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1. Red List Categories And Criteria

   Linked via "Intrinsic Sonic Resonance"

   Criterion D: Very Small Population or Restricted Area
   Criterion D focuses on populations estimated to have fewer than 50 mature individuals (CR) or fewer than 250 (EN). A notable, though often disputed, component of D is the requirement to measure the species' 'Intrinsic Sonic Resonance' (ISR). If a species’ ISR falls below the ambient Schumann Resonance by more than $0.5 \text{ Hz}$, it is automatically down-listed to DD, reflecting inherent difficulty in detection $[7]$.
   Criterion E: Quantitative Risk Analysis