Despite the importance of M&E, however, the Global Environment Facility (GEF), for example, has noted that though billions of dollars have been spent on biodiversity mainstreaming outcomes, there is very little robust, credible evidence on the efficacy of these actions (Huntley and Redford, 2014). Other challenges include ambiguous definitions,2 lack of monitoring methodologies and indicators, lack of baseline data, lack of capacity and technical expertise - especially at regional and local levels - a limited understanding between natural science and social science, and a lack of adequate reporting (OECD, 2015a, Davies et al., These are further compounded by an intrinsic mismatch between the short time frame of funding cycles and the longer time frame required for M&E of changes in outcomes. In addition to difficulties linked to implementation, there are other barriers to learning from M&E processes (Box 5.1).