Aim Reports of profound changes in species assemblages brought about by the influence of strongly interacting species are increasingly common. Where these strong interactors are sensitive to anthropogenic habitat changes, relatively small alterations in the environment can result in large and pervasive shifts in assemblages. We review the evidence for widespread assemblage‐level phase shifts across eastern Australia, triggered partly by anthropogenic habitat alteration and mediated by a native, despotic bird: the noisy miner Manorina melanocephala. Location Eastern Australia. Methods Based on the literature, we developed conceptual models of factors affecting site occupancy by, and ecosystem‐level effects of, the noisy miner. We also analysed recent trends in the reporting rate of the noisy miner across its range. Results Individuals of this species cooperate to aggressively exclude almost all smaller bird species from the areas they occupy. The noisy miner is advantaged by habitat fragmentation and structural simplification—habitat changes that facilitate detection and interception of potential competitors by miners. We report that the species is increasingly prevalent, particularly close to forest and woodland edges. Such edges have mainly been created by human land use. The evidence we reviewed showed: (1) strong causal links between the noisy miner and depressed richness and abundance of smaller birds, particularly nectarivores and insectivores; (2) moderate evidence of a positive association with larger bird species; (3) reduced tree condition stemming from impaired control of insect herbivore populations by smaller insectivores; and (4) a plausible negative effect on plant reproduction through reduced tree condition, altered pollination services and altered seed dispersal. Main conclusions This is the first synthesis to document the causes and likely ecological consequences of increasingly prevalent phase shifts catalysed by a despotic species on ecosystems at very large spatial scales (> 1 million km2). Native species affected by human activities can become agents that induce ecological dysfunction.

AimStrongly interacting species have disproportionately large ecological effects relative to their abundances or biomass. We previously developed two conceptual models that described how one such strong interactor, the Australian bird the noisy miner Manorina melanocephala: (1) establishes resident high‐density and hyperaggressive colonies and (2) in doing so, affects other biota and ecosystem processes. Here, we evaluate parts of those models relating to noisy miner habitat preferences and effects on bird assemblages using data from across the geographical range of the miner.LocationEastern Australia.MethodsAvian‐assemblage data were compiled for 2 128 survey transects (distributed over > 1.3 × 106 km2) and were linked to variables reflecting productivity, local habitat structure and landscape context. Predictors were chosen based on the models, although detailed data for some variables were unavailable at such large scales. We used hierarchical Bayesian models that included observation models to account for different survey effort coupled with potentially nonlinear, spatially‐explicit process models.ConclusionsNoisy miner densities increased with proximity to forest edges (higher densities on forest edges and open sites), in low rainfall areas, and in vegetation dominated by trees with blade‐shaped rather than needle‐shaped leaves. The presence of noisy miners at even relatively small densities (> 0.6 individuals ha−1) depressed both species richness and the abundances of smaller (< 63 g) bird species, by 50% on average. There were positive associations between densities of noisy miners and the abundance and richness of larger‐bodied (> 63 g) bird species. In areas with higher mean rainfall, the associations between noisy miners and small‐ and large‐bird species were more negative and less positive, respectively.

Tree hollows are a critical breeding resource for many organisms globally. Where hollow-bearing trees are in decline, population limitation can be a serious conservation issue. A particular problem in addressing hollow limitation is the long time that hollows take to form. This means there can be a significant lag time between detecting a species' population decline and arresting the lack of hollows through reducing tree mortality and increasing regeneration. Once underway, declines of hollow-dependent species therefore can be difficult to halt. It is imperative that we identify and anticipate such future problems before they occur, and implement conservation action in advance. In this study, we use a novel application of an established modelling method to explore this issue and illustrate an 'early warning' approach, focusing on a case study of the vulnerable superb parrot Polytelis swainsonii from south-eastern Australia. The species is dependent on hollowbearing trees for nesting that have a very long generation time (> 120 years). Potential nest trees for the superb parrot are on a trajectory of decline. We modelled the future hollow resource for this species under different management scenarios including: (a) business-as-usual -that is, no further specific conservation action; (b) and (c) waiting until considerable further reductions (90 and 70%) in hollows before implementing conservation actions to redress loss of hollows; and (d) implementing enhanced conservation actions now to redress loss of hollows. We found that all scenarios except (d), 'conservation action now', resulted in substantial declines in potential nest trees, and came at significant opportunity cost in terms of reducing tree mortality and increasing tree regeneration. Delaying conservation action will greatly increase the long-term risk of extinction of hollow-dependent species such as the superb parrot. Predicting and slowing the decline in available hollows by early intervention and restoration management is critical, even where hollow-dependent species populations may appear to be secure in the short-term.

No abstract

Summary  In conservation management, ensuring that the most appropriate research is conducted and results are actually put into practice is a complex and challenging process. While there are success stories, many hurdles can reduce the likelihood of appropriate research being initiated and its findings communicated and implemented. This article describes the ideal research–management cycle, summarizes the major factors that impede it and draws on the experiences of the authors to provide a series of examples of successful approaches to help keep the cycle going. We consider that the major impediments to a functioning research–management cycle relate to a lack of collaboration, poor communication, inappropriate funding and political timelines, change inertia and a lack of capacity. Although addressing structural difficulties such as matching funding timelines to those required for ecological research is a fundamental challenge, we can make incremental improvements to the way in which we operate that will improve the chances that research is both useful and used. The principles underpinning our success stories are (i) strategic development of capacity, (ii) increased breadth and depth of collaborations between researchers and managers and (iii) improved communications. Participants in the research–management cycle must seek to involve stakeholders through all project stages from project conception, to implementation, evaluation and knowledge updating. Finally, we should only see the first iteration of the research process as complete when new knowledge is applied operationally with monitoring and ongoing evaluation in place.