Ventilatory accommodation of oxygen demand and respiratory water loss in kangaroos from mesic and arid environments, the eastern grey kangaroo (Macropus giganteus) and the red kangaroo (Macropus rufus)

We studied ventilation in kangaroos from mesic and arid environments, the eastern grey kangaroo (Macropus giganteus) and the red kangaroo (Macropus rufus), respectively, within the range of ambient temperatures (T(a)) from -5 degrees to 45 degrees C. At thermoneutral temperatures (Ta=25 degrees C), there were no differences between the species in respiratory frequency, tidal volume, total ventilation, or oxygen extraction. The ventilatory patterns of the kangaroos were markedly different from those predicted from the allometric equation derived for placentals. The kangaroos had low respiratory frequencies and higher tidal volumes, even when adjustment was made for their lower basal metabolism. At Ta>25 degrees C, ventilation was increased in the kangaroos to facilitate respiratory water loss, with percent oxygen extraction being markedly lowered. Ventilation was via the nares; the mouth was closed. Differences in ventilation between the two species occurred at higher temperatures, and at 45 degrees C were associated with differences in respiratory evaporative heat loss, with that of M. giganteus being higher. Panting in kangaroos occurred as a graded increase in respiratory frequency, during which tidal volume was lowered. When panting, the desert red kangaroo had larger tidal volumes and lower respiratory frequencies at equivalent T(a) than the eastern grey kangaroo, which generally inhabits mesic forests. The inference made from this pattern is that the red kangaroo has the potential to increase respiratory evaporative heat loss to a greater level.     

Structure and function of the eastern grey kangaroo (Macropus giganteus) foot thump

Most species of the family Macropodidae (kangaroos and wallabies) make a distinctive foot thump by striking the ground with their hind feet when they detect potential danger. I used the eastern grey kangaroo Macropus giganteus as a model to examine (1) the acoustic characteristics and structure of the thump, (2) the social context in which free-ranging kangaroos thumped when approached by a human observer on foot and (3) the intended recipient of the signal. Thumps were about two-thirds of a second in length, generally composed of two noisy pulses, and had the majority of the signal energy below 7 kHz. Only adult kangaroos, of both sexes, were observed to thump. A higher proportion of solitary kangaroos thumped than grouped kangaroos, and a higher proportion of kangaroos thumped when visibility was poor, either because of habitat type or low light levels. Given the context in which thumps were given, the foot thump appears to be a signal to a potential predator with three possible functions: to startle, signal detection or deter pursuit.     

Prevalence of Salmonella in fecal samples of western grey kangaroos (Macropus fuliginosus)

This is the first extensive study of the prevalence of naturally acquired Salmonella infection in wild-caught kangaroos in Australia. Given the close association between kangaroos, livestock, and humans and the growing popularity of kangaroo meat, it is important to identify epidemiologic factors associated with infection in these marsupials in order to minimize the risk of Salmonella transmission. The overall prevalence of fecal Salmonella in 645 western grey kangaroos (Macropus fuliginosus) sampled across 10 locations in Western Australia was 3.6% (95% CI: 2.3-5.3). Seven Salmonella serovars were identified including Salmonella enterica serovar Muenchen, Kiambu, Rubislaw, Lindern, Champaign, Saintpaul and II 42:g,t:-. Prevalence was significantly associated with rainfall (P<0.05) and was highest in the April-June quarter (P<0.05). There was no association between age or sex and the prevalence of Salmonella in fecal samples. Our results suggest that, while kangaroos are infected with Salmonella in their natural habitat, infection is less common than in hand-reared joeys, pet kangaroos, and macropods raised in captivity. Care should be taken to maintain hygiene during the evisceration, processing, and handling of kangaroos and to adequately cook kangaroo meat prior to consumption to reduce the risk of salmonellosis.     

Erythrocyte osmotic fragility of red (Macropus rufus ) and grey (Macropus fuliginosus and Macropus giganteus ) kangaroos and free-ranging sheep of the arid regions of Australia

The mean corpuscular fragility (MCF) of erythrocytes may reflect phylogenetic characteristics as well as an animal's ability to respond to the osmotic challenges associated with cyclic dehydration and rehydration. This type of ecophysiological stress is commonly encountered by animals living in arid regions and low MCF may contribute to their ability to survive and thrive in these xeric habitats. The eastern grey kangaroo has only in recent times extended its range into the arid zone, and is considered a more mesic inhabitant than the red kangaroo. We therefore compared the ability of eastern grey kangaroos and red kangaroos to handle prolonged periods of water restriction, as well as the MCF of the erythrocytes of free-ranging red, eastern grey and western grey kangaroos found at the Fowlers Gap field station. In addition, the MCF of free-ranging sheep inhabiting the same pastures were used as an experimental control; they are phylogenetically unrelated yet are subjected to the same acclimatisation stresses. While red kangaroos exhibited greater tolerance of dehydration compared to eastern grey kangaroos, the MCF of all three kangaroo species was similar and more resilient to osmotic stresses (MCF, 130 mosmol/kg) than erythrocytes of sheep (MCF, 220 mosmol/kg). The MCF did not change with water restriction, however, the erythrocytes of long-term captive populations fed a comparatively better quality diet were more resistant to osmotic shock than the free-ranging animals. Phylogenetic commonality rather than ecophysiological responses to life in the arid zone appeared to influence MCF. The MCF values of sheep corresponded to that of other ovines; similarly the MCF of kangaroos concurred regardless of their preferred habitats, ecological history and differential success in the arid zone. Accepted: 29 August 2000     

Climatological correlates for body size of five species of Australian mammals

Size variation of body and skull of five species of Australian mammals (echidna, Tachyglossus aculeatus ; brush-tail possum, Trichosurus vulpecula ; eastern grey kangaroo, Macropus giganteus ; western grey kangaroo, M. fuliginosus ; red kangaroo, M. rufus ), is related to climatic factors. All five species show trends in body size that conform with Bergmann's rule, individuals from colder environments being larger than those from warmer areas. The western and eastern grey kangaroos also conform with Allen's rule, the relative size of their extremities being large in warmer areas. In four of the five species (not the red kangaroo) body size is also correlated with indices of biomass productivity. However, since biomass productivity and ambient temperature are related to some extent, it is difficult to separate the effects of these factors.     

Thermoregulation by kangaroos from mesic and arid habitats: influence of temperature on routes of heat loss in eastern grey kangaroos (Macropus giganteus) and red kangaroos (Macropus rufus)

We examined thermoregulation in red kangaroos (Macropus rufus) from deserts and in eastern grey kangaroos (Macropus giganteus) from mesic forests/woodlands. Desert kangaroos have complex evaporative heat loss mechanisms, but the relative importance of these mechanisms is unclear. Little is known of the abilities of grey kangaroos. Our detailed study of these kangaroos' thermoregulatory responses at air temperatures (T(a)) from -5 degrees to 45 degrees C showed that, while some differences occur, their abilities are fundamentally similar. Both species show the basic marsupial characteristics of relatively low basal metabolism and body temperature (T(b)). Within the thermoneutral zone, T(b) was 36.3 degrees + or - 0.1 degrees C (X + or - SE) in both species, and except for a small rise at T(a) 45 degrees C, T(b) was stable over a wide range of T(a). Metabolic heat production was 25% higher in red kangaroos at T(a) -5 degrees C. At the highest T(a) (45 degrees C), both species relied on evaporative heat loss (EHL) to maintain T(b); both panting and licking were used. The eastern grey kangaroo utilised panting (76% of EHL) as the principal mode of EHL, and while this was so for red kangaroos, cutaneous evaporative heat loss (CEHL) was significant (40% of EHL). CEHL appeared to be mainly licking, as evidenced from surface temperatures. Both species utilised peripheral vascular adjustments to control heat flow, as indicated by changes in dry conductance (C(dry)). At lower temperatures, C(dry) was minimal, but it increased significantly at T(a) just below T(b) (33 degrees C); in these conditions, the C(dry) of red kangaroos was significantly higher than that of eastern grey kangaroos, indicating a greater reliance on dry heat loss. Under conditions where heat flows into the body from the environment (T(a) 45 degrees C), there was peripheral vasoconstriction to reduce this inflow; C(dry) decreased significantly from the values seen at 33 degrees C in both kangaroos. The results indicated that, while both species have excellent thermoregulatory abilities, the desert red kangaroos may cope better with more extreme temperatures, given that they respond to T(a) 45 degrees C with lower respiratory evaporation than do the eastern grey kangaroos.     

Free-ranging heart rate, body temperature and energy metabolism in eastern grey kangaroos (Macropus giganteus) and red kangaroos (Macropus rufus) in the arid regions of South East Australia

Eastern grey kangaroos (Macropus giganteus) are generally regarded as mesic inhabitants. Even though access to drinking water in permanent stock watering troughs is commonly available, these animals are still found in only low densities in arid pastoral areas. We hypothesised that the differential success of red and grey kangaroos in the arid zone may be due to higher energy requirements of M. giganteus with a concomitant need for increased food, rather than limitations imposed by inadequate water access. We set out to test this by indirectly measuring energy expenditure through the monitoring of heart rate by radio telemetry in semi-free-ranging eastern grey and red kangaroos (Macropus rufus). Radio telemetry measurements of heart rate were calibrated against oxygen consumption and were used in the assessment of energy expenditure of animals maintained in an 8-ha enclosure in the arid zone of southeast Australia. Heart rate provided a reliable estimate of oxygen consumption. This well-correlated relationship was curvilinear and was established for each individual. Behavioural observations revealed that both kangaroo species spent most of the day in low energy demanding activities. M. rufus were more active at night whilst M. giganteus were more active in the early mornings and late afternoons. Like other marsupials, both species had low field metabolic rates (FMRs). However, M. giganteus in keeping with their mesic history had higher FMRs than the more arid-adapted M. rufus, particularly during water restriction. Body temperature telemeters revealed a further species difference in that under hot conditions when water is freely available, M. rufus exhibits a higher and more labile daytime body temperature than M. giganteus. During the hottest part of the day M. giganteus maintain body temperature, relying upon increased evaporative cooling mechanisms, such as licking. Indeed, only when access to drinking water was restricted was thermolability evident in M. giganteus. Differences in behaviour and concomitant energy expenditure may thus contribute substantially to the divergent distribution and abundance of these two kangaroo species.     

Phylogeography of Eastern Grey Kangaroos,Macropus giganteus,Suggests a Mesic Refugium in Eastern Australia

Phylogeographic studies around the world have identified refugia where fauna were able to persist during unsuitable climatic periods, particularly during times of glaciation. In Australia the effects of Pleistocene climate oscillations on rainforest taxa have been well studied but less is known about the effects on mesic-habitat fauna, such as the eastern grey kangaroo (Macropus giganteus). The eastern grey kangaroo is a large mammal that is common and widespread throughout eastern Australia, preferring dry mesic habitat, rather than rainforest. As pollen evidence suggests that the central-eastern part of Australia (southeast Queensland and northern New South Wales) experienced cycles of expansion in mesic habitat with contraction in rainforests, and vice versa during glacial and interglacial periods, respectively, we hypothesise that the distribution of the eastern grey kangaroo was affected by these climate oscillations and may have contracted to mesic habitat refugia. From 375 mitochondrial DNA control region sequences from across the distribution of eastern grey kangaroos we obtained 108 unique haplotypes. Phylogenetic analysis identified two clades in Queensland, one of which is newly identified and restricted to a small coastal region in southern Queensland north of Brisbane, known as the Sunshine Coast. The relatively limited geographic range of this genetically isolated clade suggests the possibility of a mesic habitat refugium forming during rainforest expansion during wetter climate cycles. Other potential, although less likely, reasons for the genetic isolation of the highly distinct clade include geographic barriers, separate northward expansions, and strong local adaptation.     

Tooth wear in eastern grey kangaroos (Macropus giganteus) and western grey kangaroos (Macropus fuliginosus), and its potential influence on diet selection, digestion and population parameters

As teeth wear in eastern and western grey kangaroos, the pattern of enamel ridges changes. This affects the amount of available cutting edges and consequently the masticatory efficiency. These kangaroos also have molar progression. There is evidence for the independence of rates of tooth wear and molar progression, and variation is found in the maximum amount of wear attained by teeth both within and between populations. This variation has the potential to affect diet selection, digestion and population parameters.     

Sexual segregation in western grey kangaroos: testing alternative evolutionary hypotheses

In sexually dimorphic ungulates, sexual segregation is hypothesized to have evolved because of sex-specific differences in body size and/or reproductive strategies. We tested these alternative hypotheses in kangaroos, which are ecological analogues of ungulates. Kangaroos exhibit a wide range of body sizes, particularly among mature males, and so the effects of body size and sex can be distinguished. We tested predictions derived from these hypotheses by comparing the distribution of three sex–sex size classes of western grey kangaroos Macropus fuliginosus , in different habitats, and the composition of groups of kangaroos, across seasons. In accordance with the predation risk-reproductive strategy hypothesis, during the non-breeding season, females, which were more susceptible to predation than larger males, and were accompanied by vulnerable young-at-foot, were over-represented in secure habitats. Large males, which were essentially immune to predation, occurred more often than expected in nutrient-rich habitat, and small males, which faced competing demands of predator avoidance and feeding, were intermediate between females and large males in their distribution across habitats. During the breeding season, females continued to be over-represented in secure habitats when their newly emerged pouch young were most vulnerable to predation. All males occupied these same habitats to maximize their chances of securing mates. Consistent with the social hypotheses, groups composed of individuals of the same sex, irrespective of body size, were over-represented in the population during the non-breeding season, while during the breeding season all males sought females so that mixed-sex groups predominated. These results indicate that body size and reproductive strategies are both important, yet independent, factors influencing segregation in western grey kangaroos.     

Further studies of Dirofilaria roemeri (Nematoda: Filarioidea) in naturally and experimentally infected Macropodidae.

Larval development of D. roemeri occurs in the subcutaneous and intermuscular connective tissue and intramuscularly in the pelvic region and hind limbs of the wallaroo and eastern grey kangaroo. Host response to developing larvae is not evident at 1, 14 and 28 days. The development of D. roemeri in the red kangaroo exhibits features previously observed in both normal and abnormal hosts. Low-level blood microfilaraemia of brief duration occurs in the red kangaroo, which may act as a secondary reservoir of infection for other kangaroo and wallaby species. Among commercially harvested Macropodidae in Queensland there is a greater prevalence of D. roemeri in wallaroos and grey kangaroos than in red kangaroos. Infection is most prevalent in animals from south-central and south-western districts.     

Galactose-1 phosphate uridyl transferase deficiency in the western grey kangaroo (Macropus fuliginosus; marsupialia): a model system for gene therapy studies.

The western grey kangaroo (Macropus fuliginosus) was found to be deficient for galactose-1 phosphate uridyl transferase (GPUT). This species could be used therefore for studies of gene therapy techniques. An improved GPUT assay procedure was developed. It was found that phage particles injected intravenously remain in the blood of kangaroos until the particles are removed by the reticuloendothelial system or, if this system is overloaded, the particles are inactivated by the immune system four days later. No effective transgenosis was detected of the bacterial gal operon contained in the phage used.     

Lack of evidence for co-speciation in a parasitic nematode of grey kangaroos

Multilocus enzyme electrophoresis was used to compare specimens of the parasitic nematode Cloacina obtusa from the stomach of the eastern grey kangaroo, Macropus giganteus and the western grey kangaroo, M. fuliginosus. Allelic variation among nematodes was detected at 17 (85%) of 20 loci, but there was only a single fixed genetic difference (at the locus for isocitrate dehydrogenase, IDH) between C. obtusa from M. fuliginosus and those from M. giganteus in areas where each host occurred in allopatry. However, this fixed difference was not apparent within the zone of host sympatry. Although electrophoretic data indicate genetic divergence among allopatric populations of C. obtusa in the two host species, the magnitude of the electrophoretic difference (5%) between these populations does not refute the hypothesis that C. obtusa represents a single species. The 'usual' situation for parasitic helminths of grey kangaroos is that pairs of parasite species occur in the two host species. This situation differs for C. obtusa, where there has been a lack of speciation following a speciation event in its macropodid marsupial hosts. This finding suggests that a speciation event in the host does not necessarily lead to a speciation event for all its parasites and further highlights our lack of understanding of which processes drive speciation in parasites.     

Prevalence of Coxiella burnetii in western grey kangaroos (Macropus fuliginosus) in Western Australia

We investigated the role of the western grey kangaroo (Macropus fuliginosus) in the maintenance and transmission of Coxiella burnetii in Western Australia. Sera from 1,017 kangaroos were tested using an indirect enzyme-linked immunosorbent assay (ELISA) for the presence of C. burnetii antibodies. The overall antibody prevalence across 12 locations throughout mid- to southwestern Western Australia was 24.1% (95% CI: 21.6-26.8). Feces from 990 of the same animals were tested using PCR to identify active shedding of C. burnetii in excreta. Coxiella burnetii DNA was detected in 4.1% (95% CI: 3.1-5.6) of samples. Our results suggest that kangaroos are reservoirs for C. burnetii in Western Australia and may contribute to transmission of the organism to domestic livestock and humans.     

Dominance and association among members of a captive and a free-ranging group of grey kangaroos (Macropus giganteus)

Dominance relationships and the degree of association between members of groups of eastern grey kangaroos (Macropus giganteus) were investigated by observing a small group in captivity and a larger free-ranging group. Only decisive aggressive interactions were used as a criterion of dominance, and the number of times individuals occurred together were used as a measure of association. A dominance hierarchy in which the male assumed the highest rank was found in the captive group, while in the wild hierarchies were found separately among both males and females in the group. A low level of positive association existed between members of both the groups studied and the data indicated that in general the free ranging animals tended to move about at random with respect to each other. In the captive group dispersion about the enclosure was regular but became more random during the day in winter and spring.     

Energy, water and space use by free-living red kangaroos Macropus rufus and domestic sheep Ovis aries in an Australian rangeland

We used doubly labelled water to measure field metabolic rates (FMR) and water turnover rates (WTR) in one of Australia’s largest native herbivores, the red kangaroo (Macropus rufus) and one of Australia’s dominant livestock species, the wool-breed Merino sheep, under free-living conditions in a typical Australian rangeland. Also, we used GPS technology to examine animal space use, along with the comparisons of urine concentration, diet, diet digestibility, and subsequent grazing pressures. We found smaller space-use patterns than previously reported for kangaroos, which were between 14 and 25 % those of sheep. The FMR of a 25-kg kangaroo was 30 % that of a 45-kg sheep, while WTR was 15 % and both were associated with smaller travel distances, lower salt intakes, and higher urine concentration in kangaroos than sheep. After accounting for differences in dry matter digestibility of food eaten by kangaroos (51 %) and sheep (58 %), the relative grazing pressure of a standard (mature, non-reproductive) 25-kg kangaroo was 35 % that of a 45-kg sheep. Even for animals of the same body mass (35 kg), the relative grazing pressure of the kangaroo was estimated to be only 44 % that of the sheep. After accounting for the energetic costs of wool growth by sheep, the FMRs of our sheep and kangaroos were 2–3 times their expected BMRs, which is typical for mammalian FMR:BMRs generally. Notably, data collected from our free-living animals were practically identical to those from animals confined to a semi-natural enclosure (collected in an earlier study under comparable environmental conditions), supporting the idea that FMRs are relatively constrained within species.     

Brain thermal inertia,but no evidence for selective brain cooling,in free-ranging western grey kangaroos (<Emphasis Type="Italic">Macropus fuliginosus</Emphasis>)

Marsupials reportedly can implement selective brain cooling despite lacking a carotid rete. We measured brain (hypothalamic) and carotid arterial blood temperatures every 5 min for 5, 17, and 63 days in spring in three free-living western grey kangaroos. Body temperature was highest during the night, and decreased rapidly early in the morning, reaching a nadir at 10:00. The highest body temperatures recorded occurred sporadically in the afternoon, presumably associated with exercise. Hypothalamic temperature consistently exceeded arterial blood temperature, by an average 0.3°C, except during these afternoon events when hypothalamic temperature lagged behind, and was occasionally lower than, the simultaneous arterial blood temperature. The reversal in temperatures resulted from the thermal inertia of the brain; changes in the brain to arterial blood temperature difference were related to the rate of change of arterial blood temperature on both heating and cooling (P < 0.001 for all three kangaroos). We conclude that these data are not evidence for active selective brain cooling in kangaroos. The effect of thermal inertia on brain temperature is larger than might be expected in the grey kangaroo, a discrepancy that we speculate derives from the unique vascular anatomy of the marsupial brain.     

Proteins of marsupial erythrocyte membranes

The proteins of erythrocyte membranes from the red kangaroo, western grey kangaroo, eastern grey wallaroo (euro), red-necked wallaby, Tammar wallaby, and brush-tail possum have been fractionated on acrylamide gels in the presence of sodium dodecyl sulfate. The pattern of proteins was remarkably similar between the different marsupial species. The pattern of Coomassie blue-staining proteins in the membranes of these species was also very similar to that of the human erythrocyte membrane. However, the glycoproteins in the marsupial erythrocyte membranes were markedly less conspicuous than those of the human erythrocyte membrane. Furthermore, the mobilities of the glycoproteins from the marsupials were different from those of the human erythrocyte membrane. The erythrocytes of the western grey kangaroo, the eastern wallaroo and the red-necked wallaby showed pronounced resistance to hypotonic lysis compared with those of the Tammar wallaby and the human. This effect seems to be related to the size of the erythrocytes rather than to differences in their protein composition.     

Host-parasite associations of Eimeria spp. (Apicomplexa:Eimeriidae) in kangaroos and wallabies of the genus Macropus (Marsupialia:Macropodidae)

Faecal samples from 514 kangaroos and wallabies representing 12 species of the genus Macropus were examined for oocysts of Eimeria spp. Six species of Eimeria were redescribed from their type hosts, and on the basis of finding homologous oocysts in the faeces of other Macropus spp., host ranges for these coccidia were extended. Eimeria hestermani Mykytowycz, 1964 is redescribed from M. giganteus (eastern grey kangaroo) and is described from M. fuliginosus (western grey kangaroo), M. rufogriseus (red-necked wallaby), M. dorsalis (black-striped wallaby), and M. eugenii (tammar wallaby). E. toganmainensis Mykytowycz, 1964 is redescribed from M. rufus (red kangaroo) and the host range is extended to M. giganteus, M. fuliginosus, M. rufogriseus and M. eugenii. E. wilcanniensis Mykytowycz, 1964 is redescribed from M. rufus, and the host range is extended to M. giganteus, M. fuliginosus and M. robustus (euro or wallaroo). E. macropodis Wenyon & Scott, 1925 is redescribed from M. rufogriseus, and is described from M. giganteus, M. fuliginosus, M. rufus, M. irma (western brush wallaby), M. parryi (whip-tailed wallaby), M. dorsalis, M. eugenii, and M. parma (parma wallaby). E. fausti Yakimoff & Matschoulsky, 1936, E. cunnamullensis Mykytowycz, 1964 and E. purchasei Mykytowycz, 1964 are synonymized with E. macropodis. E. marsupialium Yakimoff & Matschoulsky, 1936 is redescribed from M. giganteus, and from M. fuliginosus. E. gungahlinensis Mykytowycz, 1964 is redescribed from M. fuliginosus, and from M. giganteus. Seven new species of Eimeria are described. E. flindersi, new species, is described from M. eugenii, M. rufogriseus, and M. antilopinus (antilopine wallaroo). E. prionotemni, new species, is described from M. eugenii, M. parryi, M. rufogriseus, M. agilis (agile wallaby) and M. dorsalis. E. mykytowyczi, new species, is described from M. agilis, M. antilopinus, and M. parryi. E. parryi, new species, is described from M. parryi. E. yathongensis, new species, is described from M. fuliginosus and M. giganteus. E. parma, new species, is described from M. parma, and E. desmaresti, new species, is described from M. rufogriseus. E. kogoni Mykytowycz, 1964, and E. rufusi Prasad, 1960 are considered species inquirendae. The host-parasite associations of these coccidia, and of similar species of Eimeria in other genera of Macropodoid marsupials, are discussed in relation to the postulated phylogeny of the hosts.     

Inter‐ and intraspecific effects of body size on habitat use among sexually‐dimorphic macropodids

Body size affects key life‐history parameters including dietary requirements and predation risk. We examined these effects on diel habitat use in a community of three sexually‐dimorphic macropodid marsupial species: western grey kangaroo Macropus fuliginosus, red‐necked wallaby M. rufogriseus and swamp wallaby Wallabia bicolor. In particular, our study seeks evidence of these effects operating concurrently at the intra‐ and interspecific levels. We used radio‐tracking to quantify habitat use and characterised each used location by recording the cover of plant functional groups and the presence of plant species. During nocturnal foraging periods we predicted that smaller animals (between and within species) should use habitats with higher‐quality forage, which is often less abundant, than larger animals, as metabolic demand scales with body size. During diurnal resting periods we predicted that smaller animals (between and within species), being more vulnerable to predation, should use greater concealment cover than larger animals. Western grey kangaroos and swamp wallabies behaved as predicted during foraging periods, but red‐necked wallabies did not, using more open, poorer‐quality habitats than expected. Only western grey kangaroos showed a within‐species effect on habitat use: the relatively smaller females foraged in higher‐quality patches. Habitats used by animals during the resting period generally offered greater concealment cover than those used during the foraging period, but there were no clear body size effects on the density of vegetation used. In our system, body size alone could not explain all of the observed patterns, suggesting that there may also be individual differences in habitat requirements influenced by factors such as reproductive costs, predation risk and social facilitation.