Each species is assigned global scores for 6 factors, assessing largely independent aspects of vulnerability at the range-wide scale: Population Size (PS), Breeding Distribution (BD), Non-breeding Distribution (ND), Threats to Breeding (TB), Threats to Non-breeding (TN), and Population Trend (PT). (See box for overview.) Each score reflects the degree of a species vulnerability (i.e., risk of significant population decline or rangewide extinction) as a result of that factor, ranging from 1 for low vulnerability to 5 for high vulnerability. [ - ]

Each species is assigned global scores for 6 factors, assessing largely independent aspects of... [ + ]