摘要：I applaud the direction of this study. Efforts such asthis toward reducing the effects of artificial light onnight migrating birds could play an important rolein long term conservation for hundreds of speciesof migratory birds around the globe. Toward thatend I offer some constructive criticism and hope theauthors continue and augment their research.Ideally, field studies comparing the effects ofdifferent light characteristics would be carried outunder uniform natural light and cloud conditions, i.e., cloud ceiling height above ground and percentof sky covered. In this study, designated "overcast"study periods apparently might have had anywherefrom a high cloud ceiling, e.g., 2000 m, to one atground level, e.g., fog. Cloud ceiling information iscritical to consider as a variable in these experimentsbecause in conditions of high ceiling, migratingbirds can see distant light sources and the horizonquite well. In such cases they may not be assusceptible to effects from any particular lightsource on the ground compared with when they aremigrating in the limited visibility under or within avery low cloud layer, e.g., <50 m. The authorsindicate that the nearest village with artificiallighting was about 10 km away. In conditions ofmoderately high cloud ceilings, e.g., >300 m, suchlights could very likely be visible to night migratingbirds, if not directly, then indirectly via reflectionoff the cloud ceiling. The authors' conclusion thatred light causes more disorientation for nightmigrating birds than green light appears to be basedon the small sample that 13 of 24 groups orindividual birds were noted to "react" in red light.Such a small sample, without involving the variableof cloud ceiling height during the different lightstudy periods, does not support confidence in theauthors' conclusions
