Quokka Setonix Brachyurus Research Articles

The Effect of Visitor Number on the Behavior of Zoo-Housed Macropods

ABSTRACT Free-range exhibits are used by zoos to allow visitors to experience or interact with animals in a semi-natural setting; close interactions with animals have been shown to increase empathy and contribute to conservation outcomes, and as such zoos are increasingly implementing free-range style exhibits to facilitate this goal. We aimed to investigate whether this close proximity to zoo visitors impacted upon four species of macropod (red kangaroo Macropus rufus, red-necked wallaby Macropus rufogriseus, swamp wallaby Wallabia bicolor, and quokka Setonix brachyurus) in a free-range exhibit in an Australian zoo. Specifically, we used instantaneous scan sampling to assess animal behavior and examined whether visitor number affected the proportion of individuals that exhibited four target behaviors; visitor-directed vigilance, retreat, resting, and foraging behavior. We found that the proportion of individuals exhibiting visitor-directed vigilance significantly increased as pedestrian visitor number increased for three of the four species, and the proportion of individuals that were resting was significantly negatively related to visitor number for both wallaby species. The proportion of individuals of each species foraging or retreating was unrelated to visitor number. These data suggest that a visitor effect exists in a walk-through exhibit of macropods, and once visitor numbers go beyond a threshold, the behavior of more animals is impacted, likely compromising welfare. Interestingly, quokka do not appear to be affected by zoo visitors; which may be due to visitor pressure being perceived differently due to evolutionary differences, or that housing and husbandry ameliorate the visitor effect for this species but not others. Like many studies before, taking a species-specific approach to understanding zoo visitor–animal interactions has determined how the visitor effect likely impacts macropods differently.

Are tourism and conservation compatible for ‘island tame’ species?

AbstractIslands play an important conservation role due to high rates of speciation as well as providing a predator‐free refuge environment for species that are vulnerable to terrestrial predation on the mainland. Many animals show marked ‘island tameness’ on predator‐free islands, reducing costly escape responses in the absence of predation threat. Island tameness also translates to altered responses toward humans, making many island species attractive for wildlife tourism. We explored temporal and spatial differences in behavioral responses in the Rottnest Island quokka Setonix brachyurus. This marsupial is an excellent species to test for the effects of ecotourism, as well as of being conservation significance (IUCN‐listed as vulnerable). Comparing escape responses for n = 339 individuals in high tourism and low tourism seasons, quokkas at tourism sites allowed a person to approach closer before moving away compared with non‐tourisms sites, and two‐thirds of individuals around tourism sites allowed a person to approach within 1 m (compared with 14% of individuals at non‐tourism sites). For n = 67 ad hoc interactions with tourists, quokkas would only move away from an interaction with a tourist when the tourist group was noisy or there was an attempt to touch the animal. Time budgets (n = 379 individuals) showed that quokkas spent more time in group behavior and locomotion, but less in vigilance and feeding for tourism sites compared with non‐tourism sites. Understanding the impact of ecotourism on animal behavior will help to frame conservation management actions to ensure persistence of threatened wildlife species. We propose two models describing animal responses toward ecotourism: spatial separation according to animal temperament or temporal adjustment due to learned habituation. These models are not mutually exclusive and we suggest that both spatial separation and habitation are likely evident for Rottnest quokkas. We discuss the implications of these results for protection of animals on the island as well as for species conservation.

Home range and movements of the quokka Setonix brachyurus (Macropodidae: Marsupialia), and its impact on the viability of the metapopulation on the Australian mainland

AbstractThe home range and movements of the quokka Setonix brachyurus, a medium‐sized macropodid marsupial, were investigated using radio telemetry. Fifty‐eight quokkas from five remnant mainland populations in the northern jarrah (Eucalyptus marginata) forest of Western Australia were radio‐collared and monitored for up to 2 years between 1998 and 2000. Mean (±se) home‐range sizes were 6.39±0.77 ha and core ranges averaged 1.21±0.12 ha. Male core home ranges were larger than those of females although not when corrected for body mass. Nocturnal ranges were larger than diurnal owing to nocturnal departures from the swamp. Ranges shifted to the edge of swamps in winter, as the swamps became inundated following rain, and toward the centre in autumn as the swamps dried. Quokka populations are thought to exist below carrying capacity at all sites and this probably caused the lack of dispersal observed in this study. We hypothesize that predation is suppressing population booms which would otherwise drive dispersal and thereby maintain metapopulation dynamics. Without dispersal to rescue unpopulated patches, we conclude that the original quokka metapopulation has collapsed and ameliatory measures are required.

Development of the lymphoid tissues of the tammar wallaby Macropus eugenii.

A study has been made of the development of four lymphoid tissues from birth to maturity in the tammar wallaby Macropus eugenii--the cervical and thoracic thymus, lymph nodes and gut-associated lymphoid tissue (GALT). The development of these tissues in the tammar wallaby is similar to that in two other marsupials, the quokka Setonix brachyurus and the Virginian opossum Didelphis virginiana. Lymphocytes were first detected in the cervical thymus of the tammar at Day 2 post partum and in the thoracic thymus at Day 6. They were subsequently detected in lymph nodes at Day 4 and in the spleen by Day 12 but were not apparent in the GALT until around Day 90 post partum. By Day 21, the cervical thymus had developed distinct areas of cortex and medulla and Hassall's corpuscles were apparent. The maturation of other tissues followed with Hassall's corpuscles in the thoracic thymus by Day 30 and nodules and germinal centres in the lymph nodes by Day 90. Measurement of immunoglobulin G concentrations in the serum of young animals indicated a rise in titre around Day 90 post partum, correlating with the apparent maturation of the lymphoid tissues.

Resolution of portions of the kangaroo phylogeny (Marsupialia: Macropodidae) using DNA hybridization

We generated a DNA hybridization matrix comparing eleven ‘true’ kangaroos (Macropodinae) and two outgroup marsupials, the rufous rat-kangaroo Aepyprymnas rufescens (Potoroinae) and the brush-tailed phalanger Trichosurus vulpecula (Phalangeridae). A small matrix included additional species of the genus Macropus (large kangaroos and wallabies). The results indicate that the New Guinean forest wallaby Dorcopsulus vanheurni , and the quokka Setonix brachyurus, represent successively closer sister-groups of other macropodines. The remaining taxa examined form two clades: the tree kangaroo Dendrolagus matschiei with the pademelons Thylogale and rock wallabies Petrogale , and Macropus including the swamp wallaby Wallabia bicolor . The smaller matrix of five Macropus species and Wallabia (with Dorcopsulus as an outgroup) pairs the red-necked wallaby M. rufogriseus and Parry's wallaby M. parryi , with the eastern grey kangaroo M. giganteus as their nearest relative; and associates the red kangaroo M. rufus and wallaroo M. robustus , with Wallabia as their sister-taxon. In the larger study, we found that inclusion of both outgroups provided little resolution among the macropodines, judging by jackknife and bootstrap tests. When Aepyprymnus was deleted, the Dendrolagus-Thylogale-Petrogale association obtained; with Trichosurus eliminated instead, the Wallabia-Macropus group was recovered. Only analysis of the eleven ingroup taxa by themselves gave a topology which supported both major clades. Our findings suggest that, at least for DNA hybridization studies, when ingroup taxa are separated by very short internodes experimental error in outgroup-to-ingroup distances may seriously compromise determination of ingroup affinities as well as the position of the root. We recommend that in such cases separate analyses with the outgroups sequentially eliminated and rigorous validation of the topology at each step should be conducted.

Development of the Visual Cortex in a Wallaby – Phylogenetic Implications

The visual cortex of one of the smallest macropod marsupials, a wallaby, the quokka Setonix brachyurus, was examined at maturity and during development from postnatal day 1 to 150 in Nissl-stained or Golgi-stained sections. Injections of horseradish peroxidase into the primary visual centres in adults identified cortical neurons projecting to these regions. The pattern of cell generation was determined by tritiated thymidine/autoradiography. The adult visual cortex was composed of the usual six layers of cells with dendritic morphologies similar to those seen in eutherian (placental) mammals. The margin of Layer 6 overlapped slightly with the white matter, and pyramidal cells projecting to subcortical regions were located at all depths of Layer 6. Cortical development was similar to that of eutherian mammals, with the formation of transient cellular layers below the developing cortical plate. Autoradiographic studies confirmed that the cortical plate was composed of two layers: a compact zone of densely packed cells located pial to a striated layer containing more loosely packed cells. Postnatal cell generation of Layers 6-2 took place from postnatal day 3 to day 85, with Layer 4 neurons, the main target of incoming visual axons, being generated around postnatal day 40. Cells located at maturity in the white matter, mostly of glial morphology, were generated from postnatal day 40. A subplate zone containing early differentiating cells was not evident, and postnatal 3H-thymidine labelling did not identify a population of early generated neurons below the cortical plate. In the tammar wallaby Macropus eugenii, the majority of target neurons for incoming geniculate axons are generated about 20 days after the first axons enter directly into the cortical plate without a waiting period in a subplate. Geniculate axons in the wallabies have a relatively longer 'wait' for their target neurons than do those in cats or monkeys. Therefore, if geniculate axons in marsupials make temporary synapses, while they wait for their target neurons to be generated, their temporary connections must, unlike those in cats or monkeys, be with cells already in the cortical plate.

Metabolic effects of cortisol, ACTH, adrenalin and insulin in the marsupial sugar glider, Petaurus breviceps

The effects of cortisol, ACTH, adrenalin and insulin on indices of carbohydrate, fat and protein metabolism were investigated in the conscious marsupial sugar glider Petaurus breviceps. Short-term i.v. infusion of cortisol at dose rates of 0.02, 0.2 and 1.0 mg/kg per h caused the plasma glucose concentration to rise sharply from the normal range of 3.3-4.4 to 8.1-8.7 mmol/l at the end of the infusion period without significant alteration in plasma free fatty acid (FFA), amino acid or urea concentrations. Infusions of ACTH at dose rates of 0.02, 0.06 and 0.45 IU/kg per h caused a similar rise in plasma glucose concentration; however, this was now accompanied by an elevation in plasma FFA concentration, but again without significant changes in either plasma amino acid or urea concentrations. Infusion of adrenalin at 10 micrograms/kg per h caused an increase in the plasma concentrations of both glucose and FFA. Intravenous injections of 0.15 IU insulin/kg caused a rapid and marked decrease in the plasma glucose concentration within 30 min and an increase in the plasma free cortisol concentration. Associated with this change was a marked rise in the plasma concentration of both FFA and free cortisol. The rise in free cortisol was, however, significantly reduced by infusion of glucose. Pretreatment with five daily i.m. injections of 1 mg cortisol acetate/kg, which produced an increase in plasma free cortisol concentration to near the maximum of the physiological range, caused a marked reduction in insulin sensitivity. Cortisol pretreatment caused an increase in the plasma FFA and amino acid concentrations. Petaurus breviceps is highly sensitive to the metabolic effects of glucocorticoids and is similar in this respect to the brush-tailed possum Trichosurus vulpecula. The interactive effects between insulin and glucocorticoids on carbohydrate, fat and protein metabolism in Petaurus breviceps are similar to those shown by Trichosurus vulpecula and some eutherian mammals but contrast with the pattern described for two macropodid marsupials, the red kangaroo Macropus rufus and the quokka Setonix brachyurus.

Copper-levels in the Milk of a Marsupial

IT has been shown that there is a seasonal anaemia, during the summer months, in a wild population of the quokka Setonix brachyurus Quoy and Gaimard, on Rottnest Island, Western Australia1,2. During an investigation of the possibility that copper deficiency was involved in the seasonal anaemia, it was observed that, in the spring (October) of 1958, female quokkas had lower haemoglobin-levels than did males, in two study areas (West End and Lake Bagdad) on the island. At the same time, female quokkas in the Lake Bagdad area had significantly lower copper-levels in their blood than did males in the same locality. At other times of the year, there were no differences between the sexes in haemoglobin- or copper-levels in the blood2. It was thought that the sex difference in copper-levels in the blood during the spring could be attributed to the fact that, at this season, the females are suckling large pouch young. In November, the young leave the pouch permanently, and feed mainly on solid food.