Lecture 20- Australian Birds II Flashcards
What is convergent evolution?
-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”
What are exampled of convergent evolution?
-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
What types of mating systems are there in birds?
• monogamy • polygyny • polyandry • promiscuity
-Usually strong association between mating system and level of parental care
What is monogamy?
- one male with one female
- pair bond lasts for between one season and a lifetime
- mate, incubate and raise chicks together
- most widespread pattern
What is monogamy in albatrosses?
• 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
What is monogamy like in black swans?
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
What is monogamy like in fairy-wrens?
• 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
What is polygyny?
- 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
In which birds do we have polygyny?
-bowerbirds
What is the breeding like in the Satin Bowerbirds?
- 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”
What is polyandry like?
- 1 female mates with several males • separate clutches for each male • may be ‘successive’ or ‘simultaneous’ • male raises offspring
What is the breeding pattern in Southern cassowary?
-Successive polyandry
• female lays for up to 3 males • male incubates 2 months • extended male care: 9 months
What are the forms of parental care in birds?
- bi-parental
- paternal or maternal
- mound-builders (care during incubation)
- cooperative breeders (the whole family)
- no care
What is bi-parental care in birds like?
-(monogamy)
• Chicks are raised in underground burrow
• Male and female alternate shifts during incubation and feeding
What is parental care like in emus?
-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
Which birds are the mound builders?
- Family Megapodiidae: SE Asia-centered distribution
* 3 species in Australia: malleefowl, brush turkey, orange legged scrub fowl
What is the breeding like in Malleefowl?
-mound builders
• eggs laid inside a mound • rotting process incubates • male maintains mound @33oC
• chicks independent at hatching (no further care)
What is cooperative breeding?
- 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?
Why do the helpers stay in cooperative breeding species?
• 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
Which birds have cooperative breeding?
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!
What are the no parental care systems?
- Inter-specific brood parasitism – female drops eggs into nests
of “host” sp. e.g. cuckoos - Intra-specific brood parasitism – female lays eggs into nests
of same sp. e.g. swallows, coots etc
How do Australian cuckoos breed?
- 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
What is the relationships between fairy wrens and cuckoos?
-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
What are the two main functions of bird songs?
• territory defence • mate attraction
(mostly males sing)
Australian themes:
• female song • duets • vocal mimicry
What is duetting in eastern whipbirds like?
- 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
What is the female song in fairy wrens?
- 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
What is the bird song in the superb lyrebird?
Vocal mimicry: male superb lyrebird 80% of songs mimic ‘natural’ and mechanical sounds
What are the conservation concerns of birds?
• Clearance for agriculture • Grazing
• Altered fire regimes • Predation
• Direct exploitation - hunting
- bird trade
What is the Illegal pet trade like?
- Burgeoning parrot trade
- High return/low risk for traders
- Also trade in eggs
What is the importance of customs in the pet trade?
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.
What is the orange-bellied parrot?
• Critically endangered • ~ 50 individuals left in wild • Migratory species
What are the causes of decline of the orange-bellied parrot?
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??
What are the conservation initiatives to save the orange bellied parrot?
- 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
Summary:
- 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
