fauna Flashcards
Australian Arid Zones
two predominant features that impact animals:
1. Climate
2. Physical geography(“shape” of land)
70% arid or semi-arid
Arid land rainfall
Arid: defined as insufficient rain for agriculture
• Arid areas <250mm
• Semi-arid areas <500mm
• Seasonality: wet & dry seasons, but timing differs in north and south
• Australia’s deserts are not the driest in the world
Rainfall count:
• Patchy: within districts& between years
• Rainfall variation in arid Aust: 10% higher compared to other arid zones around the world – e.g. Alice Springs: mean annual rainfall: 281mm, range:60-903mm!!!!
•Result: rainfall is unpredictable & thus availability of food for animals also unpredictable
Arid land climate
Extreme temperature
up to 45.0C+during day hottest recorded –50.70C
-Impacts water requirements and metabolism of animals
-Can reach freezing point at night
Arid land Physical geography
-Vast flat low areas (stony or sand), vast sand dunes & some low stony hills)
-Limited areas of ranges
-only in Pilbara and central ranges (near Alice Springs),
-all <1500m (i.e. very low ranges) c)
Landscape highly weathered:= Low nutrients: N & P
Animal survival strategies in arid zones
Challenges/constraints
- poor nutrient soils
- overall low food availability & often low quality
- unpredictable water and food supplies
- high temperatures (Jan/Feb > 40ºC)
Ecological, physiological & behavioural adaptations for animal in arid condition
Drought evasive: not active during really dry periods –i.e. dormant stage as egg or adult, develop and reproduce rapidly after heavy rains, ORmove away from drought areas
Drought tolerant: often long-lived species, tolerate very low levels of moisture & food (physiology), behavioural strategies to assist survival.
Animals in arid zones
Vertebrates:
Mammals & birds –endothermic = relatively high energy needs
Reptiles & frogs!! –ectothermic= lower energy requirements than endotherms
Invertebrates: highest faunal diversity, with ants & termites being very dominant groups -ectothermic & very small= lower total energy requirements than vertebrates.
Drought-evasive strategies: remain dormant
- remain dormant as egg or adult during dry times
Shield shrimp: dormancy in egg/cyst stage
•Cysts hatch & develop into adults very rapidly -approx. 2 weeks after rain
•Incredibly fast life cycle
•When puddles dry out, cysts in ‘suspended animation’ (diapause) for years.
burrowing frogs -dormant as adult: Cycloranaspp. & Neobatrachusspp.
•water conservation strategies:-aestivation(lower their metabolism & remain inactive)-“cocoon” (to store water)
•reproductive strategies:emerge & breed rapidly after rain
Drought-evasive strategies2. Migration to areas with water/food
Birds: e.g. budgerigars (arid zone distribution)
•behaviour: migratory/nomadic –flocks travels up to 1500km to find food & water
•Breed opportunistically when grass seeds become available after rain
Drought-tolerant strategies
- Insulate against extremes such as high temp and low water availability
- Evaporative cooling in diurnal endotherms
- =lower Water requirements and conservation
Arid zone mammals
- Endotherms, thus need to balance costs of thermoregulation with costs of water gain and loss
- Must regulate temperature (e.g. via coat colour, evaporative cooling, behaviour etc.)
- Avoid high temperatures (behaviour: nocturnal, use of burrows)
- Water conservation (physiology)
Southern Hairy-nosed wombats
-live in semi-arid zone
•Avoid high temperatures:
-spend very little time above ground (use burrows)
-nocturnal (avoid highest temps)
•Relatively inactive (radio-tracking studies)
•Relatively low metabolic rate (for a mammal)
•Survive on low quality food
“Magnetic” termites
- Ectotherms
- Mounds design reduces fluctuations in temperature
- North-South orientation
- High humidity maintained within mound
- Termites remain active during drought
honey pot ant
Honey pot ants
•Live in highly unpredictable arid environment
•Live underground (temp & humidity less extreme), emerge to forage
•Store food when it is abundant
•Special replete workers act as storage pots to feed colony
Evaporative cooling in diurnal endotherms
When air temperature exceedsbody temperature, evaporative cooling is only option
•Sweating: generally too costly (mouse would lose >20% of body mass per hour)
•Panting: primary mechanism for mammals <100kg
•Saliva spreading:wiped onto fore-limbs, subsequent evaporation cools the animal
Water requirements and conservation in arid enviroment
- Lower requirements for ectotherms
- probably no reptiles or invertebrates need to drink
- Endotherms -higher water requirements,
- but only 4% mammals, 10% birds in arid zone need to drink (i.e. adapted = arid specialists)
- Animals obtain water from foods
- insects are 70% H2O, seeds low in water, water content of other plant tissue more variable
- Arid zone animals save water using specialised water conservation strategies
Maximise access to water -thorny devil
- Specialised skin texture (morphology) to capture dew and rainwater
- Scales are surrounded by tiny interconnected channels that attract water
- Water is then funnelled from these to the mouth
Eyrean grasswren
- very efficient kidneys –assists water retention
- Don’t drink water
- Extract water from dry seeds and small insectsLong thought to b
Adaptations of small drought tolerant mammals
Fat tail dunrat •diet: insects = 70% water •low metabolic rate •torpor (saves energy) •fat storage in tail Phinex hoping mouse •diet: seeds (low in water) •minimiserespiratory water loss •very dry faeces(water reabsorbed in hindgut) •super-concentrated urine
Trilling frog
• 11-year study in arid South Australia
• Observed 150-200 frogs/ha after rain, but none in dry years
• emerge after > 5mm rain
• only 313 days in 11 yrs! Females gravid, active ~ 2 days
• egg-laying only 5 times in 11 years
• always in summer & only when rain >70mm
• successful recruitment of only 3 cohorts in 11 years!!
• very rapid metamorphosis (17 days) in shallow pools, but
can be delayed up to 9 months if ponds are deeper
Conservation issues for alpine areas
Damage due to
• Extensive recreational use
• Human infrastructure: loss of habitat, erosion, fragmentation,
pollution etc.
• Increasing frequency of fire
• Cattle and sheep (grazing and trampling)
• Feral animals – rabbits, cats, brumbies
Australian alpine zone
• 0.15% of Australian landmass – very small total area
• Mean temp. of warmest month <10oC (trees don’t thrive)
• Snow 2‐3 months per year – strongly seasonal conditions
• Strong winds
• 25% of Australia’s rainfall
• Significant area for: water supply, recreation, nature conservation
(contains unique group of native species)
-Habitat for alpine animal populations is naturally fragmented due to variation in altitude
Special features of the alpine environment:
predictable, strongly seasonal
• Extreme temperature differences
• Prolonged cold ‐ winter, night and cloud
• Permanent water & abundant moisture – high rainfall, condensation, snow melt,
• Flora mostly herbs and lichens (i.e. small)
‐ very low biological productivity
• Snow gums (sub‐alpine woodlands)
• Also some energy input from sub‐alpine areas through flying insects, wind‐blown detritus, pollen and seeds
Snow gums (sub –alpine)
- Leaves can withstand freezing (waxy)
- Do not occur on mountaintops (not in alpine zone)
- Highly susceptible to fire
Climate change and the alpine zone
Distribution of specialised alpine plants and animals is very restricted
‐ to the zone between tree‐line and summit
• As the continent warms, alpine adapted animals will have to move
higher to access preferred conditions
• Australia’s mountains are relatively low: climate change may leave specialised alpine species with nowhere to go
• Tree‐line at Mt Hotham in Victoria has already moved up 40m, to an area that had not had trees for past 25 years
• Expected 18‐66% reduction in snow cover by 2030 and 39‐96% by 2070
• With small change in temp, tops of six mountains will be the only remaining alpine ecosystems
Australian alpine zone fauna
Low species diversity
• Fewer species present as altitude increases
• No truly alpine birds ‐ migrate seasonally e.g. flame robin
• Low diversity of reptiles (only 1 species found over 2000m in altitude – Alpine skink)
• Very few mammals, largest herbivores absent
• Invertebrates most diverse and abundant group!
• All species experience highly seasonal food availability
Ectotherms in the Alpine zone:
• Lower energy requirements – useful in an energy poor environment
• body temperature declines with environmental temperatures
– Reduced metabolism and activity
• Strategies (adaptations) to avoid freezing??
– dormant life stage
– behaviour e.g. seek refugia
– migrate
Invertibrate in alpine zone
- adaptations to low biological productivity and cold
- behavioral adaptation
Tasmanian scorpionfly
- In winter consume moss – larvae only active in winter
- gather around edges of snow drifts and feed on detritus as it is released during snow melt (this is blown up from sub‐alpine areas)
- Can die in human hand – temp sensitive
Mountain grasshopper
• Small size ‐ occupy sheltered micro‐climates e.g. under rocks
• Stenothermic
– physiology adapted for a narrow range of low temps
– produce anti‐freeze!
– but sensitive to heat
• Reduced wings
– Cannot fly, or hop far…
Chameleon grasshopper
• Remain active all day (generally adapted to cooler conditions, but can cope with large temperature variation)
• Movement in & out of sun
• Thermal melanism:
‐ in cold conditions (higher altitude) darker/black, thus absorb heat
‐ in warmer conditions (hotter day or lower altitude) – paler blue or green
Corroboree frog
• Over‐winter in alpine areas (low mobility)
• Winter: become totally inactive
• Must find microhabitats that don’t freeze
• two species – northern and southern
• Occur mainly over 1800m elevation
• Males dig burrow in sphagnum moss bogs & call for mate
• Females lay in this nest
• But development is delayed until late winter, then slow.
• Snowmelt: when burrows fill with water in spring they
hatch and mature
Endothermic animals in alpine
maintaining body temp very energetically expensive in cold conditions
‐ mostly occurs in mammals and birds
Alpine endotherm strategies:
• Migratory: many sp. avoid cold by migrating ‐ e.g. birds, larger mammals (wallabies)
• Permanent residents
‐ some sp. stay active
‐ some use torpor
Torpor
- Decreased body temperature
- Reduced metabolic rate, respiratory rate, heart rate
- Curl up (minimise surface area and thermal energy exchange)
- Occurs in species where adults <10kg
- Small endotherms – high risk of starvation
- Often a response to low food availability
- seasonal and low productivity habitats
Typical pattern of torpor in small mammals
- Rapid entry into torpor ‐ metabolic rate (MR) drops, body temp drops by passive cooling.
- While in torpor MR at 1/20 ‐ 1/100 normal
- Animals exit torpor by turning MR up, body temperature follows
- Can be short‐term or long‐term
Hibernation
Seasonally‐induced deep torpor, longer bouts • Only two Australian mammals: ‐ Mountain pygmy‐possum ‐ Echidna • Fatten‐up prior to winter • Retreat to hibernaculum (= safe place when you can’t move) • Test drops in body temp • Periodic arousal
Breeding patterns in alpine zone animals
- Short period of warmer weather, thus short growing season & short breeding season, but very predictable (unlike in arid zone)
- Some species exhibit dormancy at other times of year (i.e. during non‐breeding season)
- Invertebrates: speed of development often not as crucial as in arid areas. Life‐cycle usually completed in a season.
- Larger animals, e.g. Mountain pygmy‐possum ‐ synchronised breeding season, fast growth etc.
Mountain pygmy possum breeding partern
‐ highly seasonal
‐ Entirely limited to alpine regions
‐ Thought extinct until 1966, now endangered
‐ 30 – 80g & lives 5 – 12 (?) years
‐ Habitat: alpine boulder fields and rock screes
‐ Mating occurs when snow melts and Bogong moths arrive
(store body fat)
‐“Tunnel of love” built at ski resort ‐ sexes occupy different
habitats that had been fragmented by a road
Bogong moth breeding partern
Small grey‐brown moth (wingspan approx 4cm), alpine seasonal migrant
• Larvae winter in pastures in Sth QLD, NSW & SE Vic, but food plants dry off over summer
• Intolerant of summer heat
• Adults migrate to alpine areas, shelter in caves & crevices >1500m during spring/summer up to
17,000 individuals/m2
• Aestivate when in alpine zone ‐ survive on fat stores
Tropical rainforest in Australia:
- 70-100% canopy cover,
- max. canopy height 40-50m
- Sea level to 1600m
- upland RF (cooler), fewer animal sp.
- lowland RF (below 1000m), more sp.
- Rainfall reliable, >1500 mm/year
- only 1-2% of total land area of Oz
- supports very high faunal diversity
Tropical rainforest diversity
Birds 128 species 16.5% of total australia
Reptiles 160 species 23% of total australia
Frogs 47 species 23 of total Australia
Mammals 89 species, 33 of total australia
Invert.s ????* ??*
number of invertebrate species unknown (over 75,000 sp.known only from Australia’s tropical rainforests)
Constraints for research in tropical
rainforest:
- remote
- often logistically difficult
- wet season flooding and isolation
- many sp. difficult to find & difficult to catch
Known diets of other Petaurid possums:
- Plant exudates (sap, gum, nectar) a major component of diet
- Smaller species supplement diet with invertebrates
Unusual morphological characters
of Striped Possums
- Klinorhynchy (rounded cranium)
- Large procumbent lower incisors
- Tongue & 4th finger elongated
-Suggestive of dietary specialisation diet of invertebrates
Prediction: that striped possums are insectivores & will therefore require much larger areas of habitat than other petaurid possums
Striped possum diet
- wood-boring beetle larvae and social insects very important in diet
- other invertebrates taken opportunistically
- plant exudates used occasionally
Why do tropical rainforests support
high animal diversity?
- habitat patchiness (potential speciation)
- high complexity
- high productivity
Habitat patchiness
- large area of habitat but varies at a local scale: potential barriers to movement which restrict/prevent populations of some species from mixing
-Habitat patchiness (local scale) can result in the isolation of sub-populations of some
specie - potential for speciation (e.g patch of eucalyptus forest)
-Larger scale, geographic barriers (e.g. valleys between mountains) can also result in the isolation of sub-populations
Habitat or geographic barriers impact variably on animal species depending on their
- mobility
- body size
- degree of habitat
specialization
- high complexity
High complexity: carnivorous birds exploit high complexity
Red Bellied Pitta specialises on rainforest snails
High productivity:
• Frugivorous (herbivorous) birds exploit high productivity & lots of fleshy fruit available in rainforest
• Tropical rainforest trees often fruit heavily and are used by many species
-Temporal separation in resource use reduces competition: birds feed during day, mammals feed at night
-Feathertail glider feeds on nectar at night; honeyeaters butterflies & friar birds feed during day
Faunal links with PNG & Asia
Approx. 50% of Australian tropical rainforest birds are shared with Papua New Guinea
Buff Breasted Paradise Kingfisher
- Over-winter in PNG
- Migrate Oct/Nov to breed in lowland rainforests of Cape York
- Form pairs, establish territories, nest intermite mounds
- Adults migrate back to PNG March-April, (juveniles later)
- Mobile species so water crossing not a barrier
Little Red Flying Fox:
Flying foxes highly mobile, capable of long distance movements.
Effectively one large population in Australia & PNG
Giant White-Tailed Rat
distributed in Australia & PNG, but no current
movement between populations
Fossil record for tree kangaroo distribution:
once widespread, distribution contracted with rainforest contraction as the continent dried out
Early vs. recent arrivals example
-F: Hylidae ‘Tree Frogs’ F: Myobatrachidae ‘Ground Frogs vs F: Ranidae ‘True Frogs’
-mammals: Australian native rodents originated in Asia (i.e. relatively recent arrivals), musky rat kangaroo a Gondwanan group
-
Endemic species
• unique to a particular geographic region or locality,
• assumed to have evolved there.
Large number of endemic species in Australian tropical rainforest, so should be given high conservation status if under threat
Endemic species example
-Lemuroid Ringtail possum
-Golden bower bird: occurs above 900m, feeds on fruit, males build a bower to attract females
-Boyd’s forest dragon: little knowledge of biology, occurs in very dense rainforest areas, distribution: high & low altitude
-Orange-thighed tree frog: little knowledge of
biology, recognised as a distinct species in 1986
Cape York graceful tree frog: described in 2016
-Musky rat kangaroo
Key issues for endemic species:
- limited distribution, often habitat specialists (loss of habitat or population = loss of that species world wide)
- often rare & difficult to study, often little knowledge of biology problematic for conservation
Key conservation issue: cause loss of biodiversity
- Habitat loss: extensive clearing of tropical rainforest is a direct threat to fauna
- Impact of increasing human population: increasing human popn s, development, and changed land management, along with continuing traditional hunting
- Poaching Wealthy animal collectors drive poaching of rare species for their private collections
- Disease
Human activity in rainforest
Australian tropical rainforest:
* 23% cleared
* 22% impacted by agriculture
* 35% used at some level for forestry production
So 80% impacted by some form of human activities, only 20% undisturbed = huge potential impact on fauna
• Disturbance creates ‘edges’
• Opens up forest to invasion by weeds and feral species
Loss of components of habitat:
Ulysses Butterfly - dependent on one plant
genus for oviposition: Genus: Melicope, caterpillars feed on it’s leaves
Role of animals in nutrient cycling
Cassowary
* Feeds on fruit and disperses seeds
* Large birds, thus can carry large seeds & a large volume of seeds
* Large home ranges (smaller at lower elevation)
* Populations declining in many areas
Musky rat kangaroo: important seed dispersers in rainforest via scatter-hoarding
Contribute to forest regeneration and ecosystem health
Amphibians
• First vertebrate group to exploit the terrestrial environment
• Limbs & lungs: terrestrial life
• Still dependent on moist environments
‐ adults have highly permeable skin
‐ eggs without shells, many spp. require water
for reproduction
• Ectothermic
Amphibia Worldwide
• Three orders: Anura ‐ frogs& toads Caudata ‐ newts & salamanders Gymnophiona ‐ caecilians (legless)
Anura – the only order native
to Australia
• 21 families worldwide • 5 families native to Australia (new classification 2014) Limnodynastidae Ground frogs Myobatrachidae Southern frogs Hylidae/Pelodryadidae Tree frogs Microhylidae Tiny tree frogs Ranidae “True” frogs
F: Limnodynastidae Ground frogs
40 spp. 8 genera Widespread distribution in Australia
• All 40 species in Australia
• Extensive adaptive radiation in Australia
• Wide range of ecological and developmental specialisations
• Variety of life history patterns
• Most are burrowing or terrestrial, none are arboreal (living inn tree)
Myobatrachidae Southern frogs (toadlets & froglets)
- All 88 species in Australia
- Extensive adaptive radiation
- Wide range of morphological, ecological and developmental specialisations
- Variety of life history patterns – from fully aquatic to terrestrial
- Adults: burrowing and terrestrial
Turtle frog
- Strictly terrestrial – no aquatic phase in life cycle
* Often found in termite mounds or in burrows
Hylidae
Tree frogs
• Worldwide, but mostly in Australia and S. America
• 73 species (3 genera) in Australia: Litoria, Cyclorana & Nyctimystes
• Widespread & successful in Australia
• Typical water‐dependent reproduction
• Adaptations to extreme environments
– arid zones
– rainforests
Microhylidae Tiny tree frogs
• 18 species (2 genera): Sphenophryne & Cophixalus • Tropical northern Australia • Small, from 1‐3 cm: hard to find unless calling • Direct development
The nursery frogs
- Lay clutch in moist soil under rocks, leaf litter
- Eggs coated with anti‐fungal agent
- Male guards eggs
- Tadpole develops inside egg, froglet hatches out
- Restricted distributions, some species very rare
Ranidae “True” frogs
• Most successful family worldwide
• Only one species/genus in Australia:
Papurana daemeli (wood or water frog)
Cane toad Rhinella (Bufo) marinus
• Family Bufonidae
• Introduced to Australia in 1935 to ‘control’ cane beetles
• Up to 25,000 eggs/spawn
• Range expansion ~ 50 km/yr
– arrived in Kakadu NP 2001
• Poisonous glands: major problem for native wildlife
Extremes of water‐independence
& parental care in frogs
Myobatrachid frogs:
• Assa darlingtoni “marupsial frog”; males carry
developing tadpoles in brood pouches. Very small
distribution: NSW‐QLD border
• Rheobatrachus spp.; gastric‐brooding frogs from
Queensland rainforests
Where have all the frogs gone?
- Sudden, dramatic decline in frog numbers in many countries – commenced late 1970s
- Frog declines noted throughout Australia, mostly QLD, NSW, VIC
- Australia: 33 species listed as threatened or presumed extinct (EPBC Act)
Declining frog populations ‐
possible causes:
- Habitat loss & fragmentation
- Disease
- Climate change
- Pollution
- Introduced predators
Reptiles
First really successful colonisers of earth’s terrestrial environments:
• amniotic egg: embryo in fluid-filled sac, with a shell, thus more resistant to drying compared with amphibians
• internal fertilisation
• scales: prevent water loss (not permeable)
Reptile characters cont
• Excrete urea (thick paste) reduces water loss
• Faeces very dry (water conservation)
• Ectotherms: constrains activity in cooler climates, but also means
energy requirements relatively low
(most reptiles can go for considerable periods without feeding)
Characters make reptiles well suited to exploiting terrestrial and in
particular arid environments
Reptiles around the world
• Order Crocodilia: crocodiles & alligators
• Order Testudines (Chelonii = past name):
turtles & tortoises
• Order Squamata: snakes & lizards
• Order Rhyncocephalia: tuatara (NZ only)
Reptiles are not monophyletic
•squamata: lizards + snakes
• crocodiles are closest to birds and dinosaurs
(Archosauria)
•turtles branched early from the stem leading to
archosaurs and lepidosaurs
Sauropsida: ancestor of all reptiles and birds
Australia – a land of reptiles
Approx. 984 described species in Australia (North America 280 spp.) - Desert and tropical “hotspots” - 90% are endemic! Crocodiles 1 Family 1 Genus 2 Species Turtles 4 Families 15 Genera 29 Species (snakes and lizards)
12 Families
146 Genera
953 Species
Squamates
Crocodiles
• Heavily armored body, long jaws, streamlined body, powerful tail • Aquatic predators • Ancient – 240 million years old • All lay eggs, exhibit maternal care • Tropical distribution (good temperature for ectotherm activity)
Australian Crocodiles
Crocodylus porosus saltwater crocodile “saltie” Crocodylus johnstoni freshwater crocodile (endemic to Australia) “freshie
Turtles Order Testudines (Chelonii):
4 families in Australia in freshwater (not tortoises) Family Chelidae – side-necked turtles (Gondwanan) – freshwater sp. 8 Genera 22 Species Family Carettochelydidae – pitted-shelled (pig nosed) turtle – freshwater sp. 1 genus 1 species
Australian Turtles cont. - marine sp
Family Cheloniidae – marine turtles 5 genera, 5 species • Wide global distributions • Females return to birth site to lay their eggs • Extraordinary powers of navigation • Most species are of conservation concern Family Dermochelyidae - marine 1 genus, 1 speciesl • Worlds most widespread reptile • Worlds largest turtle – up to 900kg • Dietary specialist - feeds entirely on jellyfish • Currently endangered in Australia
Australian Lizards
7 families
most with legs,
some without
F: Agamidae – “dragons”
- Australia: 16 genera, 80 species (320 worldwide)
- Australian group, largely endemic
- Geographically widespread in Oz
- Typically: strong legs, fast moving, sun-loving lizards
- All oviparous – lay eggs in burrows
- Visual displays during courtship including head bobbing, arm waving
Geckos
Australian geckos, recently divided into 3 families:
Geckkonidae, Diplodactylidae & Carphodactylidae
• 25 genera, 148 species (800 worldwide)
• Most diverse in arid & tropical areas, none in TAS
• All Australian geckos are nocturnal
• All oviparous: 1 - 2 eggs/clutch
• Some parthenogenic
• Highly vocal
• Tail autonomy
Some geckos have “sticky feet”
F: Pygopodidae –
legless lizards
• 7 genera 43 species in Australia • Endemic to Australia and PNG, none in TAS • Closest relatives to geckos (some older Australian gecko groups now classified with pygopodids) • Tail autotomy • 1 – 2 eggs/clutch • Vocal • No forelimbs • Hind-limbs: reduced to small flaps
F: Scincidae
skinks
- Skinks, blue-tongues and stumpy-tailed lizards
- 41 genera 439 species (> 1000 worldwide)
- Most diverse lizard family worldwide
- Largest group in Australia – occur everywhere
- Highly variable in morphology, ecology etc.
- Both oviparity (eggs) and viviparity (live young)
- Some have reduced limbs
F: Varanidae –
monitors/goannas
- 1 genus (Varanus) 29 species (approx. 38 worldwide, includes Komodo dragon)
- Widespread worldwide, but Australia stronghold for family
- All oviparous – up to 35 eggs/clutch
- Perhaps the closest relatives to snakes (both have forked tongue)
Australian Snakes
5 families,
Approx. 213 sp.
no legs
F: Typhlopidae – blind snakes
• 1 genus 43 species (approx. 150 worldwide) • Light sensitive eye spots • Insectivorous • Rarely seen – small, nocturnal & burrowing • Oviparous? • Little known family
F: Pythonidae - pythons
• 6 genera, 15 species (25 worldwide)
• Most diverse in northern Australia
• Large, muscular snakes (up to 7 m)
• Mostly nocturnal, heat-sensitive pits around mouth for
detection of endothermic vertebrate prey
• Kill prey by constriction: asphyxiation, may also cause
huge increase in blood pressure so heart can’t pump
• Oviparous
F: Acrochordidae - file
snakes
• 1 genus, 3 spp. • Wholly aquatic: - 1 marine, northern Aust. - 2 freshwater, tropical lagoons northern Aust. • Fish-eaters (rough skin) • Non-venomous • Viviparous • Quite recent arrivals in Oz
F: Colubridae
“tree snakes”
- Low diversity in Oz: 5 genera, 7 species (> 1600 worldwide)
- Only northern and eastern coastal Australia, mostly arboreal and semi-aquatic
- Very recent arrival in Australia - only one endemic species & not present in fossil record
- Display both oviparity and viviparity
F: Elapidae – venomous land
snakes & now includes the sea
snakes
- 56 genera 141 species
- Front-fanged
- Radiated into all Australian habitats
- Includes all the venomous terrestrial species + many non-dangerous species
- Australia has 10 most venomous snakes in the world
- Both oviparity and viviparity
Sea snakes (both groups of sea snakes now classified with Australian elapids)
SF: Laticaudidae (sea kraits) • 1 genus, 2 species • Come ashore to lay eggs SF: Hydrophiinae (sea snakes) • 11 genera, 34 species • viviparous - wholly aquatic, thus bear live young
Reptile reproduction:
1. oviparity
- Ancestral condition was oviparity
- Many modern species remain egg-layers
- Most lay eggs in burrow, some goannas lay in termite mounds
Reptile reproduction:
2. Viviparity
• Some snakes and lizards have evolved viviparity • Viviparity has evolved independently > 100 times in reptiles worldwide • Most common in southern, colder areas
Reptile reproduction cont.:
3. sex determination
- sex determination - in some groups is temperaturedependent
In marine (Cheloniidae) & pitted-shelled turtles
(Carettochelyidae)
• < 30oC all males
• 30-32oC mixed males & females
• > 32oC all females
(above is for some Australian turtles – pattern
varies across groups in other parts of world)
In contrast: Family Chelidae: exhibit genetic sex
determination (like mammals & birds)
Climate change and sex ratios
• Increasing temp favours one sex
• (males in crocs, females in turtles)
• For most incubation > 34 deg increases malformation and mortality
• Rising sea level will increase nest flooding
• Green sea turtles in QLD, pivotal incubation temp is 29.3 deg
• Chart shows sand temp records above
(favours females) and below (favours
males) this pivotal temp
• Sex ratios of nests in northern Great Barrier Reef are > 99% female
Evolutionary history of bird
Shared ancestor between birds & dinosaurs: Dromaeosurid theropods - e.g. Velociraptor
Archaeopteryx – oldest known fossil bird 147MY (Jurassic)
• Theropod dinosaur with flight feathers
• “Missing link” between dinosaurs and birds
have reptilian features (long tail, teeth, claw wing) and bird features (feather)
Why evolve Flight
• Air - unexploited habitat • Abundance of prey (flying insects) • Escape from terrestrial predators • Allows wide and fast travel • Migration – access to year-round favourable climate and resources (bats hadn’t evolved yet!)
What drove the evolution of flight?
Three theories
Ground Up (most likely)
• Wings evolved from arms used to capture small prey
• Wings evolved because bipedal animals were leaping into the air; large wings (forelimbs) assisted leaping
Trees Down
• Wings evolved from gliding ancestors that began to flap their gliding structures in order to produce thrust (individuals with better wings “selected” for??)
Sexual selection
• Wings were used as sexual display structures: bigger wings
were preferred by potential mates.
Australian bird fossils
• birds make poor fossils - small delicate bones
• 110 MYA fossil feathers from Koonwarra, Vic
• 30 MYA penguin fossils & dromornithid tracks
• 20 MYA extensive fossils of wetland
birds in Central Australia
Dromornis stirtoni
Central Australia - 15 mya
• Flightless, weight 500+ kg, 3m tall
• Related to geese (also flock)
Genyornis:
present in Australia until approx 50,000
years ago. Rapid extinction due to climate change??
Characters that define birds
- Feathers
- Wings (but not all can fly, some are secondarily terrestrial or amphibious)
- Very light, very strong skeleton, bones hollow
- Beak (no teeth)
- Lay hard-shelled eggs (oviparous)
- Endothermic
Modern birds:
Class: Aves (Paleognathae & Neognathae) - Order Passeriformies (passerines) = “perching birds”/song birds. Contains approx ½ worlds sp. Most diverse & widespread group worldwide & occurs in Australia - non-passerines 25 - other Orders of birds (18 in Australia)
Diversity: worldwide (Class Aves)
- Approximately 10,000 living species (more species than any other vertebrate group except fishes)
- From 1.8g to 160 kg
- Occur in all habitats
- Numerous highly social groups: very interesting behaviour
Bird Diversity in Australia (including offshore
islands):
about 898 species only 45% endemic
Convergent evolution
• most Australian bird spp. are corvids, descended from
ancestors of crows/ravens
-DNA studies allow origin and evolution to be unravelled
- they are not closely related to NH bird but share similar apperance
Five broad categories of Australian birds
- Long-established non-passerines of Gondwanan
origin - Australasian passerines (perching/song birds)
descended from Corvid family (crows/ravens) - Recent passerine colonists from
Eurasia - Introduced species
- Worldwide groups
- Long-established non-passerines of Gondwanan origin:
These groups not closely related, but present for a long time in Australia
a) ratites
b) parrots
c) penguins
ratites
– emu & cassowary : flightless, bulky
-Distribute in SH
Kiwis – 5 species, smallest only 1.2 kg, only present in NZ
“parrots
• 332 spp, mostly Southern Hemisphere - 88 Australasian endemics - 54 spp. in Australia • Family Cacatuinidae - Cockatoos (endemic) • Family Psittacidae - Parrots
“Parrot” characteristics
- Very strong curved beak - feed on cones, seeds, fruit, nectar
- Strong legs & claws - can manipulate food
- Most are brightly coloured & often lack sexual dimorphism
- Occur in all habitat types
- Most nest in tree hollows
- Many are long-lived
Cockatoos
- endemic to Australia and PNG
* have a crest
Parrots - diversity of ecology and
distribution:
- many species form flocks
- many species pair – monogamy
- habitats: rainforest, woodlands mallee, arid zone, etc.
- some sp. make long-range movements to escape drought
- Some species have very broad distributions, others are very restricted
Penguins
-17 species around the world, 1 in australia
Worldwide bird groups
Strong powers of dispersal
• Raptors (birds of prey)
* Diurnal - eagles, kites, falcons etc.
(but no vultures or secretary birds in Oz) 22sp
* Nocturnal - owls, nightjars & frogmouths 16sp
• Seabirds and shorebirds
Diversity in bird breeding biology:
1. Mating systems
Usually strong association between mating system and level of parental care •monogamy •polygyny •polyandry •promiscuity
Monogamy
- one male mates with one female
- pair bond lasts for between one season and a lifetime (varies in different sp.)
- pair mate, incubate and raise chicks together
- most widespread pattern in birds
Monogamy in albatrosses
- single chick takes up to 280 days to reach independence
- parents take turns to undertake long foraging trips
- high demands of chick rearing favours evolution of monogamy
‘Monogamy’ in black swans
- males and females pair for life (social pairs)
* about 15% (1 in 6) cygnets are ‘illegitimate’
Philandering in “monogamous”
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
Polygyny
• 1 male mates with several females • Sexual dimorphism common • Males often exhibit courtship and have elaborate colouration cmpd to females e.g. riflebirds • or males build structures \+ exhibit courtship e.g. bower birds i.e. males compete for females • Generally no male contribution to care
Satin Bowerbird
- 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”
- Female builds nest & raises young alone - polygyny
Polyandry
- 1 female mates with several males
- separate clutches for each male
- may be ‘successive’ or ‘simultaneous’
- male raises offspring
Southern cassowary polyandry
- female lays for up to 3 males
- male incubates 2 months
- extended male care: 9 months
Forms of parental care in birds:
- bi-parental
- paternal or maternal
- mound-builders (care during incubation)
- cooperative breeders (the whole family)
- no care
Bi-parental care: little penguins
- Chicks are raised in underground burrow
* Male and female alternate shifts during incubation and feeding
Paternal care: emus
- successive polyandry
- male builds nest (2m diam.)
- female lays 5-15 eggs
- male incubates clutch for 55 continuous days
- male continues to care for young for up to 6 months
Mound builders
- Family Megapodiidae: SE Asiacentered distribution
* 3 species in Australia:
Malleefowl
- eggs laid inside a mound built by parents
- rotting process generates heat: incubates eggs
- male maintains mound @33oC
- chicks independent at hatching (no further care)
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 helpers stay?
• 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
Cooperative extremes - choughs
and apostlebirds
• live in groups of 2-20 individuals - highly social
• difficult foraging niche (subsurface invertebrates)
• slow transition to independence for young
• acute dependence on helpers:
- nesting pairs and trios always fail
- groups may try to kidnap helpers!
No parental care -
brood parasites
• Inter-specific brood parasitism
– female drops eggs into nests of a different “host” sp. e.g. cuckoos
• Intra-specific brood parasitism
– female lays some eggs into nests of same sp. e.g. swallows, coots etc. (but females will also have own nest)
Australian cuckoos
- cuckoo adds an egg to the clutch of the ‘host’
- cuckoo chick develops more quickly and hatches earlier than host chicks
- cuckoo chick ejects the host eggs & is fed by host
Canny cuckoos and wily wrens: an
evolutionary ‘war’
- 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
Bird song - two main functions
• territory defence • mate attraction (mostly males sing) Australian themes: • female song • duets • vocal mimicry
Duetting in eastern whipbirds
- 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
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
Vocal mimicry: male superb lyrebird
80% of songs mimic ‘natural’ and mechanical sounds
Conservation: threatening processes for bird
• Loss of tree hollows (breeding sites) • Clearance for agriculture • Predation - ferals -alternate fire regime • Grazing • Direct exploitation - hunting - bird trade
Illegal pet trade
- Burgeoning parrot trade
- High return/low risk for traders
- Also trade in eggs
Conservation programs for rare sp.:
orange-bellied parrot
- Critically endangered
- ~ 50 individuals left in wild
- Migratory species
Orange-bellied parrot - causes of decline
• 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 left in wild????
• Large-scale human “reclamation” (damage) of saltmarsh habitat (= winter refuge &
feeding grounds)
• Mineral exploration, uncontrolled fires in breeding area
• Low breeding success (1.7 young/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??
• Recent finding: sugar gliders (introduced to Tas), may prey on parrots
OPB: Conservation initiatives
- 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 programes and re-introductions to wild – these have failed to improve status of wild population
- Banding, monitoring and census of winter and breeding populations ongoing
