Adaptations of the quokka (Setonix brachyurus)

Adaptations to heat

When temperatures are above 32℃

Move to shady trees where dry air aids in evaporative cooling

Temperature dependent habitat

Swamp bushes

When temperatures are below 32℃

DIET

This diverse range of food source allows quokkas to fill and undergrowth niche within the ecosystem

ADAPTATIONS OF THE QUOKKA (SETONIX BRACHYURUS)

Physiology

When food is vast, quokkas digest over 1.5-2.5 days

When food is limited, digestion takes longer, up to 6 days.This also represents an increase in nutrient absorption (Calaby, 1958).

Bipedal adaptation; small forelimbs used at low speeds, large hindlimbs for hopping forward with elongated feet connected by fibrous muscle.

Rottnest island population 8000-12000 bald island 200-600. No established mainland populations

We estimate that the 5000 quokkas on Rottnest I. consume at least 100 000 kg of plant matter (dry mass) per year

If all this water was from food, and feeding rate was 55 g (dry matter) per day (see above),

then the water content of the diet would be 58% [(74.4 mL d-')/(74.4 mL d-' + 55 g dry food d-')I.

Importance of quokka shelter, hide from predation of owls and foxes, introduced from european invasion.

Quokkas show a preference for young swamplands that have been recently burnt. This is likely due to increased nitrogen levels. Further, young swamplands have have foilage within reach and dense bush for protection from predators.

Eyes don’t fully develop until 87 days. during development the composition of the milk changes to meet the nutritional needs of the developing young.

When quokkas are cold, they shiver in order to heat up, much like humans. This action is controlled by the peripheral temperature receptors in the skin.

Habitat

When it is hot, quokkas will seek shade in shrubs, as they have a lower radiant heat load (Hayward, de Tores & Banks, 2005).

Survival mechanism: will expel young from pouch when pursued by foxes or cats which has a negative impact on population growth over long periods of time

Sexually dimorphic- males larger than females . No migration between the two populations on Rottnest island and Bald island. Largest genetic diversity is observed in the in the mainland population. There is evidence of bottle-necking within these populations

Weighing in at 2.5-5 kg and maturing to 40-50cm in height the quokka is a short macropod

Polyoestrous cycling every 28 days breeding period from january to august. Able to breed from 18 months of age Give birth to a joey within minutes moves to the pouch within minutes of birth

They have an ideal internal body temperature of 37-38℃

Quokkas are browsing herbivores, eating many types of grasses and vegetation. These include:

-heath and shrubland on the mainland coast and offshore islands

-Swamp Peppermint (Taxandria linearifolia) dominated swamps in Jarrah (Eucalyptus marginata) forest

-swampy shrublands

-swordgrass-dominated understorey

-regrowth areas of the Karri (E. diversicolor) forest

-Bullich (Eucalyptus megacarpa) swamp forest

-Paperbark (Melaleuca spp.) swamp

although quokkas eat large amounts of grasses and vegetation, Guichenotia ledifolia, a small species of shrub has been identified as a favourite food source for quokkas

Heating

Quokkas use evaporative cooling by licking their paws, tails and bellies

Cooling

Quokkas move from shrubs (high heat retention) to trees (lower heat retention) in order to stay cool