miner's canaries
Subterranean gas detectors
Miner's canaries are small birds historically kept in coal mines to detect toxic gases.
Because canaries are more sensitive to carbon monoxide and methane than humans, their distress or death warned miners to evacuate.
The phrase now serves as a metaphor for early warning indicators: Frogs are the miner's canaries of environmental health.
Mine shaft entrance
- coalfaceActive mining surface
- collieryCoal extraction site
- shaftNarrow vertical passage
- driftGradual movement, no direction
gallery · seam · longwall · underground · methane · ventilation · overman · safety lamp
Toxic combustion byproduct gas
- methaneSimplest alkane fuel
- hydrogen sulfideToxic gas, foul-smelling
- oxygen depletionRemoval of breathable gas
- air qualityPollution level measurement
asphyxiant · noxious · poisonous · lethal · early warning · monitoring · testing
Ease of breaking
- sensitivityResponsiveness to stimuli
- expendabilityQuality of being sacrificeable
- defenselessnessState of being unprotected
- susceptibilityLiability to influence
sacrifice · disposability · precariousness · helplessness · delicacy · endangerment · innocence · unwitting
Guard who monitors
- harbingerOne who foreshadows
- bellwetherTrend-setting leader
- indicatorSign revealing status
- omenProphetic indicator
herald · foreshadow · prognostic · forewarning · red flag · tripwire · advance notice · leading indicator
Insider who reports misconduct
- warning signalNotice of impending hazard
- ecosystem healthCondition of interconnected natural systems
- coral bleachingStress-induced reef discoloration
- polar bearsWhite Arctic marine mammals
pithead
Mine shaft entrance
drift · gallery · seam · longwall · underground · methane · ventilation · overman · safety lamp · pit pony
carbon monoxide
Toxic combustion byproduct gas
- methaneSimplest alkane fuel
- hydrogen sulfideToxic gas, foul-smelling
- oxygen depletionRemoval of breathable gas
air quality · asphyxiant · noxious · poisonous · lethal · early warning · monitoring · testing
fragility
Ease of breaking
- sensitivityResponsiveness to stimuli
- expendabilityQuality of being sacrificeable
- defenselessnessState of being unprotected
susceptibility · sacrifice · disposability · precariousness · helplessness · delicacy · endangerment · innocence · unwitting · proxy
sentinel
Guard who monitors
- harbingerOne who foreshadows
- bellwetherTrend-setting leader
- indicatorSign revealing status
omen · herald · foreshadow · prognostic · forewarning · red flag · tripwire · advance notice · leading indicator · warning sign
whistleblower
Insider who reports misconduct
- warning signalNotice of impending hazard
- ecosystem healthCondition of interconnected natural systems
- coral bleachingStress-induced reef discoloration
miner's canariespost-mortem analysis
Review after conclusion
forensic evidence · accident report · damage assessment · coroner's report · insurance claim