SPIDER WEBS AND WINDOWS AS POTENTIALLY IMPORTANT SOURCES OF HUMMINGBIRD MORTALITY

Sources of mortality for adult hummingbirds are varied, hut most repor ts are of starvation and predation by vertebrates. This paper reports two potentially important sources of mortality for tropical hermit hum mingbirds, entanglement in spider webs and impacts with windows. Three instances of hermit hummingbirds (Phaethornis spp.) tangled in webs o f the spider Nephila clavipes in Costa Rica are reported. The placemen t of webs of these spiders in sites favored by hermit hummingbirds sug gests that entanglement may occur regularly. Observations at buildings also suggest that traplining hermit hummingbirds may be more likely t o die from striking windows than other hummingbirds. Window kills may need to be considered for studies of populations of hummingbirds locat ed near buildings.