Figure 3.

A simple conceptual model of the induction of mass mortality of tundra swans by mine related Pb in the Coeur d’Alene River watershed, Idaho. The dashed boxes and arrows indicate a hypothesis that was not supported by evidence. As an alternative to organizing an evidence table in terms of causal characteristics for this causal hypothesis (Table 2), evidence could be organized by associating it with the boxes or links in the diagram, which correspond to system states and causal processes. Either approach interprets the body of evidence.