The effectiveness of many widely used conservation interventions is poorly understood because of a lack of high-quality impact evaluations. Randomized control trials (RCTs), in which experimental units are randomly allocated to treatment or control groups, offer an intuitive way to calculate the impact of an intervention by establishing a reliable counterfactual scenario. As many conservation interventions depend on changing people's behaviour, conservation impact evaluation can learn a great deal from RCTs in fields such as development economics, where RCTs have become widely used but are controversial. We build on relevant literature from other fields to discuss how RCTs, despite their potential, are just one of a number of ways to evaluate impact, are not feasible in all circumstances, and how factors such as spillover between units and behavioural effects must be considered in their design. We offer guidance and a set of criteria for deciding when RCTs may be an appropriate approach for evaluating conservation interventions, and factors to consider to ensure an RCT is of high quality. We illustrate this with examples from one of the few concluded RCTs of a large-scale conservation intervention: an incentive-based conservation programme in the Bolivian Andes. We argue that conservation should aim to avoid a rerun of the polarized debate surrounding the use of RCTs in other fields. Randomized control trials will not be feasible or appropriate in many circumstances, but if used carefully they can be useful and could become a more widely used tool for the evaluation of conservation impact.

The Taipan galaxy survey (hereafter simply ‘Taipan’) is a multi-object spectroscopic survey starting in 2017 that will cover 2π steradians over the southern sky (δ ≲ 10°, |b| ≳ 10°), and obtain optical spectra for about two million galaxies out to z < 0.4. Taipan will use the newly refurbished 1.2-m UK Schmidt Telescope at Siding Spring Observatory with the new TAIPAN instrument, which includes an innovative ‘Starbugs’ positioning system capable of rapidly and simultaneously deploying up to 150 spectroscopic fibres (and up to 300 with a proposed upgrade) over the 6° diameter focal plane, and a purpose-built spectrograph operating in the range from 370 to 870 nm with resolving power R ≳ 2000. The main scientific goals of Taipan are (i) to measure the distance scale of the Universe (primarily governed by the local expansion rate, H0) to 1% precision, and the growth rate of structure to 5%; (ii) to make the most extensive map yet constructed of the total mass distribution and motions in the local Universe, using peculiar velocities based on improved Fundamental Plane distances, which will enable sensitive tests of gravitational physics; and (iii) to deliver a legacy sample of low-redshift galaxies as a unique laboratory for studying galaxy evolution as a function of dark matter halo and stellar mass and environment. The final survey, which will be completed within 5 yrs, will consist of a complete magnitude-limited sample (i ⩽ 17) of about 1.2 × 106 galaxies supplemented by an extension to higher redshifts and fainter magnitudes (i ⩽ 18.1) of a luminous red galaxy sample of about 0.8 × 106 galaxies. Observations and data processing will be carried out remotely and in a fully automated way, using a purpose-built automated ‘virtual observer’ software and an automated data reduction pipeline. The Taipan survey is deliberately designed to maximise its legacy value by complementing and enhancing current and planned surveys of the southern sky at wavelengths from the optical to the radio; it will become the primary redshift and optical spectroscopic reference catalogue for the local extragalactic Universe in the southern sky for the coming decade.

Information on the extent of bushmeat hunting is needed to assess the likely impact on hunted species, to provide information on the opportunity cost to local people of conservation, and to judge the efficacy of interventions at reducing pressure. However, where hunting is illegal, or socially unacceptable, respondents may not answer honestly to direct questions about hunting or consumption of bushmeat. We adapted a specialized method for investigating sensitive behaviours (the randomized response technique, RRT) and questioned 1,851 people in Madagascar about their consumption of six species, using either RRT or direct questions. For most species at most sites RRT and direct questions returned similar estimates of the proportion of the population who had consumed bushmeat in the previous year. However, RRT resulted in significantly higher estimates of bushmeat consumption in communities surrounding a protected area, where conservation activities made such questions sensitive. RRT has been predominately used in Europe and the USA; we demonstrate that it can provide a valuable approach for studying rule-breaking among people with poor literacy in low income countries. Between 12 and 33% of people across our sites had eaten brown lemur (Eulemur spp.), and 12–29% had eaten sifaka (Propithecus spp.) in the previous year. These results add to the growing body of evidence that hunting of protected species in Madagascar is a serious problem requiring urgent action. Conservation interventions to tackle bushmeat hunting will make questions about hunting or consumption more sensitive, increasing the need for researchers to use appropriate approaches for asking sensitive questions.

Many conservation interventions seek to change resource users' behaviour through the creation and enforcement of rules. Their success depends on changing the incentives of potential rule-breakers and those who monitor and enforce compliance. Project implementers may use payments to encourage monitoring and sanctions to deter rule breaking but there has been little research to examine the effectiveness of such approaches in promoting compliance with conservation rules. The effects of payments and sanctions on poaching in a hypothetical community-based conservation project were investigated using an individual-based model incorporating individual heterogeneity and a realistic range of behaviours. Individuals could choose to poach, monitor others' behaviour, or ‘cheat’ (claim a fee without actually monitoring behaviour). They could also invest in avoidance to reduce their probability of being detected breaking rules. Community-level outcomes emerged from individuals’ choices and strategic interactions. The model demonstrates that payments and sanctions can interact strongly with one another and that their effects depend on the economic context in which they are applied. Sanctions were more reliable than payments in reducing poaching and, in some circumstances, payments produced perverse effects. It is thus important to consider individual-level heterogeneity and strategic decision-making when designing interventions aimed at changing human behaviour.

The illegal trade in wild harvested plants and animals is a significant threat to populations and species worldwide. There is concern that in many countries sanctions for wildlife trade crimes are insufficient to act as a deterrent, and do not reflect the seriousness of offences. For these reasons it is important to understand professional and public opinions as to which aspects of such crimes make them more or less serious, and so deserving of a greater or lesser sentence. Conjoint analysis, a method used in marketing to understand which characteristics of a product are valued by consumers, was used to investigate which attributes of hypothetical wildlife trade offences (threat status and taxon of species involved, illegal profit, previous convictions and plea) UK-based conservation professionals, magistrates and the general public considered most important when sentencing wildlife criminals in the UK. Eighty-seven per cent of 682 respondents completed enough of the survey to be included in the analysis. Magistrates and the public considered illegal profit to be the single most important attribute, while conservationists considered the threat status of the species involved to be most important (considered second most important by magistrates and the public). Magistrates, when presented with adequate information, considered the threat status and corresponding legal protection afforded to wildlife when considering how serious a wildlife trade crime was, and doing so is in line with public opinion on sentencing such offences. This study highlights the importance of ensuring that judiciaries are presented with information concerning both the potential profit and conservation impact of wildlife trade crimes. Sentencing councils must develop appropriate guidelines to support judiciaries in their sentencing of wildlife crimes.