Melomys Burtoni Research Articles

Pyrodiversity trade-offs: A simulation study of the effects of fire size and dispersal ability on native mammal populations in northern Australian savannas

Maximising the spatiotemporal variability of prescribed fire (i.e. pyrodiversity) is often thought to benefit biodiversity. However, given mixed empirical support, the generality of the pyrodiversity hypothesis remains questionable. Here, we use a simulation experiment to explore the effects of spatiotemporal fire patterns on the population trajectories of four mammal species in a northern Australian savanna: northern brown bandicoot (Isoodon macrourus), northern brushtail possum (Trichosurus vulpecula arnhemensis), grassland melomys (Melomys burtoni), and northern quoll (Dasyurus hallucatus). Underpinned by data from a landscape-scale fire experiment, we simulated mammal population trajectories under three scenarios of fire size (ambient, small/dispersed fires, large/clumped fires) and three levels of dispersal ability (low, moderate, high) over a 21-year period across the Kapalga area of Kakadu National Park. The simulated population size of all four species declined markedly, regardless of fire spatial pattern and dispersal ability. However, the predicted final population size (i.e. number of individuals in the final timestep of the simulation) for the northern brown bandicoot, northern brushtail possum and grassland melomys were significantly influenced by fire size, with declines most severe under the small/dispersed fire scenario. Our results suggest that maximising the dispersion of small fires at the expense of disturbance refugia (such as less-frequently burnt areas) may exacerbate the severity of mammal decline. This highlights the importance of considering trade-offs between spatial (i.e. fire dispersion) and temporal (i.e. fire frequency) aspects of pyrodiversity, and the potential risks when applying fire management for biodiversity conservation without a firm understanding of the requirements of the target species.

Rodents may be important pollinators of banksias in subtropical Australia

Knowledge of the role of non-flying mammals in the pollination of the Australian flora is still incomplete. We captured non-flying mammals visiting Banksia ericifolia in north-east New South Wales and sampled pollen from their heads. The grassland melomys (Melomys burtoni) was captured >4 times more often than the house mouse (Mus musculus) or the swamp rat (Rattus lutreolus). Nocturnal pollen loads (mean 295 ± 53 grains) measured on the melomys are among the highest for an Australian non-flying mammal. Pollen removal from flowers at night was widespread. These observations suggest the grassland melomys is likely to play an important role in the pollination of subtropical B. ericifolia.

The fungal rat race: mycophagy among rodent communities in eastern Australia

Context Rodents in many parts of the world perform an important ecosystem function as dispersers of mycorrhizal fungal spores. These fungi are vital to nutrient uptake in plant communities, but many of the fungal taxa that form these associations have fruiting bodies that are reliant on animals for their spore dispersal. Aims Numerous studies have focused on the ecological importance of Australian marsupials (especially members of the Potoroidae) for the dispersal of these ecologically important fungi. We chose to focus this study on the role of murid rodents in the dispersal of these fungi in eastern Australia. Methods To compare fungal taxa in murid diets, we trapped rodents in three regions of eastern Australia; our study sites spanned over 2000 km from temperate eucalypt forests to tropical eucalypt and tropical rainforest habitats. We performed microanalysis on all scats to determine whether fungi were consumed and which taxa were being eaten. Statistical analysis was conducted to investigate trends in levels of mycophagy among species and habitats. Key results We examined 10 rodent species, and all were shown to ingest mycorrhizal fungi to varying degrees. The diversity, abundance and specific fungal taxa consumed varied depending on the site and forest type. In drier forests dominated by Eucalyptus spp., the fungal taxa consumed and dispersed were primarily ectomycorrhizal; in wetter rainforest habitats, the fungal diversity consumed was far lower and included primarily vesicular arbuscular fungi. We provide the first evidence of mycophagy by grassland melomys (Melomys burtoni) and Cape York melomys (Melomys capensis). Conclusions Our findings highlight the importance of rodents as dispersers of mycorrhizal fungi across a variety of habitats from temperate to tropical forests of eastern Australia. Implications This study increases the existing knowledge of rodent diets and habitat requirements. It also provides a new angle for mammal conservation efforts, given the vital nature of the ecosystem service provided by these small and frequently overlooked mammals.

Trophic cascade driven by behavioral fine-tuning as naïve prey rapidly adjust to a novel predator.

The arrival of novel predators can trigger trophic cascades driven by shifts in prey numbers. Predators also elicit behavioral change in prey populations, via phenotypic plasticity and/or rapid evolution, and such changes may also contribute to trophic cascades. Here, we document rapid demographic and behavioral changes in populations of a prey species (grassland melomys Melomys burtoni, a granivorous rodent) following the introduction of a novel marsupial predator (northern quoll Dasyurus hallucatus). Within months of quolls appearing, populations of melomys exhibited reduced survival and population declines relative to control populations. Quoll-invaded populations were also significantly shyer than nearby, quoll-free populations of conspecifics. This rapid but generalized response to a novel threat was replaced over the following 2 yr with more threat-specific antipredator behaviors (i.e., predator-scent aversion). Predator-exposed populations, however, remained more neophobic than predator-free populations throughout the study. These behavioral responses manifested rapidly in changed rates of seed predation by melomys across treatments. Quoll-invaded melomys populations exhibited lower per-capita seed take rates, and rapidly developed an avoidance of seeds associated with quoll scent, with discrimination playing out over a spatial scale of tens of meters. Presumably the significant and novel predation pressure induced by quolls drove melomys populations to fine-tune behavioral responses to be more predator specific through time. These behavioral shifts could reflect individual plasticity (phenotypic flexibility) in behavior or may be adaptive shifts from natural selection imposed by quoll predation. Our study provides a rare insight into the rapid ecological and behavioral shifts enacted by prey to mitigate the impacts of a novel predator and shows that trophic cascades can be strongly influenced by behavioral as well as numerical responses.

Diet of an Eastern Grass Owl Tyto longimembris in northern New South Wales

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.

Investigating the effects of fire management on savanna biodiversity with grid‐based spatially explicit population simulations

Abstract The development of effective fire management for biodiversity conservation is a global challenge. The highly dynamic nature of fire, the difficulty in replicating ‘real‐world’ fire experiments and the need to understand population changes at large spatiotemporal scales make computer simulations particularly useful for identifying optimal fire management regimes for biodiversity conservation. We aimed to develop a flexible modelling approach with which to investigate how the spatiotemporal application of fire (i.e. management scenarios) influences savanna biodiversity. We used existing data from a landscape‐scale fire experiment to develop population simulations for the common brushtail possum Trichosurus vulpecula, grassland melomys Melomys burtoni and northern brown bandicoot Isoodon macrourus across the Kapalga area of Kakadu National Park in northern Australia. We simulated how populations were expected to change between 1995 and 2015 in response to the fire patterns observed at Kapalga over this period, and under a hypothetical management scenario of extensive prescribed burning. Our models predicted a substantial decline in all three species in response to the observed fire regime at Kapalga, suggesting that the fire patterns observed at Kapalga, with the associated mechanisms and interactions with other ecological processes, were not conducive with the persistence of native mammal populations. Our prescribed burning scenario had little effect on the predicted population trajectory of the common brushtail possum and grassland melomys, but markedly improved the population trajectory of the northern brown bandicoot. These inconsistencies highlight the need for a nuanced approach to fire management across northern Australian savannas, that is tailored to local conditions and management objectives. Synthesis and applications. The modelling approach outlined here provides a basis for identifying fire patterns that are beneficial for conserving biodiversity, thereby increasing our capacity to establish clear targets for prescribed fire management. Importantly, this approach is flexible and can be easily adapted to other taxa and fire‐prone ecosystems.

Bias averted: personality may not influence trappability

If bold animals are more likely to be trapped than shy animals, we take a biased sample of personalities—a problem for behavioural research. Such a bias is problematic, also, for population estimation using mark-recapture models that assume homogeneity in detection probabilities. In this study, we investigated whether differences in boldness result in differences in detection probability in a native Australian rodent, the grassland melomys (Melomys burtoni). During a mark-recapture study of this species, we used modified open field tests to assess the boldness (via emergence, and interaction with a novel object) of melomys trapped on the last night of four trapping nights in each of two trapping sessions. Despite melomys showing repeatable variation in these behavioural traits, neither boldness nor emergence latency had an effect on detection probability, and we found no evidence that detection probability varied between individuals. This result suggests that any neophobia is experienced and resolved in individuals of this species on a scale of minutes, rather than the hours across which traps are made available each night. Our work demonstrates that personality-caused sampling bias may not be inevitable, even in situations where animals are required to respond to novelty to be detected, such as in baited traps. Heterogeneity in personality does not inevitably lead to heterogeneity in detection probability. Historically, passive traps were assumed a non-biased means of sampling animal populations. Increasingly behavioural ecologists suggest that personality traits, particularly individual boldness, may influence behaviour and, as a consequence, could result in sampling bias. Here, we present a comprehensive example of when animal personality has no effect on detection probability. Despite having distinct personalities, detection probabilities of a native Australian rodent, grassland melomys Melomys burtoni, were not influenced by whether they were ‘shy’ or ‘bold’. We provide evidence that heterogeneity in personality does not inevitably lead to heterogeneity in detection probability. Given that population estimation models typically assume homogeneity in detection probability between individuals, if this is a broad phenomenon, consistently similar results may improve our confidence in this assumption.

The influence of data source and species distribution modelling method on spatial conservation priorities

AbstractAimSpecies distribution models are an important conservation tool; however, performance can vary with factors including data inputs and modelling method. Model outputs are often under‐evaluated for explanatory and predictive capacity. Our aim was to evaluate the capacity of existing data for seven small mammal species to provide useful inferences for management planning.LocationBathurst and Melville (collectively the Tiwi) Islands, Northern Territory, Australia.MethodsWe developed species distribution models (SDMs) with generalized linear models (GLMs) and boosted regression trees (BRTs) using survey data (351 sites) of small mammals, with two sets of environmental predictors: (a) field‐study measurements and (b) available remotely sensed rasters. Predictive capacity of models was evaluated using percentage of deviance explained (%DE) and area under the receiver operating characteristic curve (AUC). We used Marxan to evaluate the influence of different model and data types as input for identifying spatial priorities.ResultsField‐informed SDMs performed well across both modelling methods, with relatively high test AUC values (mean = 0.82, range = 0.64–0.97) and test %DE (mean = 22.5%, range = 3.5%–65.8%). Remotely sensed models performed relatively poorly, with lower test AUC values (mean = 0.7, range = 0.56–0.86) and lower test %DE (mean = 8.9%, range = 0.03%–24.9%). A notable exception was remotely sensed models forMelomys burtoni(AUC = 0.85 & 0.86, %DE = 23.3% & 24.9%, Bathurst and Melville respectively). Marxan site irreplaceability rankings demonstrated low to marginal agreement using field‐informed and remotely sensed inputs (Pearson correlation coefficient = 0.3), and similarly, using GLM and BRT model inputs (0.29).Main conclusionsThe occurrence of small mammals on the Tiwi Islands can be reasonably explained with field‐informed variables, but not with remotely sensed alternatives. Different models lead to different conservation priorities. Our work emphasizes the importance of thoroughly testing SDMs prior to decision‐making.

A novel Australian flying-fox retrovirus shares an evolutionary ancestor with Koala, Gibbon and Melomys gamma-retroviruses.

A novel gamma-retroviral sequence (7912bp), inclusive of both partial 5' and 3' long terminal repeat regions, was identified from the brain of a black flying-fox (Pteropus alecto), Queensland, Australia. The sequence was distinct from other retroviral sequences identified in bats and showed greater identity to Koala, Gibbon ape leukaemia, Melomys burtoni and Woolly monkey retroviruses, forming their own phylogenetic clade. This finding suggests that these retroviruses may have an unknown common ancestor and that further investigation into the diversity of gamma-retroviruses in Australian Pteropus species may elucidate their evolutionary origins.

The effect of wildfire on population dynamics for two native small mammal species in a coastal heathland in Queensland, Australia

The influences of wildfire through population dynamics and life history for two species of small mammals in a south-east Queensland heathland on Bribie Island are presented. Trapping results provided information on breeding, immigration and movement of Melomys burtoni (Grassland melomys) and Rattus lutreolus (Swamp rat). We first investigated and optimized the design of trapping methodology for producing mark-recapture population estimates to compare two adjacent populations, one of which was subjected to an extensive wildfire during the two year study. We consider how well rodents survive wildfire and whether the immediate impacts of fire or altered habitat have the greatest impact on each species. We found the R. lutreolus population was far more influenced by the fire than the M. burtoni population both immediately after the fire and over 18 months of vegetation recovery.

Three new species of the sucking louse genus Hoplopleura (Phthiraptera:Anoplura: Hoplopleuridae) from rodents (Mammalia: Rodentia: Muridae) in northern Australia.

Three new species of the rodent louse genus Hoplopleura (Anoplura: Hoplopleuridae) are described and illustrated from Australia: H. melomydis new species from Melomys burtoni (Muridae: Hydromyini, grassland melomys) and M. capensis (Muridae: Hydromyini, Cape York melomys) from Queensland; H. notomydis new species and H. setosa new species from Notomys alexis (Muridae: Hydromyini, spinifex hopping mouse) from the Northern Territory. These new louse species are the first lice recorded from each of the three host rodent species.

Diel activity patterns of northern Australian small mammals: variation, fixity, and plasticity

The temporal niche has received less attention than the spatial niche in ecological research on free-ranging animals. Most studies that have examined the effect of season on the diel activity patterns of small mammals have been conducted in temperate climates where daily temperatures and day length are important predictors of activity. Extremely seasonal rainfall in northern Australia possibly exerts a strong influence on mammalian activity due to the influx of food resources. Using camera traps set over a 3-year period, we documented the diel activity patterns of 5 species of small mammals co-occurring on Groote Eylandt, in the wet-dry tropics of northern Australia. All species were strictly nocturnal but some responded differently to the effect of season. The northern quoll (Dasyurus hallucatus) displayed a bimodal activity pattern that did not differ between the seasons. The northern brown bandicoot (Isoodon macrourus) displayed bimodal activity in the wet season and unimodal activity in the dry. The more sustained activity of I. macrourus in the dry season may be the result of this species utilizing more cellulose-rich food in times of lower insect abundance, whereas D. hallucatus possibly exhibits lower dietary plasticity. The northern hopping-mouse (Notomys aquilo) was consistently active throughout the night in both seasons. Conversely, the delicate mouse (Pseudomys delicatulus) showed great plasticity in its nocturnal activity which altered significantly depending on both season and habitat. The disparity in activity pattern between these 2 rodents possibly reflects differences in predation risks. The grassland melomys (Melomys burtoni) was recorded only during the dry season in coastal grassland habitat, when its activity peaked sharply after nightfall. Our study highlights the interspecific variation in small mammal activity between the wet and dry seasons in northern Australia, which may be explained by differences in diet, habitat use, and predation risk in these species.

Transspecies Transmission of Gammaretroviruses and the Origin of the Gibbon Ape Leukaemia Virus (GaLV) and the Koala Retrovirus (KoRV)

Transspecies transmission of retroviruses is a frequent event, and the human immunodeficiency virus-1 (HIV-1) is a well-known example. The gibbon ape leukaemia virus (GaLV) and koala retrovirus (KoRV), two gammaretroviruses, are also the result of a transspecies transmission, however from a still unknown host. Related retroviruses have been found in Southeast Asian mice although the sequence similarity was limited. Viruses with a higher sequence homology were isolated from Melomys burtoni, the Australian and Indonesian grassland melomys. However, only the habitats of the koalas and the grassland melomys in Australia are overlapping, indicating that the melomys virus may not be the precursor of the GaLV. Viruses closely related to GaLV/KoRV were also detected in bats. Therefore, given the fact that the habitats of the gibbons in Thailand and the koalas in Australia are far away, and that bats are able to fly over long distances, the hypothesis that retroviruses of bats are the origin of GaLV and KoRV deserves consideration. Analysis of previous transspecies transmissions of retroviruses may help to evaluate the potential of transmission of related retroviruses in the future, e.g., that of porcine endogenous retroviruses (PERVs) during xenotransplantation using pig cells, tissues or organs.

Endogenous Gibbon Ape Leukemia Virus Identified in a Rodent (Melomys burtoni subsp.) from Wallacea (Indonesia).

Gibbon ape leukemia virus (GALV) and koala retrovirus (KoRV) most likely originated from a cross-species transmission of an ancestral retrovirus into koalas and gibbons via one or more intermediate as-yet-unknown hosts. A virus highly similar to GALV has been identified in an Australian native rodent (Melomys burtoni) after extensive screening of Australian wildlife. GALV-like viruses have also been discovered in several Southeast Asian species, although screening has not been extensive and viruses discovered to date are only distantly related to GALV. We therefore screened 26 Southeast Asian rodent species for KoRV- and GALV-like sequences, using hybridization capture and high-throughput sequencing, in the attempt to identify potential GALV and KoRV hosts. Only the individuals belonging to a newly discovered subspecies of Melomys burtoni from Indonesia were positive, yielding an endogenous provirus very closely related to a strain of GALV. The sequence of the critical receptor domain for GALV infection in the Indonesian M. burtoni subsp. was consistent with the susceptibility of the species to GALV infection. The second record of a GALV in M. burtoni provides further evidence that M. burtoni, and potentially other lineages within the widespread subfamily Murinae, may play a role in the spread of GALV-like viruses. The discovery of a GALV in the most western part of the Australo-Papuan distribution of M. burtoni, specifically in a transitional zone between Asia and Australia (Wallacea), may be relevant to the cross-species transmission to gibbons in Southeast Asia and broadens the known distribution of GALVs in wild rodents. Gibbon ape leukemia virus (GALV) and the koala retrovirus (KoRV) are very closely related, yet their hosts neither are closely related nor overlap geographically. Direct cross-species infection between koalas and gibbons is unlikely. Therefore, GALV and KoRV may have arisen via a cross-species transfer from an intermediate host whose range overlaps those of both gibbons and koalas. Using hybridization capture and high-throughput sequencing, we have screened a wide range of rodent candidate hosts from Southeast Asia for KoRV- and GALV-like sequences. Only a Melomys burtoni subspecies from Wallacea (Indonesia) was positive for GALV. We report the genome sequence of this newly identified GALV, the critical domain for infection of its potential cellular receptor, and its phylogenetic relationships with the other previously characterized GALVs. We hypothesize that Melomys burtoni, and potentially related lineages with an Australo-Papuan distribution, may have played a key role in cross-species transmission to other taxa.

Small terrestrial mammals on Doongan Station, in the Northern Kimberley bioregion, Western Australia

There are significant gaps in knowledge of the small terrestrial mammals (<2 kg) in the Northern Kimberley bioregion (NOK). There have been no known extinctions of small mammals in the NOK, despite broad-scale declines being observed across much of northern Australia. The few studies in the NOK have focussed largely on three major national parks and NOK islands and thus may not be fully representative of the region. Mammal surveys were undertaken on Doongan Station, a pastoral property adjacent to these national parks to determine the presence/absence of small mammals. Five species were found to be common (Pseudomys nanus, P. delicatulus, Rattus tunneyi, Zyzomys argurus and Sminthopsis virginiae), two species were detected less frequently (Leggadina lakedownensis and Isoodon macrourus), and four species were scarcely detected (Melomys burtoni, Hydromys chrysogaster, Planigale maculata and Dasyurus hallucatus). Two species were detected only opportunistically outside of the survey effort (Petropseudes dahli and Petaurus breviceps). The trap success was consistently low, with levels in most years being below those regarded as critically low elsewhere in northern Australia.

Discovery of a novel retrovirus sequence in an Australian native rodent (Melomys burtoni): a putative link between gibbon ape leukemia virus and koala retrovirus.

Gibbon ape leukaemia virus (GALV) and koala retrovirus (KoRV) share a remarkably close sequence identity despite the fact that they occur in distantly related mammals on different continents. It has previously been suggested that infection of their respective hosts may have occurred as a result of a species jump from another, as yet unidentified vertebrate host. To investigate possible sources of these retroviruses in the Australian context, DNA samples were obtained from 42 vertebrate species and screened using PCR in order to detect proviral sequences closely related to KoRV and GALV. Four proviral partial sequences totalling 2880 bases which share a strong similarity with KoRV and GALV were detected in DNA from a native Australian rodent, the grassland melomys, Melomys burtoni. We have designated this novel gammaretrovirus Melomys burtoni retrovirus (MbRV). The concatenated nucleotide sequence of MbRV shares 93% identity with the corresponding sequence from GALV-SEATO and 83% identity with KoRV. The geographic ranges of the grassland melomys and of the koala partially overlap. Thus a species jump by MbRV from melomys to koalas is conceivable. However the genus Melomys does not occur in mainland South East Asia and so it appears most likely that another as yet unidentified host was the source of GALV.

The origins and ecological impact of koala retrovirus

The genome of koala retrovirus (KoRV) has striking similarity to the gibbon ape leukemia virus (GALV) genome, suggesting the two viruses may share a common ancestor. Screening of DNA from a range of potential hosts of this putative ancestor virus revealed retroviral sequence from a grassland melomys (Melomys burtoni) that was closely related to sequence of both KoRV and GALV. This novel virus has been named Melomys burtoni retrovirus (MbRV). As grassland melomys and koalas share habitat, it is possible that there has been cross-species transmission of virus in the past. A lthough a causative relationship between KoRV infection and disease in koalas is yet to be confirmed, koala populations with a high prevalence of KoRV infection have a higher incidence of diseases characteristic of retroviruses (cancer and immunosuppression) than populations with low KoRV- prevalence. Not all KoRV-infected koalas develop clinical disease. This variation in disease expression may result from differences in proviral (DNA) insertion sites among koalas, genetic variability of KoRV in different individuals or from variation in host genetics.

Predation on invasive cane toads (Rhinella marina) by native Australian rodents

The success of an invasive species can be reduced by biotic resistance from the native fauna. For example, an invader that is eaten by native predators is less likely to thrive than one that is invulnerable. The ability of invasive cane toads (Rhinella marina) to spread through Australia has been attributed to the toad’s potent defensive chemicals that can be fatal if ingested by native snakes, lizards, marsupials and crocodiles. However, several taxa of native insects and birds are resistant to cane toad toxins. If native rodents are also capable of eating toads (as suggested by anecdotal reports), these large, abundant and voracious predators might reduce toad numbers. Our field observations and laboratory trials confirm that native rodents (Melomys burtoni, Rattus colletti and Rattus tunneyi) readily kill and consume cane toads (especially small toads), and are not overtly affected by toad toxins. Captive rodents did not decrease their consumption of toads over successive trials, and ate toads even when alternative food types were available. In combination with anecdotal reports, our data suggest that rodents (both native and invasive) are predators of cane toads in Australia. Despite concerns about the decline of rodents following the invasion of toads, our data suggest that the species we studied are not threatened by toads as toxic prey, and no specific conservation actions are required to ensure their persistence.

Thwarting plague and pestilence in the Australian sugar industry: Crop protection capacity and resilience built by agricultural extension

This paper investigates how Australian sugar industry extension services over the last decade have overcome historical pest management challenges in sugarcane (Saccharum spp.). The industry has done this by building increased capacity amongst its extension agents and farmers. This paper considers how coordinated extension efforts have reduced production losses from its two principal pests: greyback canegrub –Dermolepida albohirtum (Waterhouse), and rodents (i.e., Rattus sordidus and Melomys burtoni). It details the complexity of the respective pest management issues and the efficacy of industry efforts in resolving outbreak situations in the early 2000s. The paper then investigates how combined research, development and extension efforts have been able to mitigate risk of similar outbreaks over the last decade. These RD&E efforts have delivered IPM packages that are practical, defined, and ready for on-farm use. They have delivered sustained reductions in pest damage and an increase in knowledge and skills amongst extension agents and growers. Overall, industry is more confident, skilled and pro-active in the management of rats and canegrubs than in decades past. Consequently, the Australian sugar industry is a more resilient entity as a function of these extension initiatives. The strategies described here provide a model for building capacity and resilience in the sugar and other industries when confronted with multi-faceted challenges related to pest biology and behaviour, availability of inputs for production, economic forces and environmental considerations.

Population dynamics, diet and pest status of the grassland melomys (Melomys burtoni) in northern Queensland sugarcane crops

Context In far-northern Queensland, Melomys burtoni and M. cervinipes occur within sugarcane crops and adjacent habitats and are potentially damaging to sugarcane. Aims To examine the population dynamics and diet of Melomys spp. within sugarcane crops so that, in conjunction with cane-stalk damage assessments, their pest status could be determined and information provided relevant to the development of sustainable pest-management tools. Methods Eight sites within sugarcane fields, four adjacent to grassland and four adjacent to closed forest, were established around Tully in far-northern Queensland. We examined demographic characteristics of all rodents (the two Melomys spp. and Rattus sordidus) within the crops by capture–release studies. Snap-trapping and dissection studies, along with weed-biomass surveys, were conducted for diet analysis, whereas damaged stalk counts were undertaken to understand the damage process. Fieldwork commenced within a fully developed crop, then continued through the annual harvest period and all subsequent crop growth stages to the next harvest. Sampling was undertaken monthly from February 2005 to April 2006. Key results Melomys cervinipes was rarely caught in sugarcane and should not be regarded as a pest. In contrast, M. burtoni feeds on sugarcane and was responsible for damage to ~6% of stalks. In sites adjacent to closed forest, R. sordidus was found in higher numbers than was M. burtoni in Crop stages 2–4. However, at sites adjacent to grassland, numbers of M. burtoni increased in Crop stage 4, and before crop harvest, M. burtoni was found in higher numbers than was R. sordidus. M. burtoni colonised sugarcane at later stages of crop development than did R. sordidus. Although the level of M. burtoni reproduction was lower than that of R. sordidus, the highest proportion of pregnant M. burtoni individuals occurred during the later stages of crop development, corresponding directly with the highest proportion of juvenile recruitment. Conclusions Of the two Melomys species found in northern Queensland sugarcane crops, only M. burtoni should be regarded as a pest. This rodent breeds and feeds within the crop, primarily after canopy closure. M. burtoni captures were roughly equivalent irrespective of adjacent habitat type, whereas R. sordidus, the traditionally recognised major pest of sugarcane crops, was found in significantly higher numbers in sugarcane adjacent to closed forest. Implications The integrated pest-management (IPM) strategy developed for R. sordidus is centred on the early stages of crop development and includes population monitoring, in-crop weed control, harbourage management and strategic use of permitted rodenticides. The late colonisation and lower breeding potential of M. burtoni mean that the IPM strategy for R. sordidus will not be directly transferable to M. burtoni.