Lecture 12-Cooperative breeding in birds Flashcards

1
Q

What is the definition of cooperative breeding?

A

breeding pair assisted by helpers in caring for young

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2
Q

Who are the helpers?

A

-birds of the same species, usually children from previous years

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3
Q

What are the eight cooperative families?

A
  1. babblers *
  2. fairy-­wrens *
  3. anis
  4. bee-­eaters
  5. scrubwrens/thornbills *
  6. honey-­eaters *
  7. treecreepers
  8. corvids
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4
Q

Which is the cooperative family not in Australia?

A

-anis

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5
Q

What four cooperative families are endemic to Australia?

A

-babblers -fairy wrens -scrubwrens/thronbills -honeyeaters

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6
Q

How many bird species are cooperative worldwide?

A

-3% -Australia is a hotspot

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7
Q

How many species are cooperative breeders in Australia?

A

-68 (out of 800 and when only counting the ones evolved here then that is 22% of old endemics are cooperative breeders)

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8
Q

What evolutionary history do the cooperative bird species have in Australia?

A

-all are old endemic Gondwanan in origin -no record of cooperation in breeding in recent arrivals (15-20mya)

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9
Q

What are the functional explanations of cooperative breeding? (concept)

A

-benefits that improve survival or fitness (number of offspring)

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10
Q

What are the evolutionary explanations of cooperative breeding about? (concept)

A

-evolutionary history/ancestry -common themes among cooperatively breeding species

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11
Q

What was the old idea about what favoured cooperative breeding in Australian birds?

A

-humid aseasonal climate -no migration -long life-spans -small clutch sizes -the climate: not that much support -contradicted by study showing a species of birds more likely to be cooperative when seasonal -none well supported

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12
Q

What is the monogamy hypothesis?

A

Monogamy (low levels of promiscuity) -high relatedness in family groups -helping those that share your genes can help spread your genes -favours the transition to cooperative societies.

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13
Q

What is the counter-evidence to the monogamy hypothesis?

A

-the superb fairy wren is a cooperative breeder but is the most promiscuous bird

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14
Q

Is the monogamy hypothesis correct?

A
  • on the large seems to be
  • cooperative breeding is much more common in species with low promiscuity
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15
Q

Is there a correlation in distribution of cooperative breeders and cuckoos?

A

-yes -very strong -about half of cooperative breeders are cuckoo hosts whereas only 11 percent of them are non-cooperative.

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16
Q

What sort of cooperative breeders are superb fairy wrens?

A

-facultative (some are and some not) -get parasitised by Horsefield’s Bronze-cuckoos -when the chick hatches it kicks out the eggs of the host

17
Q

Do cuckoos target cooperative breeders?

A

-YES, cuckoo chicks raised by groups of superb fairy-­wrens weigh more than those raised by pairs

18
Q

Do birds breed cooperatively to deter cuckoos?

A

YES, large groups mob adult cuckoos near their nests more than small groups -large groups of superb fairy-­wrens get parasitised less often than small groups

19
Q

Did cooperative breeding and cuckoo parasitism co-evolve?

A

-probably

20
Q

What are the two evolutionary explanations for cooperative breeding?

A

1.More likely to evolve in less promiscous species 2.More likely to evolve where there are cuckoos

21
Q

Why do helpers stay?

A

Habitat saturation or Shortage of mates

22
Q

With super fairy wrens why do the helpers stay?

A

-both shortage of territories and mates -the bigger the shortage of territories or mates(usually females) the more juveniles stay with their parents

23
Q

What is more important for staying as helpers in superb fairy wrens?

A

-create vacancy by removing a pair, later add female -helpers initially stay at home but all dispersed when female added -so shortage of mates more important!

24
Q

Why do helpers help?

A

i.Indirect benefits - enhanced production of relatives (who share your genes) ii.Direct benefits - enhanced survival or reproduction, either immediately, or in the future

25
Q

What are the indirect benefits for helpers for helping?

A

-idea of inclusive fitness or kin selection - individuals can propagate genes without reproducing -in monogamous species relatedness is high Why? Because relatives share genes parents with offspring: r = 0.5 brothers/sisters with their siblings: r = 0.5 grandparents with grand-offspring: r = 0.25 uncles/aunts with nieces/nephews: r = 0.25

26
Q

What is the cooperative breeding in purple-crowned fairy wrens?

A

-groups of 2-10 individuals, so help feed nests that are not their parents’ too -riparian specialist endemic to northern Australia -low rates of extra-pair mating(low promiscuity unlike superb fairy wren)

27
Q

Who do the purple-crowned fairy wrens help feed more (higher rate), chicks with r= 0.5 or r=0.25?

A

-r=05 -full siblings more than half siblings

28
Q

In purple crowned fairy wrens do more helpers mean more offspring?

A

-yes as they bring more food (possible alternative explanation is that the territory is that good but not the case as proved by the babblers experiment)

29
Q

How did the grey-crowned babbler experiment prove the helpers help?

A

-reduced number of helpers and the survival of chicks drops despite being in the same environment

30
Q

What is the cooperative breeding like with Bell Miners?

A

-clans consisting of several pairs and numerous helpers -helpers may help at more than one nest, differing in relatedness -within the clan, helpers help more with the related chicks than unrelated =support for indirect benefits of helping

31
Q

How do Bell miners recognise each other in their clans?

A

-provisioning calls (mew) used for kin recognition -mew calls more similar between close relatives -call similarity predicts feeding rate better than r =rule of thumb

32
Q

What are the direct benefits of being a helper?

A

-Increased survival/chances of inheriting a territory -Paying the rent -Skills and experience -Social prestige

33
Q

How does helper behaviour change in purple-crowned fairy wrens when they are the first in line to inherit a territory?

A

-normally help less with the unrelated chicks unless they are the first in line for inheritance of territory then they help more (future direct, functional benefit)

34
Q

Which birds are forced to help as “rent”?

A

-superb fairy wrens -tested by removing the helpers for a day and returning them, the dominant male beat them up when in incubation or nestlings (no effects when not breeding) -they are promiscuous so relatedness not likely to be important

35
Q

Which birds help as a way of gaining skills and experience?

A

-apostlebirds and choughs -yearling apostlebird incubate less and fees less, slowe to acquire parental skills -both are obligate cooperative breeders

36
Q

What is the breeding like in the white-winged choughs?

A

-groups of 2-20 individuals -difficult foraging niche (sub-surface invertebrates) -slow transition to foraging independence in young -extreme competition between groups (nest sabotage, ovicide) -closely related to apostlebirds -obligate cooperative breeders -reach sex maturity at 4 yrs -need to learn a lot

37
Q

Do coughs need helpers?

A

-yes -more helpers more successful nest

38
Q

Do coughs kidnap birds?

A

-yes -large groups hassle small groups -in these melees young are abducted -kidnapping appears to be a response to acute need for helpers

39
Q

What is the prestige and cheating in white-winged coughs?

A

Helping to enhance prestige and social status in the group -young birds can’t bring as much food to nestlings as adults -­ FALSE FEEDING: helpers pretend to bring food but cheat by eating it themselves -food supplementation reduced costs of finding food and cheating disappears