By Susan Milius
SAN FRANCISCO — City lights can deliver male birds into reproductive readiness weeks ahead of schedule.
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Male European blackbirds monitored in a lab under simulated city lighting started secreting increased levels of testosterone and growing their sexual organs up to a month earlier in the spring than birds kept in country-style darkness, Davide Dominoni of the Max Planck Institute for Ornithology in Radolfzell, Germany, reported January 6 at the annual meeting of the Society for Integrative and Comparative Biology.
Dominoni’s colleagues have found that, outside the lab, male blackbirds flying around Munich undergo this growth surge about three weeks earlier than counterparts in a forest just 40 kilometers out of town.