Version 1
: Received: 23 May 2024 / Approved: 24 May 2024 / Online: 24 May 2024 (14:04:14 CEST)
How to cite:
Davis, A.; Croy, J.; Snyder, W. Dramatic Recent Declines in the Size of Monarch Butterfly (Danaus plexippus) Roosts During Fall Migration. Preprints2024, 2024051630. https://doi.org/10.20944/preprints202405.1630.v1
Davis, A.; Croy, J.; Snyder, W. Dramatic Recent Declines in the Size of Monarch Butterfly (Danaus plexippus) Roosts During Fall Migration. Preprints 2024, 2024051630. https://doi.org/10.20944/preprints202405.1630.v1
Davis, A.; Croy, J.; Snyder, W. Dramatic Recent Declines in the Size of Monarch Butterfly (Danaus plexippus) Roosts During Fall Migration. Preprints2024, 2024051630. https://doi.org/10.20944/preprints202405.1630.v1
APA Style
Davis, A., Croy, J., & Snyder, W. (2024). Dramatic Recent Declines in the Size of Monarch Butterfly (Danaus plexippus) Roosts During Fall Migration. Preprints. https://doi.org/10.20944/preprints202405.1630.v1
Chicago/Turabian Style
Davis, A., Jordan Croy and William Snyder. 2024 "Dramatic Recent Declines in the Size of Monarch Butterfly (Danaus plexippus) Roosts During Fall Migration" Preprints. https://doi.org/10.20944/preprints202405.1630.v1
Abstract
The conservation status of monarch butterflies in North America is a topic of intense scrutiny and debate. It is clear that winter colonies in Mexico are declining, yet some recent studies suggest that summer breeding populations are relatively stable and similar to historical abundances. One possible explanation for these discordant patterns is that fall migration success has been recently disrupted. Here, we use a relatively unexplored citizen-scientist dataset on the size of monarch “roosts,” which are resting aggregations on vegetation, to infer changes in monarch abundance along the fall migration route over the last 17 years. We found that the timing of migration remained relatively unchanged while the flyway has generally become warmer and greener. Warmer and greener conditions were associated with larger roosts, yet we found steady, dramatic declines in roost sizes through time that were independent of climate and landscape factors. Roost sizes have declined as much as 80%, with losses increasing from north to south along the migration route. These findings suggest that failure during the fall migration could explain the apparent drop in monarch numbers from summer breeding to overwintering populations. This in turn suggests that conservation efforts that support fall migration success are most needed, such as limiting the planting of non-native milkweeds that enhance parasite loads and perhaps dampen migration success. Overall, it appears the fall migration of monarch butterflies is under imminent threat, even if the species’ overall survival is not.
Keywords
conservation biology; insect decline; climate change; citizen science; endangered species
Subject
Biology and Life Sciences, Insect Science
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
