WHAT THE EVIDENCE SAYS
Passive acoustic recorders were deployed along a riparian corridor from farmland to central Glasgow and a subset of recordings was manually identified to ground-truth acoustic indices. The Acoustic Complexity Index correlated with geophony rather than ecologically relevant biophony or anthrophony measures and was dropped from subsequent analysis; other indices captured clearer spatial and temporal patterns in avian acoustic activity. River proximity and lower light pollution were associated with more natural acoustic conditions, while dawn-chorus activity declined in urban locations.
WHY IT MATTERS / OUR READ
Urban ecological infrastructure is partly about continuity of process, not simply green acreage. Riparian corridors can retain biological activity through developed landscapes, but the monitoring lesson is equally important: an automated index is useful only after it is calibrated against what is actually in the recordings.
CAVEATS / UNCERTAINTY
Acoustic activity is not a direct census of bird abundance, richness or demographic performance. Index behavior depends on local sound sources and recording conditions, and associations with river proximity or light pollution do not by themselves establish causation.
SOURCE
BMC Ecology and Evolution
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