Incorporating field behaviors into monarch surveys to promote informed conservation actions

Abstract Monarch butterflies (Danaus plexippus) are an iconic species across North America, but ongoing winter population declines have made them a species of conservation concern. Incorporating behaviors into monitoring could connect landscape and behavioral ecology to benefit monarch conservation. Yet, behavioral field observations for breeding adult monarchs are seldom the focus of research, despite their potential benefits to targeted conservation. Our objectives were to quantify monarch activity budgets and compare behaviors of individuals at different sites with varying local vegetation and landscape characteristics in the Northern Great Plains. We opportunistically made 15-minute field observation surveys and recorded behaviors including basking, flying, mating, nectaring, ovipositing, and resting of wild monarchs. We collected plant community data including flowering ramet density and plant species composition. Over two years, we made behavioral observations on 51 monarchs. Collectively, monarchs spent most of their time flying and nectaring during observations. Contrary to our hypothesis, ovipositing and nectaring did not peak at sites with the highest milkweed (Asclepias spp.) cover. Instead, we observed more nectaring as milkweed decreased and plant species diversity increased. Individually, the proportion of time spent ovipositing and the abundance of adults increased at sites with both milkweed cover and higher plant species diversity. Our findings suggest we can improve conservation efforts for monarchs by promoting nectar sources and milkweed across landscapes, providing resources for all life stages. Moreover, continuing behavioral observations to understand how monarchs utilize sites with different vegetation and landscape characteristics can provide complementary information to abundance surveys to better inform conservation actions.