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
