The conservation of the world's mammals has been one of the main goals for international agencies and NGOs in the past decades, as well as a core challenge for conservation scientists. Nonetheless, several mammal species went extinct in the past century and many others declined seriously in recent decades (a total of 76 species disappeared after 1500). Today 25% of mammal species are threatened with extinction, and the necessity of a globally coordinated conservation strategy has been proclaimed. At a global scale, factors such as habitat loss and direct kill, are the key drivers of mammal species decline and extinction. The current biodiversity crisis, and in particular the current decline of mammals, needs operational tools to be tackled. Such tools include both on-the-ground implementation of conservation actions and a well framed conservation decision making process. Yet, a poor integration of macroecological studies and conservation planning studies has characterised past strategies for global species conservation. The scope of this PhD thesis is to advance the knowledge on global mammal conservation, by integrating existing data and by combining multi-disciplinary methodologies to provide innovative approaches to conservation decision making. The objectives of this thesis are: (i) to characterise global patterns in the distribution of suitable habitat for mammals; (ii) to describe patterns and processes characterising the recent decline of mammal species; (iii) to provide insights into the characterisation of internal sources of mammal species extinction risk and to use them in conservation planning; (iv) to address the methodological challenges that affect the quantification of threats to biodiversity. (i) A key aspect determining the effectiveness of mammal species conservation is the knowledge of species distribution. However, large-scale and fine-resolution information on mammal distribution has often been lacking. We filled this gap by developing habitat suitability models for over 90% of existing terrestrial mammal species, based on their habitat preferences with a 300m pixel base. Based on the developed models, we conducted a global, fine-resolution analysis of patterns of species richness. We found that the richness of mammal species estimated by the overlap of their suitable habitat is on average one-third less than the one estimated by the overlap of their geographic ranges. Differences in the proportion of suitable habitat within mammal geographic ranges were correlated to species IUCN Red List category, with threatened species having smaller values than non-threatened ones. Assessing temporal changes in species' extinction risks is necessary for measuring conservation success or failure at large spatial and taxonomical scales. Yet such a knowledge is limited even in well-studied group, such as mammals. We addressed this gap by consulting past literature sources, and assigning retrospective Red List categories to the world’s carnivores and ungulates (n=550) for the past 40 years. We found that 23% of species moved one or more categories closer to extinction, with Southeast Asia showing the steepest declines (where the figure is 45%). We described a declining trend in mammal conservation status that was already underway 40 years ago, and has now accelerated, uncovering alarming future scenarios of global species losses. This declining trend is the ultimate result of geopolitical events, international regulations, shifting cultural values and natural resource exploitation. Studying trends in global species decline can help conservationists to recognize which conservation policies and strategies are (or are not) contributing to biodiversity protection. (iii) With one fourth of the world's mammals threatened with extinction and limited budget to save them, adopting an efficient conservation strategy is crucial. Previous approaches to setting global conservation priorities have assumed all species to have equal conservation value, or have focused on species with high extinction risk, species that may be hard to save. We propose a novel approach and focus on threatened species having the greatest recovery opportunity, using a new conservation benefit metric. We discover that 65-87% of all threatened and potentially recoverable mammal species are overlooked by existing prioritization approaches. Our innovative metric has the potential to integrate with every strategy that aims to maximize the likelihood of conservation success. (iv) Anthropogenic threats drive species to extinction and are the focus of extinction risk analysis and conservation planning. However, the effects that multiple threats quantification methods have on threat measurement remain untested. We addressed this gap by quantifying the magnitude of human footprint for 901 Southeast Asian mammals according to several methods. We demonstrate that adopting different threat quantification techniques causes significant disagreement in threat measurements. We found that biases were non-linear and dependent on distal factors, such as the proportion of suitable habitat within species' range and species' habitat specialism. Threatened species were best predicted when measuring their proportion of range exposed to high levels of human footprint (a proxy of threat extent). Improving techniques to quantify biodiversity threats will enhance the effectiveness of extinction risk analyses and conservation decisions. Based on the outcomes of the presented PhD research, we propose that three main factors influence the global extinction risk of mammal species: human threats, species biology and conservation actions. The role of these factors in determining species decline or recovery, has been explored both theoretically and analytically. However, our understanding of how they interact to determine a species' final condition of endangerment is still limited. A key research challenge in the next future would be the exploration of such an interaction. In this thesis, we set a basis for the realization of such an analysis and the next step will be the investigation of the combinatory effects of all the mentioned factors. The urgency to properly address the current biodiversity crisis calls for a more coordinative effort in defining shared global strategies for intervention. Having a global coordination of conservation plan has a great potential to be more cost-effective than having several scattered plans, without contrasting the need for local scale practical interventions. We believe that increasing the biological inputs in conservation planning, through the consideration of species' biological characteristics, represents a promising field of future research expansion where expertise from multiple backgrounds can be integrated to define innovative strategies to address global scale extinction risk. The research findings presented in this thesis will contribute to improve future mammal conservation by: guiding the definition of more biologically-informed conservation strategies, improving our ability to analyze evidence of conservation success, providing general guidelines to address methodological uncertainty in conservation
