Wayne A. Robinson’s research while affiliated with Charles Sturt University and other places

Many species have adapted successfully to traditionally cultivated agricultural environments but, as production systems are intensified, this adaptation is reaching its limits. Conflicting facets of sustainability compound the problem. Here we describe how reductions in the use of water in rice fields is compromising the persistence of the largest known breeding population of the Australasian Bittern (Botaurus poiciloptilus), a globally endangered waterbird. In fields with traditional, early permanent water, bitterns began nesting around 77 days after inundation, with 65% of nests having sufficient time for all chicks to fledge before harvest. Our breeding success model showed that all nests could potentially be successful if permanent water was applied by early November, with a ponding period - the phase when fields are flooded - of at least 149 days. The modelling suggests that successful bittern breeding was unlikely where rice was grown using new water-saving methods - drill-sown and delayed permanent water - because the ponding period is too short. These methods have become the rice industry standard in Australia, rising from 34% of fields in 2014 to 91% in 2020. While this saved 1.5-4.5 megalitres/ha per year, it has undermined the habitat value of these agricultural wetlands. 'Bittern-friendly' rice growing incentives could encourage timely nesting and maximise breeding success. Early and sufficient ponding can be complemented by establishing adjacent wetland habitat refuges, maintaining grassy banks, and creating dedicated patches to fast-track nesting. Increasing water-use efficiency in agro-ecosystems is widely touted as being beneficial to the environment, but our research demonstrates the urgent need to manage trade-offs with biodiversity conservation.

Barley grass (Hordeum murinum subsp. glaucum.) is an annual weed associated with grain revenue loss and sheep carcass damage in southern Australia. Increasing herbicide resistance led to a recent investigation into effective integrated weed management strategies for barley grass in southern Australia. Field studies in Wagga Wagga, New South Wales (NSW) during 2016 and 2017 examined the effect of post-emergent herbicide applications and strategic defoliation by mowing on barley grass survival and seed production in a mixed legume pasture. Statistically significant differences between herbicide-only treatments in both years showed propaquizafop to be more than 98% effective in reducing barley grass survival and seed production. Paraquat was not effective in controlling barley grass (58% efficacy), but led to a 36% and 63.5% decrease in clover and other weed biomass, respectively, after 12 months and increased lucerne biomass by over three-fold after 24 months. A single repeated mowing treatment resulted in a 46% decline in barley grass seedling emergence after 12 months and, when integrated with herbicide applications, reduced other weed biomass after 24 months by 95%. Resistance to acetyl-CoA carboxylase (ACCase)-inhibiting herbicides observed in local barley grass populations led to additional and more focused investigation comparing the efficacy of other pre- and post-emergent herbicides for barley grass management in legume pastures. Haloxyfop-R + simazine or paraquat, applied at early tillering stage, were most efficacious in reducing barley grass survival and fecundity. Impact of defoliation timing and frequency on barley grass seedlings was also evaluated at various population densities, highlighting the efficacy of repeated post-inflorescence defoliations in reducing plant survival and seed production. Results highlight the importance of optimal environmental conditions and application timing in achieving efficacious control of barley grass and improving pasture growth and biomass accumulation.

Wasmannia auropunctata (Roger) (Hymenoptera: Formicidae) is among the world’s worst invasive species, and there is an increasing need for effective control methods for this species. Existing chemical treatments and baits used in managing other invasive ant species may not be as effective for managing W. auropunctata. Development of effective ant control treatments and baits depends on laboratory experiments to test the potential efficacy of a large number of products and control methods prior to implementation of large-scale field studies. However, anecdotal evidence suggests that laboratory- raised W. auropunctata may respond differently than their wild counterparts to bait types, and if this is the case, laboratory trials may not accurately predict results under field conditions. Here we report on experimental research investigating whether ant colonies raised in laboratories, and those in the field, show different patterns of recruitment to non-toxic baits. Laboratory and wild colony recruitment to non-toxic Hawaii Ant Lab gel bait, pureed tuna, and 50% gelled sucrose solution was measured via multi-choice and no-choice field recruitment studies. Secondly, we discuss experiments testing whether the bait preference of laboratory-raised W. auropuncata varies with their base diet. We tested 4 base diets: (1) lipid rich, (2) protein rich, (3) carbohydrate rich, and (4) a “complete” diet with lipid, protein, and carbohydrates offered as a buffet. Overall, we found that laboratory colonies differed from wild W. auropunctata in their foraging behaviors in no-choice and multi choice experiments, particularly in their levels of recruitment to the Hawaii Ant Lab gel bait. This contrast indicates that experimental trials may give misleading indications of potential outcomes of field trials. Further research is needed on optimal laboratory diets for laboratory-reared ant colonies. However, our results suggest that behavioral differences may be mitigated if colonies are maintained on a nutritionally limited diet while conducting laboratory experiments.

The seeds of most Australian acacias have pronounced physical dormancy (PY). While fire and hot water (HW) treatments cause the lens to ‘pop’ almost instantaneously, for many Acacia species the increase in germination percentage can be gradual. If PY is broken instantly by HW treatment, why is germination often an extended process? Control and HW treatments were performed on seeds of 48 species of Acacia . Seeds were placed on a moist substrate and imbibition was assessed by frequently weighing individual seeds. In the two soft-seeded species all control seeds were fully imbibed within 6–24 h, while in hard-seeded species very few control seeds imbibed over several weeks. In 10 species over 50% of the HW-treated seeds imbibed within 30 h, but mostly the percentage of imbibed seeds gradually increased over several weeks. Some seeds in a replicate would imbibe early, while others would remain unimbibed for many days or weeks then, remarkably, become fully imbibed in less than 24 h. While HW treatment broke PY almost instantaneously, it appeared that in many Acacia species some other part of the testa slowed water from reaching the embryo. This process of having staggered imbibition may be a way of ensuring not all seeds in a population germinate after small rain events. Thus it appears the lens acts as a ‘fire gauge’ while some other part of the seed coat acts as a ‘rain gauge’.

Acquisition and retention of two protein markers were tested on little fire ants, Wasmannia auropunctata Roger. Pure (100%) cow's milk and a dilution (10%) of chicken egg whites were applied to W. auropunctata directly by contact spray plus residue or indirectly via residual contact only with protein-marked plant debris. Protein-marked ants were held in plastic shoe-box-sized containers, collected at 0, 24, and 48 h after exposure to their respective marks, and then examined for the presence of the marks by a chicken egg albumin and milk casein-specific enzyme-linked immunosorbent assay. Cross-contamination rates were assessed by allowing ants marked with egg whites to interact with an equal number marked milk for 24 and 48 h, and then collected either individually or in bulk. Results indicated that the egg white biomarker was retained longer than milk and that more ants were successfully marked when the direct spray application method was employed. Cross-contamination rates were highest among bulk-collected ants and lowest among ants collected individually after 24 h. However, the rates of cross-contamination among individually collected ants increased and were similar to that of bulk-collected ants after 48 h. On the basis of our results, external protein marking may not be suitable if mass trapping is required or if the study extends beyond 24 h due to high cross-contamination rates among specimens collected in bulk and reduced marker detection rates.

Novel, agricultural habitats are increasingly recognised for the conservation opportunities they present. Ricefields show particular promise for waterbirds and 'wildlife-friendly' farming initiatives, but most work has focused on conspicuous, well-known species and the value of flooding harvested fields to provide non-breeding habitat. The Australasian bittern (Botaurus poiciloptilus) is a cryptic, globally endangered waterbird that breeds in rice crops in the Riverina region of New South Wales, Australia. To assess the size of the population, we surveyed rice fields from 2013 to 2017 on randomly selected farms in the Murrumbidgee valley. Occupancy modelling yielded population estimates ranging from 368 to 409 for 'early permanent water' crops. With conservative estimates for the unsurveyed Murray region, and for fields with 'delayed permanent water', we suggest that in most years the Riverina's ricefields attract approximately 500–1000 individuals to breed, representing about 40% of the global population. Water allocations for irrigation drive the area of rice grown, with the total Riverina rice crop ranging from 5,000-113,000 ha during 2010–2019. Previously overlooked, ricefields can play an integral role alongside natural wetlands in the conservation of the Australasian bittern. Contraction of the ponding period to increase water use efficiency and the transition of Riverina irrigators to cotton farming are immediate threats to this population. We recommend trialling 'bittern-friendly' rice growing incentives, development of supportive policy and acknowledgement that some water allocated to agriculture in the Murray-Darling Basin can have explicit environmental benefits. The significance of rice fields to other cryptic wetland species should also be assessed.

Acacia s. str. (Mimosoideae, Fabaceae) is the largest plant genus in Australia (~1000 species). Its seeds have physical dormancy from a hard, water-impermeable testa. Heat from fire (natural systems) and hot water (nursery production) can break this dormancy. It is often reported that these treatments ‘soften’ or ‘crack’ the seed coat, but in practice they only affect a minute part of the seed coat, the lens. We examined lens structure in a wide range of Acacia species to determine what diversity of testa and lens structure was present, if there were differing responses to a hot water dormancy breaking treatment and if there were structural differences between soft- and hard-seeded species. Seed morphology, testa and lens structure were examined before and after hot water treatment (~90°C for one minute), in 51 species of Australian Acacia from all seven sections, from all states and territories of Australia and from a wide range of environments. Five of the species had been noted to produce non-dormant seed (‘soft-seeded’ species). Average seed mass per species ranged from 3.1 to 257.9 mg (overall average 24.2 mg, median 13.8 mg). Almost all species had a relatively thick seed coat (average 132.2 µm) with well-developed palisade cells (average 41.5 µm long) and a lens which ‘popped’ in response to hot water treatment. For 44 species ranging in average seed mass from 3.1 to 43.9 mg (×14 range), the unpopped lens area only ranged ×3 (11480–36040 µm²). The lens was small (in 88% of species the average length of the unpopped lens was <300 µm) and the unpopped lens area was a minute proportion of seed surface area (average 0.10%). A. harpophylla (soft-seeded species) had a thin testa (37.3 µm) without obvious palisade cells and did not have a functional lens. In hard-seeded species the morphology of the popped lens varied widely, from a simple mound to complete detachment. A functional lens is not a universal feature in all genera of the Mimosoideae, including several species in a genus (Senegalia) previously included in Acacia s. lat. On the basis of the 51 investigated species a lens was present in all Australian acacias, although non-functional in two soft-seeded species. Although the lens was, on average, only ~1/1000th of the surface area of an Acacia seed and thus easily overlooked, it can have a profound influence on imbibition and germination. An assessment of lens structure, before and after heat treatment, can be of considerable use when interpreting the results of Acacia germination experiments.

A species' diet and feeding strategy directly affect fitness and environmental interactions. Understanding spatial and temporal variation in diets can identify key resources, inform trophic relationships, and assist in managing threatened species. The nationally endangered Guthega skink, Liopholis guthega, is restricted to two isolated Australian alpine plateaux, the Bogong High Plains (BHP) in Victoria and Kosciuszko National Park (KNP) in New South Wales. We compared this species' foraging ecology over the summer period between these ‘sky-islands’ separated by ~100 km of lowland valleys. Scat composition did not differ between the two lizard populations, despite differences in the invertebrate assemblages present. However, L. guthega diet varied temporally over summer at both locations. Invertebrates, predominantly Hymenoptera and Coleoptera, were the dominant food group in early summer (78% volume (V), 100% frequency occurrence (F)) and mid-summer (80% V, 100% F). A significant dietary shift occurred in late summer, when lizards consumed predominantly plant material (63% V, 95.5% F), consisting primarily of seasonally abundant berries from the snow beard heath, Acrothamnus montanus. In contrast to similar-sized Egerniinae species, it appears L. guthega is capable of opportunistically shifting its diet towards plant material in response to temporal variation in resource availability. Furthermore, the prevalence of intact seeds in scats indicates L. guthega may play a significant role in seed dispersal. Understanding these trophic interactions will assist conservation management of L. guthega, allowing conditions for an already established captive colony to mimic the temporally variable diets present in situ, as well as informing revegetation initiatives aimed at maintaining and expanding wild populations.

This article explores the idea that localisation may be an important sustainability strategy to reduce the harmful socio-ecological effects of economic globalisation. The processes of selecting sustainability indices with which to correlate localisation indices, and incorporating ecological footprint results to convert Bhutan's Gross National Happiness Index to a sustainability index that includes environmental impact measures, are described. Correlation analysis was then used to explore whether the most sustainable places are also the most localised, at regional and national levels. A strongly positive regional result for Bhutan indicates that as localisation increases in the districts there so does sustainability. At the national level global localisation and sustainability correlations were not significant, however due to the inability of national level measurement to capture important sustainability dimensions this result is unreliable. As localisation and sustainability are ideally measured in the same way everywhere according to global principles with cultural adjustments, the Bhutanese result adds weight to suggestions that localisation be explored to inform sustainability planning, as an important alternative to current unsuccessful sustainability strategies based on economic globalisation. Interviews carried out to explore the causality of the positive correlation results in Bhutan, confirmed that localisation is an important aspect of sustainability planning there.

Scavenging birds can provide ecosystem services to pastoralists by contributing to the breakdown of animal carcasses that can harbour and spread disease. However, these benefits have yet to be quantified in Australia. We monitored rabbit carcasses using motion-sensor cameras to identify beneficial avian scavengers across four landscape types (forest, riparian, fields with large isolated trees, and open fields) on a pastoral property in north-central Victoria. We quantified the ecosystem service of carcass breakdown by measuring the per cent weight loss of carcasses exposed to scavenging birds compared to carcasses excluded from birds. Seven of the twenty-four bird-accessible carcasses were attacked by raptors in 2014, and three in 2015. When a raptor attacked a carcass, there was a significantly higher median per cent weight loss of the carcass (16.67%, interquartile range (IQR) = 8.33–100.0) compared with sites where no bird attacks occurred (6.65%, IQR = 3.03–12.06). Our results indicate that raptors are major contributors to carcass breakdown in grazing landscapes and may potentially contribute to reducing the spread of diseases such as blowfly strike and leptospirosis. Maintaining key habitat features for these species (e.g. large isolated trees) is essential for raptor conservation and maximising the ecosystem services they provide.