Lecture 20- Australian Birds II

Question 1

What is convergent evolution?

Answer 1

-evolution of similar features in unrelated species
-many Aust species resemble northern hemisphere spp.
-• DNA studies allow origin and evolution to be unravelled
• proves that these Aust birds not derived from northern hemisphere stock - more closely related to each other than to N.H. “look-alikes”

Question 2

What are exampled of convergent evolution?

Answer 2

-english robin= aussie robin
-english wren=aussie wren
• these examples illustrate convergent evolution, not taxonomic relatedness
• Most Aust spp. are corvids, descended from ancestors of crows

Question 3

What types of mating systems are there in birds?

Answer 3

• monogamy • polygyny • polyandry • promiscuity

-Usually strong association between mating system and level of parental care

Question 4

What is monogamy?

Answer 4

• one male with one female
• pair bond lasts for between one season and a lifetime
• mate, incubate and raise chicks together
• most widespread pattern

Question 5

What is monogamy in albatrosses?

Answer 5

• single chick takes up to 280 days to reach independence
• parents take turns to undertake long foraging trips
• demands of chick rearing favour monogamy
-life-long bond between the pair
-have to feed the chick for a long time, so the input from parents is high
-the albatrosses forage over massive areas
-if one of the pair dies, then they never pair up with anyone else

Question 6

What is monogamy like in black swans?

Answer 6

males and females pair for life (social pairs)
• about 15% (1 in 6) cygnets are ‘illegitimate’
-so the pairing is mostly social for life but not neccessarily genetic

Question 7

What is monogamy like in fairy-wrens?

Answer 7

• males & females pair for life
• both parents care for young
• males show a variety of adaptations for ‘extra-pair’ mating
• 76% of all offspring are ‘illegitimate’
-Monogamy is social, not necessarily genetic
-philandering in fairy-wrens

Question 8

What is polygyny?

Answer 8

• 1 male mates with several females
• Males often have elaborate coloration and courtship e.g. riflebirds
• or males build structures + exhibit courtship e.g. bower birds
• Generally no male contribution to care

Question 9

In which birds do we have polygyny?

Answer 9

-bowerbirds

Question 10

What is the breeding like in the Satin Bowerbirds?

Answer 10

• Males build ‘avenue bowers’ and decorate them with blue objects
• Females tour bowers during the breeding season
• Females decide whether or not to mate after judging bower - “mate choice”

Question 11

What is polyandry like?

Answer 11

• 1 female mates with several males • separate clutches for each male • may be ‘successive’ or ‘simultaneous’ • male raises offspring

Question 12

What is the breeding pattern in Southern cassowary?

Answer 12

-Successive polyandry

• female lays for up to 3 males • male incubates 2 months • extended male care: 9 months

Question 13

What are the forms of parental care in birds?

Answer 13

• bi-parental
• paternal or maternal
• mound-builders (care during incubation)
• cooperative breeders (the whole family)
• no care

Question 14

What is bi-parental care in birds like?

Answer 14

-(monogamy)
• Chicks are raised in underground burrow
• Male and female alternate shifts during incubation and feeding

Question 15

What is parental care like in emus?

Answer 15

-Paternal care: emus
• successive polyandry
• female lays 5-15 eggs
• male incubates clutch for 55 continuous days
• continued care of young for up to 6 months

Question 16

Which birds are the mound builders?

Answer 16

• Family Megapodiidae: SE Asia-centered distribution

* 3 species in Australia: malleefowl, brush turkey, orange legged scrub fowl

Question 17

What is the breeding like in Malleefowl?

Answer 17

-mound builders
• eggs laid inside a mound • rotting process incubates • male maintains mound @33oC
• chicks independent at hatching (no further care)

Question 18

What is cooperative breeding?

Answer 18

• breeding pair assisted by ‘helpers’ in the care of young
• helpers are usually grown offspring from previous broods
• help with territory defence, incubation and nestling feeding
• altruistic behaviour?

Question 19

Why do the helpers stay in cooperative breeding species?

Answer 19

• shortage of breeding territories and/or mates forces offspring to stay at home
• several possible benefits:
– gain breeding experience (and possibly matings)
– indirectly pass on ‘own’ genes by helping parents raise more brothers and sisters

Question 20

Which birds have cooperative breeding?

Answer 20

choughs and apostlebirds
• live in groups of 2-20 individuals
• difficult foraging niche (sub- surface invertebrates)
• slow transition to independence for young
• acute dependence on helpers:
- nesting pairs and trios always fail - groups try to kidnap helpers!

Question 21

What are the no parental care systems?

Answer 21

1. Inter-specific brood parasitism – female drops eggs into nests
   of “host” sp. e.g. cuckoos
2. Intra-specific brood parasitism – female lays eggs into nests
   of same sp. e.g. swallows, coots etc

Question 22

How do Australian cuckoos breed?

Answer 22

• cuckoo adds an egg to the clutch of the ‘host’
• cuckoo chick develops more quickly and hatches earlier than host chicks
• cuckoo ejects the host eggs & is fed by host

Question 23

What is the relationships between fairy wrens and cuckoos?

Answer 23

-evolutionary arms race
• Horsfield’s bronze cuckoo lays a mimetic egg that tricks fairy-wren into accepting it
• in response, fairy-wrens have learned to recognise and reject chicks

Question 24

What are the two main functions of bird songs?

Answer 24

• territory defence • mate attraction
(mostly males sing)
Australian themes:
• female song • duets • vocal mimicry

Question 25

What is duetting in eastern whipbirds like?

Answer 25

• live in dense rainforest in SE Australia
• male & female sing coordinated duet
• experiments suggest duets are signals of conflict rather than cooperation
• female attempts to ‘sabotage’ male’s song

Question 26

What is the female song in fairy wrens?

Answer 26

• experiment: play back female songs to females and males
• males didn’t react to female songs (mate attraction function unlikely)
• females able to tell difference between ‘neighbours’ & ‘strangers’
• female song in fairy-wrens is probably for territory defence

Question 27

What is the bird song in the superb lyrebird?

Answer 27

Vocal mimicry: male superb lyrebird 80% of songs mimic ‘natural’ and mechanical sounds

Question 28

What are the conservation concerns of birds?

Answer 28

• Clearance for agriculture • Grazing
• Altered fire regimes • Predation
• Direct exploitation - hunting
- bird trade

Question 29

What is the Illegal pet trade like?

Answer 29

• Burgeoning parrot trade
• High return/low risk for traders
• Also trade in eggs

Question 30

What is the importance of customs in the pet trade?

Answer 30

Customs and Border Protection officers say the man was caught with 39 parrot eggs, concealed in a specially made vest, when he arrived at Perth International Airport on a flight from Bali. The maximum penalty for wildlife smuggling is $110,000 or up to 10 years in jail.

Question 31

What is the orange-bellied parrot?

Answer 31

• Critically endangered • ~ 50 individuals left in wild • Migratory species

Question 32

What are the causes of decline of the orange-bellied parrot?

Answer 32

Reports of ‘1,000s’ from 1830-1910. Most dramatic decline since 1940s, but ‘stable’ at 150-200 birds since 1980, now further decline approx. 50????
• Large scale human “reclamation” (damage) of salt marsh habitat (= winter refuge)
• Mineral exploration ,uncontrolled fires in breeding area
• Low breeding success (1.7young/nest)
• Migratory hazards (juveniles leave breeding areas later)
• Competition for food with introduced seed-eaters (sparrow, goldfinch, greenfinch) and nest hollows (starlings)
• Predators (cats,foxes) and disease??

Question 33

What are the conservation initiatives to save the orange bellied parrot?

Answer 33

• Management of habitats, especially vulnerable winter areas
• Controlled burning in breeding areas/exclusion of stock from saltmarshes to improve growth of key food plants
• Measures to control predators and competitors
• Genetic studies to manage gene pool in the wild
• Captive breeding programmes and re-introductions to wild – these have failed to improve status of wild pop.n
• Banding, monitoring and census of winter and breeding populations ongoing

Question 34

Summary:

Answer 34

• Convergent evolution • Diverse range of mating systems
• Parental care including male care, mound-building and cooperative breeding in Australian birds
• Three interesting themes in bird song: female song, duets and vocal mimicry
• Conservation threats to birds include habitat loss, predators and pet trade