The elaborate, socially transmitted songs of songbirds are among the clearest examples of animal culture, and these vocalizations play key roles in reproduction and competition for resources. Failing to account for songbird vocal cultures in conservation management actions including translocation can - inadvertently - deplete cultural diversity and may negatively impact the viability of populations. However, data on vocalizations are unavailable for most cryptic and threatened songbird species, inhibiting the development of management strategies that account for and preserve important vocal cultures. We provide the first study of song for the endangered Eastern Bristlebird Dasyornis brachypterus. The Eastern Bristlebird is confined to three small, disjunct regions along Australia's east coast, and has recently undergone an ambitious three-part conservation translocation programme to minimize its risk of extinction. We recorded Eastern Bristlebird vocalizations during the breeding season preceding translocation, within the most stable and genetically diverse population, on Bherwerre Peninsula, in Jervis Bay. We quantified the species singing behaviour and song structures, and assessed geographical variation in song-sharing. Eastern Bristlebirds sang discrete 1.0-s 'A-songs', each comprising three to seven unique elements, within structured song bouts. Individuals had an average repertoire size of 12 different A-song types, and a total of 66 A-song types were documented across the Bherwerre Peninsula population. Song-type sharing between individuals declined with increasing geographical distance. We found evidence of dialect separation between geographically distinct groups of individuals, consistent with the spatial extent of the species' preferred coastal heathland habitat at Bherwerre Peninsula. Permuted discriminant function analysis (pDFA) showed that A-songs had a consistent internal structure, although the pDFA was better at classifying the structurally simple 'introductory' elements of the A-songs, than the structurally variable 'body' elements. Our study provides new insights into Eastern Bristlebird song culture and represents the first step towards integrating bioacoustics research into conservation management, including current and future translocations, in the hope of developing new strategies to preserve cultural diversity alongside genetic diversity in this endangered songbird species.

Wildlife are implicated in the dissemination of antimicrobial resistance, but their roles as hosts for Escherichia coli that pose a threat to human and animal health is limited. Gulls (family Laridae) in particular, are known to carry diverse lineages of multiple-antibiotic resistant E. coli, including extra-intestinal pathogenic E. coli (ExPEC). Whole genome sequencing of 431 E. coli isolates from 69 healthy Australian silver gulls (Chroicocephalus novaehollandiae) sampled during the 2019 breeding season, and without antibiotic selection, was undertaken to assess carriage in an urban wildlife population. Phylogenetic analysis and genotyping resolved 123 sequence types (STs) representing most phylogroups, and identified diverse ExPEC, including an expansive phylogroup B2 cluster comprising 103 isolates (24 %; 31 STs). Analysis of the mobilome identified: i) widespread carriage of the Yersinia High Pathogenicity Island (HPI), a key ExPEC virulence determinant; ii) broad distribution of two novel phage elements, each carrying sitABCD and iii) carriage of the transmissible locus of stress tolerance (tLST), an element linked to sanitation resistance. Of the 169 HPI carrying isolates, 49 (48 %) represented diverse B2 isolates hosting FII-64 ColV-like plasmids that lacked iutABC and sitABC operons typical of ColV plasmids, but carried the serine protease autotransporter gene, sha. Diverse E. coli also carried archetypal ColV plasmids (52 isolates; 12 %). Clusters of closely related E. coli (<50 SNVs) from ST58, ST457 and ST746, sourced from healthy gulls, humans, and companion animals, were frequently identified. In summary, anthropogenically impacted gulls host an expansive E. coli population, including: i) putative ExPEC that carry ColV virulence gene cargo (101 isolates; 23.4 %) and HPI (169 isolates; 39 %); ii) atypical enteropathogenic E. coli (EPEC) (17 isolates; 3.9 %), and iii) E. coli that carry the tLST (20 isolates; 4.6 %). Gulls play an important role in the evolution and transmission of E. coli that impact human health.

Antimicrobial resistance (AMR) is a major public health concern, and environmental bacteria have been recognized as important reservoirs of antimicrobial resistance genes (ARGs). Citrobacter, a common environmental bacterium and opportunistic pathogen in humans and other animals, has been largely understudied interms of its diversity and AMR potential. Whole-genome (short-read) sequencing on a total of 77 Citrobacter isolates obtained from Australian silver gull (Chroicocephalus novaehollandiae) (n = 17) and influent wastewater samples (n = 60) was performed, revealing a diverse Citrobacter population, with seven different species and 33 sequence types, 17 of which were novel. From silver gull using non-selective media we isolated a broader range of species with little to no mobilised ARG carriage. Wastewater isolates (selected using Carbapenem-Resistant Enterobacterales (CRE) selective media) carried a heavy burden of ARGs (up to 21 ARGs, conferring resistance to nine classes of antibiotics), with several novel multidrug-resistant (MDR) lineages identified, including C. braakii ST1110, which carried ARGs conferring resistance to eight to nine classes of antibiotics, and C. freundii ST1105, which carried two carbapenemase genes, blaIMP-4 in class 1 integron structure, and blaKPC-2. Additionally, we identified an MDR C. portucalensis isolate carrying blaNDM-1, blaSHV-12, and mcr-9. We identified IncC, IncM2, and IncP6 plasmids as the likely vectors for many of the critically important mobilised ARGs. Phylogenetic analyses were performed to assess any epidemiological linkages between isolation sources, demonstrating low relatedness across sources beyond the ST level. However, these analyses did reveal some closer relationships between strains from disparate wastewater sources despite their collection some 13,000 km apart. These findings support the need for future surveillance of Citrobacter populations in wastewater and wildlife populations to monitor for potential opportunistic human pathogens.

The relationship between sublethal pesticide exposure and oxidative stress in an ecologically relevant field setting is relatively unknown for reptiles. Oxidative stress is a multi-faceted concept that dictates key survival and fitness parameters in any organism. Fipronil and fenitrothion are two pesticides widely used globally for agricultural pest management. Using a field-based, BACI designed experiment we investigated the impact of sublethal pesticide exposure on oxidative stress biomarkers protein carbonyl and DNA damage (8-OHdG), in an arid-zone lizard species, Pogona vitticeps. A single ecologically relevant dose of pesticide was applied via oral gavage to treatment animals. Lizard condition, activity measures, and blood biomarkers were measured at relevant sampling intervals. Cholinesterase (ChE) and acetylcholinesterase (AChE) enzymatic biomarkers were measured in response to fenitrothion, and fipronil blood residues were measured for fipronil-treated lizards. Results suggested no significant treatment effect of either pesticide on parameters measured, however, 8-OHdG levels decreased by ≥ 45% for both pesticide treatment groups and not controls. Protein carbonyl levels showed a high degree of individual variation that proved more influential than pesticide exposure. Building our understanding of the macromolecular impacts of sublethal pesticide exposure on wild lizard populations is an integral step in addressing the current gap in literature and management practices. Our study has also highlighted the complex nature of studying oxidative stress in the field and the sheer necessity of future study.

ABSTRACT Exposure of songbirds to organophosphorous pesticides has been shown to affect a range of behavioural characteristics including singing, displaying and flying that consequently can have significant impacts on the viability of free-living individuals and populations. In the current study, display flights of male Brown Songlarks (Cincloramphus cruralis Vigors and Horsfield 1827) before and after the application of fenitrothion (O,O-dimethyl-O-[3-methyl-4-nitrophenyl]-phosphorothioate) during locust spray operations around Conargo, south western New South Wales, were monitored incidentally for number, duration and the presence of song during flight. The duration of display flights undertaken by male C. cruralis showed a statistically significant increase after exposure to fenitrothion (t0.05, 398 = 1.97; p = 0.0085, analysed using log10 transformed flight duration data), despite the mean number of flights undertaken decreasing from 5.7 pre-spray to 4.7 post-spray during 10 min survey periods. The proportion of display flights in which the male was calling, however, did not differ between pesticide-exposed and unexposed male C. cruralis (χ2(0.05, 1) = 0.323; p = 0.570). To better understand the impacts of pesticide exposure on C. cruralis behaviour and ecology, the observations presented here require further study and validation with the addition of other variables such as territory mapping, assessment of reproductive success and the quantification of enzymatic biomarkers indicative of exposure to organophosphorous insecticides, undertaken concomitantly.

ABSTRACT The use of chemical pesticides to manage locust populations in natural ecosystems is likely to impact non-target arthropods and their predators. However, the relative effects of different locust control applications on Australian birds are unknown. Aerial applications of fipronil and fenitrothion are examples of two pesticides used in locust control in semiarid Australia. To test the relative impacts of pesticides on non-target fauna, pesticides were applied to replicate sites using aerial ultra-low-volume application methods. The body condition and biomarkers of pesticide exposure in resident white-winged fairy wrens (Malurus leucopterus leuconotus) at treatment and control sites were measured for two weeks before and after treatments. No measures suggested negative impacts of pesticide applications. However, birds monitored at treatment sites gained mass, possibly due to indirect impacts of pesticides on bird feeding patterns or the availability or behaviour of insect prey. Bird mass measures remained high at fipronil sites, whereas the mass of birds at fenitrothion sites returned to baseline levels within one week. As this study was conducted during dry conditions, when locust plagues are less likely, future insecticide research should also consider the availability of insect prey, its effect on insectivore feeding behaviour and the interaction of rainfall events.

Abstract Emergency conservation interventions will be increasingly necessary to prevent extinctions or severe population bottlenecks as extreme events become more frequent. We detail the emergency extraction of the endangered Eastern Bristlebird (Dasyornis brachpterus) during the unprecedented 2019–2020 Australian Black Summer bushfires, an intervention that led to the rapid establishment of a temporary ex situ insurance population sourced from an area under immediate threat from bushfire (Croajingolong National Park, Victoria). The intervention was triggered, coordinated, and implemented within a 4‐week period, with re‐release to the wild within 2 months. We present this case study within a framework for emergency conservation interventions, based on the emergency management phases of preparation, response, and recovery, with the addition of an evaluation phase. The preparation phase involved compiling existing knowledge and capacity to facilitate the operation. The response phase consisted of (a) initiation and planning of the intervention (coordination) and (b) implementation, that is, the translocation of 15 birds from an area under threat of bushfire to a captive institution (>500 km). The recovery phase saw the insurance population re‐released to unburnt habitat after the bushfire had ceased. The evaluation phase incorporated lessons learnt from the other three phases as part of an adaptive management approach. We reflect on the Eastern Bristlebird emergency conservation intervention to explore how we can better prepare for, respond to, and recover from the large range of emergencies faced by biodiversity around the world.

Context Quantifying the space use and movement patterns of animals is important to understand other aspects of a species ecology, such as habitat use and social systems. However, basic data on space use and movement patterns, and how they are influenced by biotic or abiotic factors, are lacking for many species. Aims We identified the space use and movement patterns of the central bearded dragon (Pogona vitticeps), and assessed how external factors (environmental conditions) and internal factors (sex and morphology) shape these patterns. Methods We tracked 36 P. vitticeps individuals over three seasons from 2017 to 2018. Animals carried tags with a Global Positioning Systems (GPS) device to collect spatial data and an accelerometer to collect movement data in far western New South Wales, Australia. Measurements of body morphology were taken for each individual and ambient temperatures were recorded. Space use was analysed by calculating minimum convex polygons (MCPs) and kernel density estimates (KDEs) using the spatial data. Movement data were analysed to determine whether dragons had moved during 10-min periods. Results Twenty-three out of 36 individuals held defined activity areas. Males with wider tails were most likely to be floaters (i.e. not restricted to specific areas). Evidence of floater behaviour was shown by 45% of females and 20% of males, though both sexes often roamed over distances greater than 1 km. Air temperatures strongly influenced movement rates in both sexes. Movement rate was significantly higher for males than females during late-spring, but not mid-summer, and was inversely related to head sizes and body mass during mid-summer. Interestingly, although there was no correlation observed between daily movement rates and size of MCPs calculated, the movement rates of residents were significantly different from floaters for each season. Conclusions These results confirm that wild P. vitticeps movement patterns are driven by temperature, though space-use patterns vary from previously studied agamids, with high rates of nomadism, possibly due to drought conditions. Individuals varied widely in their space-use tactics, which seem unrelated to size, a potential proxy for social status or age. Implications Our study provides baseline information on a common arid zone agamid that is lacking research in the wild. More complex studies on the ecology of P. vitticeps can build on the findings of this study.

The use of chemical pesticides to manage locust populations in natural ecosystems is likely to impact non-target arthropods and their predators. However, the relative effects of different locust control applications on Australian birds are unknown. Aerial applications of fipronil and fenitrothion are examples of two pesticides used in locust control in semiarid Australia. To test the relative impacts of pesticides on non-target fauna, pesticides were applied to replicate sites using aerial ultra-low-volume application methods. The body condition and biomarkers of pesticide exposure in resident white-winged fairy wrens (Malurus leucopterus leuconotus) at treatment and control sites were measured for two weeks before and after treatments. No measures suggested negative impacts of pesticide applications. However, birds monitored at treatment sites gained mass, possibly due to indirect impacts of pesticides on bird feeding patterns or the availability or behaviour of insect prey. Bird mass measures remained high at fipronil sites, whereas the mass of birds at fenitrothion sites returned to baseline levels within one week. As this study was conducted during dry conditions, when locust plagues are less likely, future insecticide research should also consider the availability of insect prey, its effect on insectivore feeding behaviour and the interaction of rainfall events.

Assessment of non-target impacts of pesticides used widely in agriculture and pest management rarely considers reptiles. Despite their integral role in all ecosystems, particularly arid ecosystems, reptiles are not included in risk assessments. Two pesticides used in agricultural pest management are fipronil and fenitrothion. Here, we used a field-based BACI design experiment in semi-arid Australia to investigate the impact of these pesticides on basic physiological and behavioural parameters of a common arid-zone lizard species, Pogona vitticeps. Fipronil and fenitrothion were applied at ecologically relevant doses via oral gavage. Before and after dosing, blood, physical activity and body condition parameters were assessed. We found that temperature significantly influenced lizard activity in the morning period of movement; however, fipronil-treated individuals moved at least 49% less than fenitrothion-treated and control lizards from 7 days after dosing through to the end of the experiment. Physiological measures did not change significantly before or after exposure to both pesticides; however, other indicators showed evidence of exposure, which remained for the entirety of our monitoring period. On average, cholinesterase inhibition was still >30% compared with control lizards at the end of 4 weeks, and fipronil sulfone blood residues remained at 0.219 μg/ml. Our study provides novel insights into the impacts that common pesticides have on widespread lizard species. We show that an ecologically relevant low dose of fipronil alters the behaviour of P. vitticeps, which has the potential to impact longer-term survivability. Persistence of both pesticides in the blood of all treatment lizards throughout the experiment indicates they are unable to clear these toxins within a month of being exposed. This may be significant for compounding exposure and latent toxicity. These findings highlight the susceptibility that reptiles have to a selection of common pesticides and the inherent need for higher prominence in wildlife ecotoxicological research.

The ability to produce large numbers of pesticide-exposed insects (e.g. crickets) is important for feeding studies into the effects of pesticides on key predatory species. House crickets (Acheta domesticus L. 1758) were submersed in serial dilutions of the pesticides, fenitrothion and fipronil, used for the control of locusts in Australia, and then rapidly frozen for residue analysis. Good correlations were found between increasing concentrations of serial pesticide dilutions and the resultant residual concentrations of the parent compounds in crickets, with R2 values of 0.949 (fenitrothion) and 0.946 (fipronil). R2 values for the much less abundant fipronil metabolites were lower 0.858 (sulfone), 0.368 (desulfinyl) and 0.785 (sulfide). This method enables insecticide exposure mimicking the field conditions to be assessed, and can be done immediately prior to an experiment. This ensures locusts remain alive when introduced to the feeding chambers, and enables multiple prey items to be dosed with a known pesticide burden.

Defining environmental reservoirs hosting mobile genetic elements that shuttle critically important antibiotic resistance genes is key to understanding antimicrobial resistance (AMR) from a One Health perspective. Gulls frequent public amenities, parklands, and sewage and other waste disposal sites and carry drug-resistant Escherichia coli.

Background Quantifying the space-use and movement patterns of animals is critical to understanding habitat use and social systems. Little is known of the finer details of lizard movement biology, due to the limitations of observational studies. Advancements in technology has greatly improved our ability to study animal space-use and movement, though new technology has rarely been used to quantify finer-scale lizard movements and space-use. Using Global Positioning Systems (GPS) tags and accelerometers we tracked 36 central bearded dragon ( Pogona vitticeps ) individuals over three seasons, with the aim to describe space-use and movement patterns and to determine how these patterns differ due to individual traits and environmental drivers.Results Home ranges were held by 23 out of 36 individuals and wider tailed males were more likely to be floaters (no evidence of a home range). Evidence of floater behaviour was shown by 45% of females and only 20% of males, though both sexes often roamed over distances greater than 1 km. No significant relationships were observed among home range parameters and the individual traits measured. Home range overlap occurred between both neighbouring males and females, and core areas were not exclusive. Air temperatures strongly influenced movement in both sexes. Movement was significantly higher for males than females during late-spring, but not mid-summer, and was inversely related to head sizes and body mass during mid-summer. Interestingly, no correlation was observed between daily movement rates and home range measures. However, the movement rates of home range holders were significantly different from floaters for each season.Conclusions These results confirm that wild P. vitticeps movement patterns are driven by temperature, though space-use patterns vary from previously studied agamids, with high rates of nomadism, possibly due to drought conditions and high intrasexual home range overlap. Individuals varied widely in their space-use tactics, which seem unrelated to size, a potential proxy for social status or age. Our detailed data highlights the utility of accelerometers and GPS tracking devices in the study of lizard ecology.

Large rain events drive dramatic resource pulses and the complex pulse-reserve dynamics of arid ecosystems change between high-rain years and drought. However, arid-zone animal responses to short-term changes in climate are unknown, particularly smaller rain events that briefly interrupt longer-term drought. Using arthropods as model animals, we determined the effects of a small rain event on arthropod abundance in western New South Wales, Australia during a longer-term shift toward drought. Arthropod abundance decreased over 2 yr, but captures of 10 out of 15 ordinal taxa increased dramatically after the small rain event (<40 mm). The magnitude of increases ranged from 10.4 million% (collembolans) to 81% (spiders). After 3 months, most taxa returned to prerain abundance. However, small soil-dwelling beetles, mites, spiders, and collembolans retained high abundances despite the onset of winter temperatures and lack of subsequent rain. As predicted by pulse-reserve models, most arid-zone arthropod populations declined during drought. However, small rain events may play a role in buffering some taxa from declines during longer-term drought or other xenobiotic influences. We outline the framework for a new model of animal responses to environmental conditions in the arid zone, as some species clearly benefit from rain inputs that do not dramatically influence primary productivity.

Urban waterbirds are considered both serious pests and inspiring wildlife. Ibis and gulls are often vilified due to their dirty appearance and disruption of outdoor activities, while ducks are affectionately fed in parks. However, all waterbirds are potential reservoirs of zoonotic pathogens. In Sydney (Australia), we documented the relative prevalence of arbovirus exposure and Salmonella shedding in 72 Australian White Ibis (Threskiornis moluccus) at 2 urban sites in 2003 during a management cull and in 2015 as a response to increased public interest. We sampled during a period of peak human arbovirus and Salmonella infection risk in late summer and early autumn. In 2015, antibodies for the endemic West Nile virus Kunjin strain (WNVKUN) were detected in one bird. While not indicative of immediate public health risk, this highlights that an animal with a history of exposure was present or moved into a region not previously known to have endemic WNVKUN activity. However, the movement patterns of this individual and WNVKUN host competency of this species are unknown. An absence of other antibody responses suggests that ibis are not important viral reservoirs or flaviviruses are not widespread in Sydney. Assays failed to detect Salmonella in 2015, but 25% of individuals were positive in 2003. Further monitoring of the arguable health hazard represented by urban T. moluccus will facilitate informed decisions and solutions to urban bird and wetland management challenges.

Restoration practitioners commonly use plantings of young seedlings to restore endangered forest communities impacted by anthropogenic disturbance, such as weed invasion and deforestation. Forest recovery may be significantly hampered by browsing pressure from herbivores, and practitioners use a variety of plant guard techniques to reduce the negative impacts of browsing on plant establishment and facilitate ecosystem regeneration. However, there is limited knowledge of which herbivore exclusion methods are most effective in protecting growing seedlings from attack and whether such benefits vary amongst different resident plant species. We compared levels of herbivore damage for 54 native rainforest tree and shrub species amongst four guard treatments that are commonly deployed by restoration practitioners to protect revegetated seedlings from attack by non-native rusa deer (Cervus timorensis) and native vertebrate herbivores during their establishment: (1) small corrugated plastic guards; (2) tall wire guards that protect single seedlings from attack; (3) small fenced exclusion plots that protect multiple revegetated seedlings as well as passively regenerating plants simultaneously; (4) unguarded plants. We also evaluated the effects of exclusion plots on the richness and composition of passively regenerating native vegetation in addition to the growth of actively revegetated seedlings through reduced herbivore activity. Herbivore activity was briefly surveyed using camera traps, and swamp wallabies (Wallabia bicolor) were found to be more active at the site than non-native rusa deer. All guard treatments significantly reduced browsing damage compared with unguarded plants, but corrugated plastic guards were less effective than wire guards and fenced exclusion plots. The fenced exclusion plots had the additional benefit of facilitating the passive regeneration of native plant species that may be cost prohibitive to regeneration otherwise. We also found that species varied in susceptibility to browsing, with eight species suffering high browse damage and five species low damage when unguarded. These findings highlight the potential for exclusion fences to provide more efficient and effective protection of browser preferred plants in the context of rainforest restoration.

Interspecific aggression by the noisy miner (Manorina melanocephala), a highly despotic species, is homogenizing woodland avifaunas across eastern Australia. Although a native species, the noisy miner's aggressive exclusion of small birds is a Key Threatening Process under national law. Large-scale removal of noisy miners has been proposed as a management response to this threat following increases in miner presence due to anthropogenic land use practices. We tested this proposal by experimentally removing noisy miners from eucalypt woodland remnants (16-49ha), assigned randomly as control (n=12) or treatment (miner removal) sites (n=12). Standardized bird surveys were conducted before and after removal, and generalized linear mixed models were used to investigate the effect of miner removal on bird assemblage metrics. Despite removing 3552 noisy miners in three sessions of systematic shooting, densities of noisy miners remained similarly high in treatment and control sites, even just 14days after their removal. However, there was evidence of an increase in richness and abundance of small birds in treatment sites compared to controlsan effect we only expected to see if noisy miner densities were drastically reduced. We suggest that miner removal may have reduced the ability of the recolonizing miners to aggressively exclude small birds, even without substantially reducing miner densities, due to the breakdown of social structures that are central to the species' despotic behaviour. However, this effect on small birds is unlikely to persist in the long term. Synthesis and applications: Despite evidence from other studies that direct removal of noisy miners can result in rapid and sustained conservation benefit for bird communities at small scales, our findings cast doubt on the potential to scale-up this management approach. The circumstances under which direct control of noisy miners can be achieved remain unresolved.

Declines in population size can compromise the viability of populations by reducing the effective population size (Ne), which may result in loss of genetic diversity and inbreeding. Temporal population genetic data can be a powerful tool for testing the presence and severity of reductions in Ne. The Gouldian finch (Erythrura gouldiae) is a flagship for conservation of Australian monsoonal savanna species. This species underwent severe population declines in the twentieth century due to land use changes associated with European colonization. Microsatellite and mitochondrial genetic data from Gouldian finch samples sourced from natural history collections prior to land use changes were compared with contemporary samples to estimate the severity of decline in effective population size and to detect changes in gene flow. These data show that Gouldian finch decline was not as severe as some sources suggest, and that population genetic connectivity has not changed following land use changes in the twentieth century. Multiple estimators of current Ne using genetic data from consecutive years suggest the Gouldian finch Ne is likely between a few hundred and a few thousand individuals, with some estimates within the range considered of conservation concern. This work has identified the need to genetically characterize populations in Queensland, and to understand critical demographic parameters (e.g. lifespan) in the Gouldian finch. Understanding these factors is vital to further improve genetic estimates of population size, key to the formation of appropriate conservation management of this species.

Like the author, I never assumed that birds were stupid. For those that admire bird beauty and behaviour, Jennifer Ackerman’s quest to understand the genius of birds is a fantastic expedition into ...

Litter and microbes are key drivers of nutrient cycles, particularly in arid ecosystems where decomposition rates are low. Locust control in arid regions represents a potentially important hazard to microbes, because local taxa are unlikely to have adapted to pesticide exposure and operations often occur during times of high microbial activity. We monitored the response of aboveground litter decomposition and soil bacteria functional diversity to aerial applications of fipronil (a chemical pesticide) barrier treatments and Metarhizium acridum (a fungal biopesticide) blanket treatments. Decomposition was monitored over 2 years (before and after treatments) using a replicated litter-bag experiment, whereas changes in bacteria functional diversity were measured over 1 month. Analysis of litter mass loss indicated there were no pesticide treatment effects relative to control. Less litter decomposed in small than large mesh bags, and less litter decomposed during the second year of the study. Litter had higher mean nitrogen (N) and carbon (C), and a lower C:N ratio, during the first year of the study. In contrast, within-treatment site analysis revealed a significant increase in litter mass remaining in bags at M. acridum-treated subsites. However, these values were only 4% different from control sites, suggesting that the effect detected may not be biologically significant. There appeared to be no pesticide treatment effect on bacterial community functional diversity and no significant temporal variation. The lack of large-scale pesticide treatment effects suggests that arid zone fungi and bacteria are resilient to such disturbances. Differences in decomposition was explained by differences in the activity of arthropods and in the shade provided by the two mesh sizes, and an annual decline could be attributed to lower litter C and N content and lower annual rainfall in Year 2. Results show the temporal variation possible in decomposition and microbe community measures in arid systems.