The cognitive abilities of many non-human animals have been investigated in recent years; however, outside of laboratory rodent strains, it is largely unknown how direct and indirect genetic factors influence the development of cognition. In a previous study, we found no impact of maternal genetic or non-genetic effects on problem solving in the fawn-footed mosaic-tailed rat Melomys cervinipes. However, cognition is multifaceted, and different forms of cognition may not all be influenced by the same factors. Therefore, we investigated whether maternal genetic and non-genetic effects affected the development of multiple, different measures of cognition in the fawn-footed mosaic-tailed rat. We first measured the amount of maternal care mothers provided to their offspring and then tested mothers and offspring as adults in three tests: an associative memory test, a novel object recognition test, and a food extraction task (to assess learning). We assessed whether the maternal care provided by mothers influenced cognition and used parent-offspring regressions to determine whether the cognitive abilities of individuals had a heritable component. Offspring that received more indirect care were significantly more likely to learn the lever task than offspring that received less indirect care, possibly because this task required more neurological processing for successful completion than the other tests. No other measure of maternal care significantly influenced offspring cognition, and offspring cognition did not appear to have a heritable component. This suggests that cognitive development in this species is likely quite flexible, and that maternal direct and indirect genetic effects may not play a significant role in the development of cognition.

Context Rainforests typically evolved without the influence of fire or with only low-intensity fires, making them vulnerable to contemporary increases in fire frequency and intensity. Rainforest-associated species are predicted to be less adaptable than generalist species, but little is known about how fire in rainforest margins affects their habitat use and behaviour. Aims We investigated how mammal community composition, diversity, probability of habitat use and probability of movement were affected by wildfires that occurred in rainforest margins in South East Queensland, Australia, in 2019–20. Methods We deployed camera traps at 23 sites spanning the following three fire-habitat categories: unburnt rainforest (UR), burnt rainforest (BR) and surrounding burnt sclerophyll forest (BS), and used passive detection to analyse habitat use and behaviour. Key results Fire-habitat category had little influence on community composition. Species diversity was highest in unburnt rainforest compared with burnt rainforest and surrounding burnt sclerophyll forest. The probability of habitat use was highest in unburnt rainforest for both the long-nosed bandicoot (Perameles nasuta, estimated mean probability (95% CI): UR = 57.1% (22.98, 85.6), BR = 0%, BS = 0%) and the fawn-footed melomys (Melomys cervinipes: UR = 100%, BR = 87.5% (46.3, 98.3), BS = 50% (20.0, 80.0)). Probability of movement for the bush rat (Rattus fuscipes) increased with increasing elevation in burnt sclerophyll and was unaffected by elevation in unburnt and burnt rainforest. Conclusions Rainforest margins that experienced wildfire had reduced species diversity, most likely owing to a reduction in habitat use by rainforest-associated species. Movement patterns of mammal species were complex and not consistently related to recent fire history. Implications Rainforest margins and associated species are likely to be negatively affected by increasing wildfire intensity and frequency. In addition to urgent climate-change mitigation, land management that prevents wildfire incursion is likely to benefit rainforest communities in future.

Abstract Personality in non-human animals has been a popular area of research; however, it is still unknown how genetic and non-genetic factors influence the development of personality in many species. Therefore, we investigated how maternal genetic and non-genetic effects influenced adult offspring personality (exploration and anxiety) in the fawn-footed mosaic-tailed rat Melomys cervinipes. We first measured the amount of maternal care mothers provided to their offspring. Later, we assessed mothers and adult offspring over two testing sessions for exploratory behaviour using open field and novel object tests, and anxiety behaviour in a light/dark test. We calculated repeatability of behaviours and used parent–offspring regressions to assess heritability of behaviours. No measure of maternal care significantly influenced offspring personality. However, exploration of new spaces was constrained by maternal genetic effects. In contrast, anxiety and exploration of novel objects was more flexible, suggesting these behaviours may be more influenced by an individual’s experiences during development.

The consistency of exploration behaviours across life stages in a native Australian rodent, the fawn-footed mosaic-tailed rat Melomys cervinipes.

The gut microbiota are critical for maintaining the health and physiological function of individuals. However, illness and treatment with antibiotics can disrupt bacterial community composition, the consequences of which are largely unknown in wild animals. In this study, we described and quantified the changes in bacterial community composition in response to illness and treatment with antibiotics in a native Australian rodent, the fawn-footed mosaic-tailed rat (Melomys cervinipes). We collected faecal samples during an undiagnosed illness outbreak in a captive colony of animals, and again at least one year later, and quantified the microbiome at each time point using 16s ribosomal rRNA gene sequencing. Gut bacterial composition was quantified at different taxonomic levels, up to family. Gut bacterial composition changed between time periods, indicating that illness, treatment with antibiotics, or a combination affects bacterial communities. While some bacterial groups increased in abundance, others decreased, suggesting differential effects and possible co-adapted and synergistic interactions. Our findings provide a greater understanding of the dynamic nature of the gut microbiome of a native Australian rodent species and provides insights into the management and ethical well-being of animals kept under captive conditions.

The gut microbiota are critical for maintaining the health and physiological function of individuals. However, illness and treatment with antibiotics can disrupt bacterial community composition, the consequences of which are largely unknown in wild animals. In this study, we described and quantified the changes in bacterial community composition in response to illness and treatment with antibiotics in a native Australian rodent, the fawn-footed mosaic-tailed rat (Melomys cervinipes). We collected faecal samples during an undiagnosed illness outbreak in a captive colony of animals, and again at least one year later, and quantified the microbiome at each time point using 16s ribosomal rRNA gene sequencing. Gut bacterial composition was quantified at different taxonomic levels, up to family. Gut bacterial composition changed between time periods, indicating that illness, treatment with antibiotics, or a combination affects bacterial communities. While some bacterial groups increased in abundance, others decreased, suggesting differential effects and possible co-adapted and synergistic interactions. Our findings provide a greater understanding of the dynamic nature of the gut microbiome of a native Australian rodent species and provides insights into the management and ethical well-being of animals kept under captive conditions.

This study tested the utility of a rope bridge across a road that traversed restored rainforest habitat (5–8 years old) to assess the use of these new habitats by arboreal mammals. Camera-trapping revealed common brushtail possums (Trichosurus vulpecula), green ringtail possums (Pseudochirops archeri) and Herbert River ringtail possums (Pseudochirulus herbertensis) used the rope bridge regularly while striped possums (Dactylopsila trivirgata), fawn-footed melomys (Melomys cervinipes), long-tailed pygmy-possums (Cercartetus caudatus) and Lumholtz’s tree-kangaroos (Dendrolagus lumholtzi) were recorded at the bridge accesses, but no crossings could be proven. No Lemuroid ringtail possums (Hemibelideus lemuroides) were recorded near the rope bridge. Differences in the use of the restored rainforest habitat and the crossing structure are likely to be caused by differences in the species’ reliance on features in mature forests, and their responses to rainforest edges. The results support the utility of canopy crossing structures to facilitate the use of restored habitat by arboreal mammals.

Problem solving ability is affected by many factors, including physiology, personality, and cognition. However, how age and experience influence problem-solving ability during development is harder to untangle. We tested how age and experience affected problem solving in a native Australian rodent, the fawn-footed mosaic-tailed rat Melomys cervinipes. Juveniles were divided into two groups (different ages at start of testing) and then received a food-baited cardboard matchbox every 10days for a total of three tests. We compared the problem-solving ability of individuals from both groups, which allowed us to separate the effects of age and experience. Juveniles with more experience solved the task faster than juveniles with less experience. Furthermore, inexperienced older juveniles interacted with the problems more than inexperienced younger juveniles. Previous solving experience may be important for short-term solving success, while age, in the absence of experience, might be associated with increased exploration, leading to increased investigation of novel problems. Previous experience at manipulating objects generally may also be important for problem-solving success, which likely provides an advantage as resources and habitats change seasonally and annually.

Innovative problem solving is thought to be a flexible trait that allows animals to adjust to changing or challenging environmental conditions. However, it is not known how problem solving develops during an animal's early life, or whether it may have a heritable component. We investigated whether maternal genetic and nongenetic effects influenced problem‐solving ability in a native Australian rodent, the fawn‐footed mosaic‐tailed rat Melomys cervinipes. We measured direct (time spent grooming and huddling), indirect (time spent nesting), and total amount of maternal care received across pup development (postnatal Days 1–13). We measured problem solving in juveniles using matchbox tasks, and in mothers and adult offspring using six tasks of varying complexity (matchbox, cylinder, obstruction, pillar, tile, and lever tasks). We found no relationship between any maternal care measures and problem‐solving abilities across multiple tests, suggesting limited (if any) maternal nongenetic effects. We also found that, as shown by low heritability estimates, problem solving only had a small heritable component in some tasks, but this was nonsignificant and requires further investigation. These results suggest that problem solving is unlikely to be constrained by maternal effects experienced during early development, and is, instead, more likely to be influenced by other factors (e.g., experience) later in an individual's lifetime.

Animals can respond physiologically, such as by adjusting glucocorticoid hormone concentrations, to sudden environmental challenges. These physiological changes can then affect behavioural and cognitive responses. While the relationships between adrenocortical activity and behaviour and cognition are well documented, results are equivocal, suggesting species-specific responses. We investigated whether adrenocortical activity, measured using corticosterone metabolite concentration, was related to problem solving in an Australian rodent, the fawn-footed mosaic-tailed rat (Melomys cervinipes). Mosaic-tailed rats live in complex environments that are prone to disturbance, suggesting a potential need to solve novel problems, and have been found to show relationships between physiology and other behaviours. We measured problem solving using five food-baited puzzles (matchbox and cylinder in the home cage, and activity board with pillars to push, tiles to slide and levers to lift in an open field), and an escape-motivated obstruction task in a light/dark box. Faecal samples were collected from individuals during routine cage cleaning. Adrenocortical activity was evaluated non-invasively by measuring faecal corticosterone metabolites using an enzyme immunoassay, which was biochemically and biologically validated. Despite varying over time, adrenocortical activity was not significantly related to problem solving success or time spent interacting for any task. However, as adrenocortical activity is reflective of multiple physiological processes, including stress and metabolism, future studies should consider how other measures of physiology are also linked to problem solving.

Problem solving is important for survival, allowing animals to access novel food resources or escape from predators. It was originally thought to rely on an animal's intelligence; however, studies examining the relationship between individual cognitive ability and problem solving performance show mixed results, and studies are often restricted to only one cognitive and one problem solving task. We investigated the relationship between general cognitive ability and problem solving across multiple tasks in the fawn-footed mosaic-tailed rat Melomys cervinipes. We measured general cognitive ability across different domains (memory in an odour learning association task, recognition in a novel object recognition task, size discrimination using different sized pieces of food, and learning across multiple presentations of a food-baited activity board). We also measured problem solving across different contexts (food-baited puzzle boxes in home cage, obstruction task, and food-baited activity board in a novel arena). Mosaic-tailed rats showed a general cognitive ability, with average problem solving latency, memory ability, and learning in the tile task being correlated. As such, individuals that were able to remember an association and learned to solve the tile task solved the problems faster than individuals that could not remember or learn. Our results suggest that problem solving in mosaic-tailed rats likely relies on some forms of simple cognition, particularly memory, but could also depend on other traits, such as an individual's persistence.

Abstract The relationship between an animal's personality and its problem solving ability has become a popular topic of investigation. However, results are conflicting, suggesting that these relationships may be species‐specific. We investigated these relationships in a native Australian rodent, the fawn‐footed mosaic‐tailed rat (Melomys cervinipes). We predicted that more exploratory and less anxious mosaic‐tailed rats would be better problem solvers (e.g. faster to solve the problem) as they would interact with the puzzles more and would be more willing to engage with the task. We assessed personality across two contexts (exploration in an open field and novel object test, and anxiety under simulated predation risk in a light/dark box) and over time (three repetitions). We measured problem solving using two food‐baited puzzle boxes (matchbox and cylinder), a Trixie Dog Activity Board with three problems (pillars, tiles and levers) and an obstruction task. Individual mosaic‐tailed rats showed consistent individual differences in personality, but not problem solving ability. Furthermore, we found a positive relationship between personality and problem solving ability, with more exploratory individuals solving more problems, and solving problems faster, than less exploratory individuals. Exploratory individuals could be better problem solvers because they are more willing to interact with objects and are less neophobic than less exploratory individuals. However, less exploratory individuals still persist in the population, possibly due to differences in cognitive abilities, such as discrimination or recognition, that allow them to compensate for poorer problem solving abilities.

A single Eastern Grass Owl Tyto longimembris was observed in Bundjalung National Park, New South Wales, in September 2019. Pellets (n = 17) collected from its roost contained the remains of House Mouse Mus musculus, Grassland Melomys Melomys burtoni, Black Rat Rattus rattus, Swamp Rat R. lutreolus, Fawn-footed Melomys Melomys cervinipes, Common Planigale Planigale maculata, Eastern Blossom Bat Syconycteris australis and honeyeater Phylidonyris sp. The most interesting findings were the Eastern Blossom Bat (the first published record of a bat in the diet of an Eastern Grass Owl in Australia) and that one of the Grassland Melomys specimens had pink bones.

Habitat complexity reflects resource availability and predation pressure – both factors that influence behaviour. We investigated whether exploratory behaviour and activity varied in fawn-footed mosaic-tailed rats (Melomys cervinipes) from two habitats that were categorised differently based on vegetation. We conducted vegetation surveys to determine structural complexity and vegetation cover, confirming that an abandoned hoop-pine (Araucaria cunninghami) plantation forest was structurally less complex, with lower vegetation cover than a variable secondary rainforest. We then tested mosaic-tailed rats from both sites in four behavioural tests designed to assess exploratory and activity behaviours (open field, novel object, light-dark box, acoustic startle), predicting that rats from the less structurally complex habitat would be less exploratory, and show lower activity. Our results provide some evidence for a context-specific trade-off between exploratory behaviour and predation risk in rats from the abandoned hoop pine plantation, as rats were less active, and showed a freezing strategy in the light-dark box. We also found context-specific sex differences in behaviour in response to a novel object and sound. Our results suggest that small-scale variation in habitat structure and complexity, as well as sex differences, is associated with variation in behaviour, most likely through effects on resource availability and/or predation risk.

The fawn-footed mosaic-tailed rat (Melomys cervinipes) is a common Australian rainforest rodent; however, little is known about the growth or behavioural development of individuals of this species. We raised mosaic-tailed rats in captivity to assess the growth and behavioural development of pups from birth until weaning. Pups developed quickly compared with some other Australian species, and there were no significant differences in growth between males and females, except for anogenital distance. The auditory meatus was open by Postnatal Day 5, and eyes were fully opened by Postnatal Day 9. All behaviours, including righting, locomotion, negative geotaxis, climbing and grip reflex, were fully developed by Postnatal Day 6. These results suggest that mosaic-tailed rats are semiprecocial in their physical and behavioural development compared with some native Australian rodent species that are found in arid environments. As females produce few, relatively well-developed young, the population has a low intrinsic rate of natural increase. This may, however, be offset by mosaic-tailed rats producing more litters per year. Understanding the biology of mosaic-tailed rats in general could provide insights into how rarer precocial species might struggle to increase in population size under increasing disturbances.

Innovation is the ability to use a new behaviour, or use an existing behaviour in a new context. Innovation, as an aspect of behavioural flexibility, could be important for allowing animals to cope with rapid environmental changes. Surprisingly, few studies have focused on how innovation ability is affected by task complexity. We investigated innovation ability across multiple tasks of varying complexity in a native Australian rodent, the fawn-footed mosaic-tailed rat (Melomys cervinipes). We predicted that mosaic-tailed rats would be capable of innovating because they live in complex habitats and can exploit disturbed and changing environments. However, we also predicted that the success rate of innovating would decrease as task complexity increased. Mosaic-tailed rats were exposed to six novel problems: cylinder, matchbox, obstruction test, pillar, tile and lever (the last three presented in a Trixie dog activity board), which represented increasing complexity. We counted the number of individuals that could solve at least one task, compared individuals for solving efficiency and latency to solve, and compared the solving success of each task. All mosaic-tailed rats could innovate. However, solving success differed between individuals, with some solving every task and others only solving one. Solving success rate was significantly higher in the simplest task (pillar) compared to the most complicated task (lever). There was no effect of sex or sampling condition on innovation. This study is the first to demonstrate innovation ability across task complexity in an Australian rodent and provides promising avenues for future studies of innovation.

Abstract Rodents rely on their sensitive olfactory systems to detect and respond to predators. We investigated the ability of a native Australian rodent, the fawn-footed mosaic-tailed rat Melomys cervinipes, to detect, recognise, and discriminate between two species of native snakes. We used snake sheds from a sympatric venomous red-bellied black snake Pseudechis porphyriacus and a non-sympatric non-venomous Stimson’s python Antaresia stimsoni. 20 mosaic-tailed rats each experienced three olfactory tests using a Y-maze. Rats were first exposed to one snake shed against a paper control, and then exposed to the other snake shed against a paper control. Which rat experienced which shed first was allocated randomly. Mosaic-tailed rats were then exposed to both sheds simultaneously. Rats could detect the snake sheds, spending longer investigating, and making more visits to, the sheds than the paper control. They also recognised the sheds as potentially dangerous, reducing their total investigation over time, but increasing their frequency of visits. However, rats did not discriminate between sheds, suggesting a general strategy for assessing the identity of reptilian predators.

Melomys cervinipes (Gould, 1852) is a murid rodent commonly called the fawn-footed mosaic-tailed rat. A small, russet brown rodent with light fawn-colored feet, it is 1 of 21 currently recognized species in the genus Melomys. The species is endemic to Australia, occurring in the rainforests and forests along the eastern coast. M. cervinipes is listed as "Least Concern" by the International Union for the Conservation of Nature and Natural Resources.

The black-tailed dusky antechinus (Antechinus arktos) is an endangered, small carnivorous marsupial endemic to Australia, which occurs at low population density along with abundant sympatric populations of other small mammals: Antechinus stuartii, Rattus fuscipes and Melomys cervinipes. Using A. arktos as a model species, we aimed to evaluate the effectiveness of infrared digital camera traps for detecting and differentiating small mammals and to comment on the broad applicability of this methodology. We also sought to understand how the detection probabilities of our target species varied over time and characterize their activity patterns. We installed 11 infrared cameras at one of only three known sites where A. arktos occurs for five consecutive deployments. Cameras were fixed to wooden stakes and oriented vertically, 35 cm above ground, directly facing bait containers. Using this method, we successfully recorded and identified individuals from all four species of small mammal known previously in the area from live trapping, including A. arktos. This validates the effectiveness of the infrared camera type and orientation for small mammal studies. Periods of activity for all species were highly coincident, showing a strong peak in activity during the same two-hour period immediately following sunset. A. arktos, A. stuartii and M. cervinipes also displayed a strong negative linear relationship between detection probability and days since deployment. This is an important finding for camera trapping generally, indicating that routine camera deployment lengths (of one-to-two weeks) between baiting events may be too long when targeting some small mammals.

Abstract AimOur aim was to clarify the lineage‐level relationships for Melomys cervinipes and its close relatives and investigate whether the patterns of divergence observed for these wet‐forest‐restricted mammals may be associated with recognized biogeographical barriers.LocationMesic closed forest along the east coast of Australia, from north Queensland to mid‐eastern New South Wales.MethodsTo enable rigorous phylogenetic reconstruction, divergence‐date estimation and phylogeographical inference, we analysed DNA sequence and microsatellite data from 307 specimens across the complete distribution of M. cervinipes (45 localities).ResultsThree divergent genetic lineages were found within M. cervinipes, corresponding to geographically delineated northern, central and southern clades. Additionally, a fourth lineage, comprising M. rubicola and M. capensis, was identified and was most closely related to the northern M. cervinipes lineage. Secondary contact of the northern and central lineages was identified at one locality to the north of the Burdekin Gap.Main conclusionsContemporary processes of repeated habitat fragmentation and contraction, local extinction events and subsequent re‐expansion across both small and large areas, coupled with the historical influence of the Brisbane Valley Barrier, the St Lawrence Gap and the Burdekin Gap, have contributed to the present phylogeographical structure within M. cervinipes. Our study highlights the need to sample close to the periphery of putative biogeographical barriers or risk missing vital phylogeographical information that may significantly alter the interpretation of biogeographical hypotheses.