadcasts of large repertoires resulted in slower re-occupancy or territories

  • implies social dominance: larger repertoire = more dominant

examples:

• Song Sparrows: males with larger repertoires received more copulations

  • females selecting for larger vocabs

• Common Canary: females respond to large repertoires by building nests faster, laying eggs sooner, and laying larger clutches

  • implies that males with larger vocabs may be more successful, or more pair bonded to females laying eggs in the territories

give an example of intrasexual competition in regards to song

give an example of intersexual competition

intrasexual competition: (same sexes)

• vocal dueling for territories and mates

  • marsh wrens

intersexual competition: (between sexes)

• advertising to unmated females

• more polished songs and larger repertoires are typically selected for

  • mockingbirds

give an example of song including information about location:

male chestnut-sided warblers:

• have different song types and aggression levels depending on where they are in their territory

• when singing in center of territory:

  • angry aggressive calls

  • projects over the widest range of the territory

• when singing close to another territory:

  • doesn’t wanna piss off other male and compete for resources

  • will sing a quieter, less aggressive song

• when singing in intermediate zone:

  • intermediate song

  • aggressive and less quiet so they can attract females

• trying to find the sweet spot between attracting females and keeping other competing males away

what are “floaters”

give an example of a study done with holders and floaters:

waiting around for a new territory to open

• if territorial presence is not regularly advertised by song, a new occupant will move in quickly

Great Tits (studied by Krebs in 1977)

• studied 2 groups: holders and floaters

• territory holder needs to be singing fairly regularly to keep floaters away

• if there was lots of floaters in the area and Krebs played an aggressive song from speaker → territory holder would leave

  • even though territory holder was established and defending from floaters

  • suggests that floaters may be going around trying to win over other’s territory

give an example of song being used for individual recongnition:

• helps colonial birds recognize pairs

ex) Emperor Penguins have extremely distinct calls

• paired individuals will respond quickly to their mate’s signature, but not to others

why duet? which birds probably won’t do this?

duetting is practiced in birds with long-term monogamy that defend year-round territories

• migrants probably aren’t going to spend the time dueting

• males and females not together year round

• migration is a derived trait in birds, deriving this trait loses vocal duetting

what is the “audience effect”? give an example

audience effect: more competition for attention drives strong bonds and duets

• males with smaller territories may sing more aggressively

zebra finches:

• song becomes more rapid and louder when close to other pairs

give examples of different ways birds learn to sing:

songs can be inherited, learned, or invented:

• young cowbirds raised by another species still sing normal cowbird songs (inherited)

• eastern meadowlarks inherit call notes, but learn songs (from dad and others during breeding season)

• thrashers and mockingbirds can learn new songs their entire lives

what are the 3 periods in which early learning occurs?

1. sensory acquisition:

   • critical learning period: info stored for later use, lasts 10 days to 1 year

   • silent period: where songs learned in critical learning period are stored without practice (up to 8 months)

     • white-crowned sparrows deafened during this silent period never learned correct song

2. sensorimotor learning:

   • like when a baby is trying to talk - babbling

   • subsong: a period of practice without real communication

3. song crystallization:

   • song is transformed into stable, less plastic patterns

   • happens at end of practicing period

   • now has the muscle and brain memory to keep up with song

   • song is set in stone, for life

learning requires feedback, what are the two different types of learners?

1. open-ended learners:

   • learn new songs throughout their lives

   • can change song fairly rapidly

   • mimics: trashers, mockingbirds, corvids

2. age limited learners:

   • can only learn songs during a certain period of time

     • ex) white crowned sparrows - once past silent period, only need to crystallize song

     • age of cutoff varies by species

     • “can’t teach an old dog new tricks”

what are some theories as to how dialects arise in birds and why song may differ geographically?

1. new songs can arise as new areas are colonized

   • essentially geographical speciation

   • certain song that a group of colonizers are most associated with becomes the new most dominant song

   • young learn songs from their fathers, more successful fathers = more kids carrying your song into the next generation

2. social focus shapes the patterns of local variation

   • young birds could increase reproductive success by imitating older successful birds

     • ex) black-throated blue warblers

3. ecological hypothesis:

   • dialects influence the genetics of local populations

   • dialects genetically passed down and selected for across generations

simple explanation: differences in dialects exist because learning is not perfect and birds have individual variation in their songs

give an example of a bird with lots of variation in its song dialects

Swainson’s Warblers in Lick Creek:

• lots of overlap in breeding habitat with hooded warblers

  • young swainson may have been nesting near a hooded warbler and picked up on aspects of his songs

• Swainson’s warbler song sounds has a very sweet, fluid sound with crisp ending ; roughly 7-8 notes

• Hooded warbler song sounds a little sweeter, more bouncy, less fluid ; roughly 5 notes

• Swainson’s Warblers in Lick Creek have fluidity and tone of swainson’s but the song pattern from a hooded warbler

  • shows that song learning isn’t perfect

why do songbirds in temperate regions tend to have male-only song, while tropical regions often have females singing elaborately and defending territories?

theories:

1. females must maintain their own territories in the tropics (barred antshrikes will sing more often than males)

2. singing is an ancestral trait shared by both sexes

   • migratory species lost this because they were focused on resource use

3. tropical species may have less visible sexual dimorphism

   • song needed to distinguish males from females

why do birds sing in the morning?

why do some birds sing at night?

• sound may carry further in dry, morning air

  • less light = more camo from predators when singing from the top of a tree

  • “early birds” may be more fit

• nocturnal-foraging birds sing when conspecifics are most active

  • singing triggered by light: light pollution and full moons may trigger singing

  • anthropogenic change leads to adaptation: urban blackbirds in europe sing at night - potentially to avoid noise pollution

what is the heterogametic sex in birds?

what does this mean (think chromosomes)

females are the heterogametic sex

• inactive “w” chromosome + 1 “z” chromosome

• males have 2 “z” chromosomes

what causes an embryo to be half male half female?

barren mitotic division

• testes on one side, ovaries on the other

• sharp plumage division

• small female side, big male side

bilateral gynandromorph

what activates reproductive behavior

gonadal secretion of testosterone / estrogen

explain the acquisition of male breeding plumage (secondary sex characteristics)

how do we know this?

the result of increasing amounts of testosterone:

• we can prove this by castrating males -

  • castrated individuals do not acquire secondary sex characters like waddles

  • female phalaropes have higher testosterone levels than males (means that females are more brightly colored)

• response from feather molecules to luteinizing hormones are responsible for colorful breeding plumage in males

  • estrogen inhibits any effects of luteinizing hormones in females

what is typically the main determinant of offspring viability?

give an example of manipulation of clutch sexes:

egg mass and laying/hatching order

• egg mas also related to female condition

  • in yellow-legged gulls, relatively large, last laid eggs are most likely to carry a female embryo

    • suggests that mothers are trying to allocate extra resources to daughters in last-laid eggs

    • if its a daughter, mom will increase the amount of energy put into the egg

  • manipulation of clutch sexes also seen in tits

give an example of a tradeoff made by females regarding hatching investment

blue birds:

• tend to lay multiple sets of eggs within a season

• studied association between female condition (age, body condition) and prehatching investment (clutch size, egg mass per clutch, total clutch mass)

• in 2003, females that were heavy relative to their body size laid bigger eggs and invested in overall clutch mass (consistently big eggs)

• in 2004, females who laid heavy overall clutches in the first season, laid proportionally smaller second chicks

overall clutch mass likely represents a significant cost to females

• although second clutches tended to be smaller in the number of eggs, the mass of each egg remained the same

  • doing this suggests an allocation of resources to help late season offspring survive better

  • laying 3 bigger eggs instead of 5

give an example of cue processing having an effect on reproductive success

dutch population of tits studied since 70’s:

• reproductive success is dependent on how well pairs are matching the time of when they have nestlings to the seasonal peak of abundance of caterpillars which they use to provision their offspring

  • lay eggs 2-3 weeks prior to caterpillar peak

• over the last 20-30 yrs, temps have gotten hotter in spring and made it harder for tits to track advances in caterpillar peaks

• driving a selectional differential: some individuals able to respond to this difference better than others

what is the correlation between sperm velocity and EPC’s

what abt sperm velocity and clutch size?

positive correlation between sperm swimming speed and frequency of EPC’s

• study looked at 42 species in 16 families

• EPC’s used as a proxy for reduction of competition

negative correlation between sperm swimming speed and clutch size

talk abt variations in egg shape and color

egg shapes and color are highly variable

• cavity nesters tend to lay white eggs - eggs don’t need camo bc they are in holes

• costly to add porphyrins to color eggs

some Alcids (like common murre) lay almond shaped eggs to protect them from rolling off cliffs

what is the biggest factor impacting clutch size?

availability of resources for egg

• if female lays a big clutch in early part of year, next clutch will likely be smaller

• clutch size variable between and within species - usually 4 in shorebirds (determinate layers)

how many developmental stages does an embryo undergo between

development → hatching

42 stages

• first 33 stages pretty much the same across species

• other 9 are specialized characteristics - species specific feathers

• latter stages can be prolonged or shortened

  • shorter in precocial species

how do chicks break out of the egg?

chick must position itself in a way that increases efficiency of breaking the shell and through to other side

• basically pecking at the blunt end of the shell while slowly rotating itself in a counter clockwise direction

  • after a day or 2, a circular fracture outline appears on the shell and the chick can exit

what are the two transient morphological features that help chick get out of egg

1. hatching muscle on back of neck

   • provides power for pecking

2. calcified egg tooth at tip of bill

   • helps them crack through shell

• most features lost soon after hatching

• songbirds reabsorb their egg tooth for calcium

• woodpeckers carry egg tooth until leaving the nest

  • egg tooth is highly reflective in the wavelength that woodpeckers see in

  • cavity nesters - egg tooth helps parents find kids

what is the big exception to egg tooth?

megapodiidae

• after a fairly large hole is made, some parents will help out

• male ostrich will yank chicks out of the eggs (he is the one incubating)

what happens to the egg shells in nest after chicks hatch?

usually removed immediately after hatching to protect nest camouflage

• may eat it, feed to chicks, or remove entirely

Timbergen: “father of avian behavior”

• found that removing egg shells from herring gull nests, reduced crow predation from 65-22%

what are the two different ways a clutch can hatch?

give an example of each

1. all at once (synchronously)

   • incubation starts at the same time for all eggs

   • hatching synchrony due to rate of development - later eggs develop faster

   • vocal communications between chicks in eggs helps them time hatching

     • older chicks abt to hatch make a clicking noise (~60x / sec), causes younger chicks to accelerate hatching efforts

     • if they aren’t ready, younger chicks will click more rapidly (~100x / sec), telling older chicks to delay hatching up to 33 hrs

     • bumping into adjacent eggs encourages leaving

   • highly synchronized hatching is a feature of ducks

     • mallards will lay a dozen eggs btwn a week period, but all of them will hatch within the hour of each other

2. over a few hrs or a week (asynchronously)

   • result of incubation being started before the last egg is laid

   • seen in raptors

what is significant about embryonic metabolic rates?

developmental rates showed that embryos laid later in the clutch had higher metabolic rates that eggs laid earlier in Canada Geese

• yolk reserves at hatching were lower in later laid eggs (burning more resources)

• typical of precocial birds

give an example of a learned behavior:

• hatchling herring gulls learn to peck at bright red spot on adult’s bills to receive food

  • innate response causes them to peck at red spot

  • accuracy becomes refined w/ age + practice

  • hatchlings respond better to a red knitting needle than actual bill of a gull

• young birds learn abt dangerous species by watching older birds mob them

  • “pishhing” draws in kinglets, vireos, chickadees, etc… they’re trying to figure out wtf is going on

what is imprinting?

special kind of learning that occurs during critical learning period

• learning during this period can’t be forgotten

• determines habitat preferences, shrike behaviors (impaling prey), mating preferences, etc..

• combination of movement and sound reinforces what a parent is

what role do thyroid hormones play in imprinting?

• preference for imprinting on certain objects can be blocked w/ hormone blockers

• ducks will imprint on objects @ 14 hrs old

  • moving objects that they follow within the first 24 hrs controls their relationships with other ducks

  • ducks have imprinted on moving shadows or moving box w/ a ticking clock (need some kind of sound)

differences between altricial and precocial birds:

(super precocial, precocial, sub precocial, semi precocial, semi altricial [2 categories], altricial)

Super Precocial:

• down, sight, mobility, don’t need parental nourishment, parents are NOT there

• ex) megapods

Precocial:

• down, sight, mobility, no parental nourishment, parents are there

• ex) ducks, chickens

Sub-Precocial:

• down, sight, mobility, some parental nourishment (could be Y/N), parents are there

• ex) grebes, rails, cranes, loons

Semi-Precocial:

• down, sight, sometimes mobility (Y/N), parental nourishment, parents are there

• mobile, but stay in nest

• gulls, terns, penguins

Semi-Altricial (2 categories)

1. down, sight, not mobile, parental nourishment, parents are there

   • ex) herons

2. down, NO sight, not mobile, parental nourishment, parents are there

   • ex) owls

between altricial and precocial, which has larger egg and yolk size?

precocial has larger egg and yolk size

between altricial and precocial, which has the larger brain at hatching

precocial birds have larger brains

• brain continues to develop in altricial birds

between altricial and precocial, which has a larger small intestine

altricial birds have larger small intestines

• processing different foods, more variety

• faster growth rates (3-4x faster)

what was the original (primitive) mode of development?

precocial

• found in a lot of primitive birds

what is the primary advantage to being altricial?

specialized nutritional adaptations that require food delivery from parents

• must be able to fly to get prey items

• learning of feeding skills

• necessary for the evolution of a larger adult brain

• brain of altricial birds differentiates much quicker than precocial birds

what is the purpose of siblicide?

give examples of species that do this:

in some species, sibling rivalry can play a large role in whether or not a chick makes it to fledging

• larger siblings can bully nest mates and monopolize food, puts younger chicks @ risk

standard method of brood reduction in herons and eagles

• second egg is laid as an adult reproductive success buffer (just in case something happens to the first chick)

• in eagles and herons, the first chick will almost always kill later hatchlings

  • in one eagle species (200 nesting records), only one case did both chicks make it out of the nest

  • great egret first hatchlings often kill their nest mates

    • seems to be tied to the ability of the older chick to monopolize the small fish that parents are bringing back to the nest

  • great blue heron chicks do NOT practice siblicide

    • parents bring back larger fish that they then rip into pieces - can’t be monopolized

  • if you take great blue heron chicks and but them in great egret nests, they start practicing siblicide

    • if you take a great egret and put it in a great blue heron nest, they still kill each other

      • deep seated behavior/desire to kill everyone

give examples of feeding rates varying widely among species

• once a day in albatrosses

• once a minute in some small passerines

• records of nearly 1000 food delivery trips in a day by a house wren

what kind of things can influence food delivery rates?

• delivery rate increases as chicks get older bc chick needs more food

• feeding rate and success at acquiring food from a parent is often influenced by begging

  • parents increase feeding rates substantially if begging calls are artificially played back

  • the loudest chick usually gets the most food

    • some species prefer to feed to runts

• visual cues in chick’s mouth can enhance feeding - act as a target or prevent brood parasites

give an example of a bird that invests a substantial amount into parental care

• rearing of penguin chicks consumes ~30% of adult’s annual energy budget

  • substantial cost of parental care favors biparental care from monogamous mates

give examples of dual parental care

• seabirds: both parents needed to account for extend dangers of feeding absences

  • one parent needs to stay behind to watch chick while other grabs food

• raptors: single adult can’t spend much time foraging - eggs need to be at a constant temp and protected from predators

  • one parent forages while the other incubates the egg

• 211/250 passerine species - male feeds mate in incubation

  • in cases where males weren’t feeding females: it was bc of nest position and potential for eggs to stay warm via sunlight (mom doesn’t have to stay on eggs)

explain the trade off between survival rate of chicks and cost of parental survival / additional mating opportunities

• parents want to get kids to the point where they are on their own as soon as possible - increases the time left for additional mating opportunities

• young trying to maximize and monopolize parental attention for as long as possible (don’t wanna leave nest)

example of a study that examined relationship between past investment and expected benefits

Winkler - did a long term banding study on Tree Swallows

• had a bunch of clutches of 5 eggs

• reduced clutch size from 5 → 3 eggs in some nests

  • caused 3/14 parents to renest

  • 11 stayed on nest

• reduced from 5 → 1 egg in other nests

  • 19/19 abandoned the nest

  • 14 of these pairs went and set up a new nest w/ 5 eggs

• suggests that there is a tradeoff between current potential success and future success

what are the 2 forms of brood parasitism?

1. intraspecific: female of species A lays egg in nest of another female of species A

   • rate of parasitism increases when nest sites are few and population density is high

2. interspecific (obligate): species of A is ALWAYS going to lay her eggs in the nest of species B

   • never build a nest or have contact with progeny

   • evolved independently in at least 7 different families

     • not all species in family are obligate (cuckoos, icteridae)

   • eggs require 2-4x less incubation time than host species

     • allows parasite chicks to push out others and monopolize food resources

   • some obligate brood parasites are highly specialized

     • use a few or just one primary host

     • other obligates lay eggs in nest of many different species (cowbirds)

give an example of intraspecific brood parasitism:

• widespread and prevalent in waterfowl (nests need to be clustered)

• rate of parasitism increases when nest sites are few and population density is high

  • ex) in densely populated cliff swallow colonies with at least 10 pairs, 25% receive eggs from other females

• female who owns the nest suffer reduced fitness

  • female goldeneyes generally lay 12 eggs. if parasitized early in egg laying, they will include any foreign eggs as part of their preferred clutch size of 12 (losing fitness)

• evolutionary arms race in starlings: females will eject any egg from their nest that was laid before they themselves begin to lay

  • once they begin laying, they stop doing this bc they can’t distinguish between parasitic eggs

  • lonely female starlings will toss one of the host’s eggs prior to parasitising nest (makes it less detectable while keeping clutch size to the optimal 6)

  • starlings generally lay 5 eggs despite 6 being optimal (best course of action for females in situations with high prob of being parasitized)

what is the big problem with obligate brood parasitism in cowbirds?

cowbirds lay eggs in nest of 450 different species

study done on small forest fragments in illinois found that cowbirds parasitized 75% of the nests of neotropical migrants

• size of fragments is critical - makes it easier for cowbirds to parasitize

• forests cut down for tree farms (logging) → roads put in → more edge habitat for cowbirds

  • many smaller forest patches now have active cowbird reduction problems (big problem for golden-cheeked warblers)

what are some defenses that have evolved to protect against brood parasitism?what about the counter defenses that come from parasites?

• chicks have evolved elaborate markings in mouth (parent can look for a specific pattern when feeding)

  • parasites have evolved same markings

• parasites will mimic egg shell patterns, songs/calls, and even juvenile plumage of host

give an example of a species that has a lot of variation between the rates of brood parasite rejections:

• southern robins regularly reject cowbird eggs

  • cowbirds have been around in the south longer, southern robins have learned to adapt

• northern robins generally accept cowbird eggs

  • haven’t adapted yet

how do we know that bluebirds are using visual cues to detect brood parasites in their nest?

eastern bluebirds are currently subject to relatively low levels of interspecific brood parasitism from house sparrows

• tested the visual cues bluebirds were using to eject foreign house sparrow eggs from nests

• house sparrows lay eggs that are an off-white brown color with brown speckles

to test which colors/patterns were allowing bluebirds to discriminate between eggs: they 3D-printed house sparrow eggs and painted them either: entirely off-white, entirely brown, half white / half brown, or off-white with brown speckles

• 4 different eggs placed in each nest over the course of 4 days (every nest is getting each type of egg)

• after watching females enter and leave the nest box just one time after placement of model eggs → speckled eggs were rejected 50% of the time

  • in all other treatments, 3D egg was not ejected

reveals that eastern bluebirds are able to recognize speckled egg patterns as brood parasites, but not anything else

• only recognizing a very specific pattern unique to house sparrows

give an example of a species that practices cooperative breeding:

Florida Scrub-Jays: nest in florida scrub habitat (not lots of it left)

• breeding pairs with helpers fledge more chicks

in 200 helper cases recorded over 9 yrs:

• 59% helped both parents

• 25% helped one parent

• 16% helped distant kin as well as nonkin

• Western Scrub-Jays do not help each other out (habitat range is not saturated)

White-fronted Bee-eater: lack of rain during month preceding breeding results in an increase in the % of population that helps others

• rain triggers bugs, less rain = less bugs = less resources

Groove-billed Anis (intraspecific)

• form social units of up to 4 pairs

• females of these paris lay eggs in communal nests (share costs of night nocturnal predation rates and improves individual survivorship)

• 2 or more females in a situation (finite amount of space in nests) - each female begins trying to toss out eggs of others

what are the benefits to cooperative breeding?

based on helpers helping genetic relatives, helpers are capable of breeding, but choose not to:

• by helping relatives, they gain indirect fitness

• saturated habitat drives cooperative behavior

• younger birds can’t set up own territory, but if they help another bird, they could potentially take over the territory later on

• not an altruistic behavior to help nonkin because they are hoping to get territory

what is disease ecology?

interaction between pathogens & parasites and their hosts

what are possible parasites of birds?

bacteria, worms, ectoparasites (lice), mites, biting flies

what are possible pathogens of birds?

avian pox, trypanosomes, west nile virus, avian malaria

what continues to be an increasing problem with respect to zoonotic diseases?

give an example:

invasive species, climate change, anthropogenic changes all destabilize host-pathogen interactions

• climate change expands breeding season of avian malaria

• as temps warm → increased rate of parasite development and altered seasonality of transmission

Loons: parasites starting to show up in alaska, iceland, antarctica

• climate change allowing parasites to expand range

what are some costs of having a parasite?

• competition between parasite and host for resources

• energetic costs for hosts to defend against parasites (ex: grooming)

• costs to develop and maintain resistance to parasite

• tissue injuries - either directly from parasite, or inflammatory / immune responses

  • costs to repair damaged tissues

• improper development of organism bc of parasite

• benign infections, acute infections, death (potentially)

how does the allocation of energy change when a bird is being parsitized?

* the amount of energy available is not constant or uniform, varies seasonally, with weather, habitat, and number of competitors *

non parasitized: majority of energy going towards maintenance, then production, then fat reserves

when parasitized: majority of energy still going towards maintenance, then defense / immune response, then production

• no longer has the energy to keep up fat reserves

what are some mechanisms that allow persistence of pathogens in avian migrants?

• crowding at breeding sites

• stress of migration can trigger latent infection or increase susceptibility of new ones

• spillover at migration stopovers and destinations increase chances of transmission

birds likely transmitting diseases from S → N

explain the lifecycle of avian malaria

1. mosquito bites a bird

   • picks up the plasmodium parasites in the bird’s blood

2. parasites develop in the mosquito

   • eventually move to the mosquito’s salivary gland, ready to infect another bird

3. mosquito bites a new bird

   • injecting parasites into bird’s bloodstream via saliva

4. parasites invade the bird’s cells :(

   • when another mosquito bites this bird, the cycle restarts

elaborate on epizootiology and ecological significance of malaria on hawaiian land birds

before 1826, no native mosquitoes in hawaii - researchers set up sampling sites to find where malaria was being distributed

• endemic birds are naive hosts - parasite able to effectively exploit them (many species went extinct)

  • non-native populations were not hit as hard (already developed the defenses against malaria)

• surviving species had broad distributions → mosquitos can’t reproduce above 1500m

  • resulted in major shifts in elevational distributions of highly susceptible native forest birds (no more native birds found @ lower elevations)

how does malaria impact the way resources are distributed amongst clutches

Blue Tits have asynchronous broods:

• nesting populations screened for infections

• anti-malarial drug given in control, low, med, and high doses (high doses clear infections)

• clutch data taken, chicks weighed and measured until fledged

if female is infected and then cleared w/ a high dose of magic drug:

• they will distribute resources unevenly (clutch becomes more similar in size)

  • able to redistribute resources that would otherwise be used to fight off infections

  • now have the energy to feed runts

• medicated females had higher hatching success, increased provision rates, and overall fledging success

elaborate on a study done on Eleanor’s Falcons that demonstrates the prevalence of avian malaria parasites between phenotypes

• migratory species need to run through a gauntlet of Eleanor’s Falcons

  • falcons will wait to have their kids until migration starts

• dark morphs had a higher prevalence for plasmodium parasites than pale ones

  • associated not detected in Haemoproteus

  • could be from unequal exposure to vectors

• shows that there is a differential ability for some individuals to mount immune response against blood parasites (pale ones may have genes that give plumage color PLUS immune response)

what are pleiotropic effects?

one gene that can influence 2 or more unrelated traits

what are the 3 genera of malaria parasites?

1. plasmodium (mosquitos)

2. haemoproteus (biting midges)

3. leucocytozoon (black flies)

how do the ecological constraints of malaria differ across sub-saharan africa?

all three parasites live in Sudanian region

• each parasite requires a different level of moving water

• no midges in South African range, barely any in congolian region

• most endemic species of birds live near the tropics (Zambezian, Congolian areas) - most naive hosts

what groups of avian hosts are the most susceptible to infections

weavers: nest are close to one another → makes transmission easy

sunbirds: share a resource (nectar) w/ parasite (mosquitoes)

what happened in Sardinia in regards to avian disease?

in Sardinia, there are a very high number of sedentary species with unique haplotypes

• probably bc there are lots of unique parasites that impact these sedentary birds

• after WWII, shitload of DDT was dumped on Sardinia (wiped out all the parasites)

  • anything that survived was able to diversify quickly - becoming a unique population on the island

• ended up creating more lineages of malaria and made a bigger problem