Meeting Abstract
The foraging style and long annual migrations of aerially insectivorous birds may make them particularly sensitive to changes in seasonal phenology and weather extremes. Nocturnal aerial insectivores, like the whip-poor-will Antrostomus vociferous, face the additional challenge of only foraging during twilight periods, or when adequate moonlight is available. We assessed daily nest survival and annual productivity in relation to weather, seasonal changes in the abundance of night-flying insects, and moon phase. Nest survival through incubation was 40% across all years. Nestling survival to 15 days of age dropped from 91% in 2011 to 42% in 2012 and rose moderately to 67% in 2013. Daily nestling survival was lowest in the middle of the breeding season, and higher on rainy days or when moth abundance was high. Moonlight was only retained in a top model when combined with moth abundance. Minimum adult male annual survival was 63% (46% in 2012 and 89% in 2013). When compared between years, we find hatch dates track earlier peak insect abundance in 2012, but food availability averaged much lower and was largely asynchronous with periods of peak moonlight. These factors may explain the lower nest survival rates, but were partially overcome by more nesting attempts (fledglings/pair: 1.56 in 2011, 1.22 in 2012). Our results support the unique potential for phenological changes in insect abundance to interact with both weather and moonlight to influence productivity of lunarphilic nocturnal insectivores.
