Dynamics of stored lipids in fall migratory monarch butterflies (Danaus plexippus): Nectaring in northern Mexico allows recovery from droughts at higher latitudes
Hobson KA, Taylor O, Ramírez MI and others. Conservation physiology, November 2023.
Read the paper Free to read · doi:10.1093/conphys/coad087
What this paper is about
Monarchs live on stored fat through the Mexican winter, and they build those reserves from nectar on the way south. The authors sampled migrating monarchs at 25 locations across three autumns, from southern Canada to the overwintering sites.
Droughts along the route were expected to leave butterflies underweight. Nectaring in northern Mexico let them recover from shortfalls further north.
Summarised here from the abstract below. Not the authors’ words.
Abstract
The eastern population of the North American monarch butterfly (Danaus plexippus) overwinters from November through March in the high-altitude (3000 m+) forests of central Mexico during which time they rely largely on stored lipids. These are acquired during larval development and the conversion of sugars from floral nectar by adults. We sampled fall migrant monarchs from southern Canada through the migratory route to two overwintering sites in 2019 (n = 10 locations), 2020 (n = 8 locations) and 2021 (n = 7 locations). Moderate to extreme droughts along the migratory route were expected to result in low lipid levels in overwintering monarchs but our analysis of lipid levels of monarchs collected at overwintering sites indicated that in all years most had high levels of lipids prior to winter. Clearly, a significant proportion of lipids were consistently acquired in Mexico during the last portion of the migration. Drought conditions in Oklahoma, Texas and northern Mexico in 2019 resulted in the lowest levels of lipid mass and wing loading observed in that year but with higher levels at locations southward in Mexico to the overwintering sites. Compared with 2019, lipid levels increased during the 2020 and 2021 fall migrations but were again higher during the Mexican portion of the migration than for Oklahoma and Texas samples, emphasizing a recovery of lipids as monarchs advanced toward the overwintering locations. In all 3 years, body water was highest during the Canada-USA phase of migration but then declined during the nectar foraging phase in Mexico before recovering again at the overwintering sites. The increase in mass and lipids from those in Texas to the overwintering sites in Mexico indicates that nectar availability in Mexico can compensate for poor conditions experienced further north. Our work emphasizes the need to maintain the floral and therefore nectar resources that fuel both the migration and storage of lipids throughout the entire migratory route.
Abstract reproduced from the published paper, which is licensed CC BY. Copyright remains with the authors.
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"Dynamics of stored lipids in fall migratory monarch butterflies (Danaus plexippus): Nectaring in northern Mexico allows recovery from droughts at higher latitudes (listing)." Milkweed USA, 2026, https://milkweedusa.com/research/dynamics-of-stored-lipids-in-fall-migratory-monarch-butterflies-2023/. Accessed DATE.
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title = {Dynamics of stored lipids in fall migratory monarch butterflies (Danaus plexippus): Nectaring in northern Mexico allows recovery from droughts at higher latitudes (listing)},
author = {{Milkweed USA}},
year = {2026},
url = {https://milkweedusa.com/research/dynamics-of-stored-lipids-in-fall-migratory-monarch-butterflies-2023/},
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