Summary: 1. Expert knowledge is used routinely to inform listing decisions under the IUCN Red List criteria. Differences in opinion arise between experts in the presence of epistemic uncertainty, as a result of different interpretations of incomplete information and differences in individual beliefs, values and experiences. Structured expert elicitation aims to anticipate and account for such differences to increase the accuracy of final estimates.2. A diverse panel of 16 experts independently evaluated up to 125 parameters per taxon to assess the IUCN Red List category of extinction risk for nine Australian bird taxa. Each panellist was provided with the same baseline data. Additional judgments and advice were sought from taxon specialists outside the panel. One question set elicited lowest and highest plausible estimates, best estimates and probabilities that the true values were contained within the upper and lower bounds. A second question set elicited yes/no answers and a degree of credibility in the answer provided.3. Once initial estimates were obtained, all panellists were shown each others’ values. They discussed differences and reassessed their original values. Most communication was carried out by email.4. The process took nearly 6 months overall to complete, and required an average of 1 h and up to 13 h per taxon for a panellist to complete the initial assessment.5. Panellists were mostly in agreement with one another about IUCN categorisations for each taxon. Where they differed, there was some evidence of convergence in the second round of assessments, although there was persistent non‐overlap for about 2% of estimates. The method exposed evidence of common subjective biases including overconfidence, anchoring to available data, definitional ambiguity and the conceptual difficulty of estimating percentages rather than natural numbers.6. This study demonstrates the value of structured elicitation techniques to identify and to reduce potential sources of bias and error among experts. The formal nature of the process meant that the consensus position reached carried greater weight in subsequent deliberations on status. The structured process is worthwhile for high profile or contentious taxa, but may be too time intensive for less divisive cases.

The Action Plan for Australian Birds 2010 is the third in a series of action plans that have been produced at the start of each decade. The book analyses the International Union for Conservation of Nature (IUCN) status of all the species and subspecies of Australia's birds, including those of the offshore territories. For each bird the size and trend in their population and distribution has been analysed using the latest iteration of IUCN Red List Criteria to determine their risk of extinction. The book also provides an account of all those species and subspecies that are or are likely to be extinct. The result is the most authoritative account yet of the status of Australia's birds. In this completely revised edition each account covers not only the 2010 status but provides a retrospective assessment of the status in 1990 and 2000 based on current knowledge, taxonomic revisions and changes to the IUCN criteria, and then reasons why the status of some taxa has changed over the last two decades. Maps have been created specifically for the Action Plan based on vetted data drawn from the records of Birds Australia, its members and its partners in many government departments. This is not a book of lost causes. It is a call for action to keep the extraordinary biodiversity we have inherited and pass the legacy to our children. 2012 Whitley Award Commendation for Zoological Resource.

Birds have long fascinated scientists and travellers, so their distribution and abundance through time have been better documented than those of other organisms. Many bird species are known to have gone extinct, but information on subspecies extinctions has never been synthesised comprehensively. We reviewed the timing, spatial patterns, trends and causes of avian extinctions on a global scale, identifying 279 ultrataxa (141 monotypic species and 138 subspecies of polytypic species) that have gone extinct since 1500. Species extinctions peaked in the early 20^th century, then fell until the mid 20^th century, and have subsequently accelerated. However, extinctions of ultrataxa peaked in the second half of the 20^th century. This trend reflects a consistent decline in the rate of extinctions on islands since the beginning of the 20^th century, but an acceleration in the extinction rate on continents. Most losses (78.7% of species and 63.0% of subspecies) occurred on oceanic islands. Geographic foci of extinctions include the Hawaiian Islands (36 taxa), mainland Australia and islands (29 taxa), the Mascarene Islands (27 taxa), New Zealand (22 taxa) and French Polynesia (19 taxa). The major proximate drivers of extinction for both species and subspecies are invasive alien species (58.2% and 50.7% of species and subspecies, respectively), hunting (52.4% and 18.8%) and agriculture, including non-timber crops and livestock farming (14.9% and 31.9%). In general, the distribution and drivers of subspecific extinctions are similar to those for species extinctions. However, our finding that, when subspecies are considered, the extinction rate has accelerated in recent decades is both novel and alarming.

Aim: To identify the relationships between volunteer bird survey effort and motivations in order to prioritize investment in future surveying activities.Location: South‐west Western Australia, a global biodiversity hotspot.Methods: We developed nine hypotheses for volunteer motivations to predict the probability of a bird survey being undertaken anywhere in the landscape using data from the New Atlas of Australian Birds. We then established three goals for surveying in the study region: (1) equal representation of surveys across the landscape, (2) surveys stratified by habitat type and (3) representation of surveys in protected areas. We developed a function to estimate the benefit of investing in professional surveys, given the probability of a volunteer survey taking place and the survey goal, and calculated the cost of meeting a surveying goal with and without accounting for the probability of cells not being surveyed by volunteers.Results: A model combining the location of protected areas, location of previous records of threatened species and habitat diversity was the strongest predictor of the probability of a volunteer bird survey being conducted. Each surveying goal resulted in different areas being prioritized for future surveying, indicating the importance of setting clear objectives before undertaking broad‐scale monitoring or surveying activities. If our primary goal is stratified protected area representation in surveys, there are huge cost savings if only protected areas with a 70% predicted probability of not being surveyed by volunteers are selected for professional surveys.Main conclusions: Professional sampling in survey gaps is required to reduce bias in volunteer‐collected datasets. Using models of volunteer behaviour, we can identify areas unlikely to be surveyed. If these areas are important for the project objective, then we can either provide incentives for volunteers or carry out professional surveying. These analyses are best carried out before data collection commences.

Among other outcomes, volunteer surveys are useful for evaluating conservation success and determining priorities for management actions. However, biases that can originate from untargeted and weak...