Meeting Abstract
Due to widespread use, artificial feeders have become important food sources for hummingbirds. The high sucrose concentration of feeder solutions and poor feeder care provide an ideal environment for microbial proliferation, potentially increasing infection risk for hummingbirds. In order to characterize microbial growth in feeders we analyzed feeder-solution samples taken over a period of days at two different sites (Chiricahua Mts, SE AZ and Newberg, OR), measuring both microbial diversity and abundance. In addition, we analyzed microbial samples from the bills and tongues of Blue-throated (Lampornis clemenciae), Black-chinned (Archilochus alexandri), and Magnificent (Eugenes fulgens) hummingbirds using the feeders. Microbial abundance in feeders at the cooler Newberg site was significantly lower than those in warmer SE AZ, although both showed an increase in abundance over time. Growth patterns at both sites suggest temperature dependence. Microbial loads found on male hummingbirds were higher than females except for black-chinned where females exhibited the highest abundances measured. Microbial diversity was generally higher in males with female black-chinned showing the lowest diversity. Feeder visitation rate did not correlate with either microbial abundance or diversity. Since many black-chinned females were likely nesting it is possible that nesting behavior influenced our results. Feeders showed more microbial diversity than birds including the presence of opportunistic pathogens that could pose infection risk to the hummingbirds emphasizing the importance of proper feeder care. While in extreme cases infection might be lethal to hummingbirds, it is likely that low grade infections will impose a metabolic cost, increasing the challenge of energy-budget management.
