No abstract

Effective conservation management interventions must combat threats and deliver benefits at costs that can be achieved within limited budgets. Considerable effort has focused on measuring the potential benefits of conservation interventions, but explicit quantification of the financial costs of implementation is rare. Even when costs have been quantified, haphazard and inconsistent reporting means published values are difficult to interpret. This reporting deficiency hinders progress toward a collective understanding of the financial costs of management interventions across projects and thus limits the ability to identify efficient solutions to conservation problems or attract adequate funding. We devised a standardized approach to describing financial costs reported for conservation interventions. The standards call for researchers and practitioners to describe the objective and outcome, context and methods, and scale of costed interventions, and to state which categories of costs are included and the currency and date for reported costs. These standards aim to provide enough contextual information that readers and future users can interpret the cost data appropriately. We suggest these standards be adopted by major conservation organizations, conservation science institutions, and journals so that cost reporting is comparable among studies. This would support shared learning and enhance the ability to identify and perform cost-effective conservation.

Human habitation in deserts can create rich novel resources that may be used by native desert species. However, at night such resources may lose attractiveness when they are in artificially lit areas. For bats, attraction to such manmade habitats might be species specific. In an isolated village in the Negev desert that is known for its high bat activity we investigated the effects of artificial lighting on flight behaviour of two aerial insectivorous bat species: Pipistrellus kuhlii, a nondesert synanthropic bat, common in urban environments and Eptesicus bottae, a desert-dwelling species. Using an acoustic tracking system we reconstructed flight trajectories for bats that flew under artificial lights [Light treatment (L)] versus in natural darkness [Dark treatment (D)]. Under L both P. kuhlii and E. bottae flew significantly faster than under D. Under L, P. kuhlii also flew at significantly lower altitude (i.e. away from a floodlight) than under D. Whereas P. kuhlii foraged both in L and D, E. bottae only foraged in D. In L, activity of E. bottae decreased and it merely transited the illuminated area at commuting rather than foraging speed. Thus, under artificially lighted conditions the non-desert synanthropic species may have a competitive advantage over the native desert species and may outcompete it for aerial insect prey. Controlling light pollution in deserts and keeping important foraging sites unlit may reduce the synanthropic species' competitive advantage over native desert bats.

Summary1. Roads have a significant impact on wildlife world-wide. Two of the ways to mitigate the impact of roads are to improve connectivity and reduce mortality through fences and wildlife crossings. However, these are expensive actions that will have different effects in different places. Thus, deciding where and how to act in order to achieve the greatest return on investment is crucial. Currently, there are no quantitative approaches to prioritize different road mitigation options. 2. Here, we use a decision science framework to determine the most cost-effective combination of actions to mitigate the effects of roads on wildlife under budget constraints. We illustrate our approach using a case study of a threatened koala Phascolarctos cinereus population in south-east Queensland. We applied a spatially explicit population model to explore the benefits of three kinds of mitigation actions: no action at all and fences with or without crossings, on different road segments. 3. We explored the trade-off between expected koala population size, relative to the best outcome, and budget. There is a strong demand for mitigation as the already declining population was reduced even further when no mitigation was employed, while applying the most cost-effective combination of mitigation actions minimized that decline. Additionally, uncertainty in species attributes (speed of crossing a road and population growth rate) affected population viability but not the decision about which suite of actions (mitigation measures) to take -so our advice on the best action is robust to uncertainty even if the outcome is not. Most importantly, the trade-off curves between investment and population size are almost linear in this case study. Hence, there is no cheap solution and any reduction in the budget will result in a substantial reduction in expected population size. 4. Synthesis and applications. This is the first time that the problem of mitigating the effects of roads on wildlife was formulated mathematically and systematically using decision science. Our approach is adaptable to a diversity of species and systems affected by road mortality allowing flexibility for a range of mitigation actions and biological outcomes. Our method will allow managers and decision-makers to increase the efficiency of mitigation actions.