The Preponderance of Evidence Indicates That the Eastern North American Monarch Population Has Declined in All Stages of Its Annual Cycle. Reply to Davis, A.K. Comment on "Oberhauser, K.S. Eastern North American Monarch Butterfly Conservation Needs and Opportunities: What the Science Tells Us. Insects 2026, 17, 235"
Oberhauser KS, Pleasants J. Insects, July 2026.
Read the paper Free to read · doi:10.3390/insects17070713
What this paper is about
The second half of a published exchange. Oberhauser and colleagues reply to Davis, who had argued that eastern monarch numbers in summer have not fallen despite the collapse in the area they occupy in Mexico each winter, and that the winter decline is explained by migration mortality and density dependence the following spring.
The reply argues that the weight of evidence points to decline at every stage of the annual cycle, and addresses the concern that conservation funding might be steered toward a species that does not need it.
Summarised here from the abstract below. Not the authors’ words.
Abstract
Davis critiqued a recent review, "Eastern North American Monarch Butterfly Conservation Needs and Opportunities: What the Science Tells Us". He argued that Eastern North American monarch numbers in the summer have not declined, despite dramatic declines in the area covered by this population in Mexico during the winter. These declines in winter numbers, he said, can be explained by increasing mortality during the fall migration and subsequent density-dependent increases the following spring. A strong impetus for these arguments appears to be Davis's concern that recommendations by "certain circles" of the monarch research community could steer conservation funding toward a species that does not need our help. Here, we address these concerns, and note that there is no evidence that conservation funding focused on providing breeding habitat for monarchs detracts from conservation for other species in need of help, or from efforts to support migrating monarchs.
Abstract reproduced from the published paper, which is licensed CC BY. Copyright remains with the authors.
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Milkweed USA. (2026). The Preponderance of Evidence Indicates That the Eastern North American Monarch Population Has Declined in All Stages of Its Annual Cycle. Reply to Davis, A.K. Comment on Oberhauser, K.S. Eastern North American Monarch Butterfly Conservation Needs and Opportunities: What the Science Tells Us. Insects 2026, 17, 235 (listing). Retrieved DATE, from https://milkweedusa.com/research/the-preponderance-of-evidence-indicates-that-the-eastern-north-2026/
"The Preponderance of Evidence Indicates That the Eastern North American Monarch Population Has Declined in All Stages of Its Annual Cycle. Reply to Davis, A.K. Comment on Oberhauser, K.S. Eastern North American Monarch Butterfly Conservation Needs and Opportunities: What the Science Tells Us. Insects 2026, 17, 235 (listing)." Milkweed USA, 2026, https://milkweedusa.com/research/the-preponderance-of-evidence-indicates-that-the-eastern-north-2026/. Accessed DATE.
Milkweed USA. "The Preponderance of Evidence Indicates That the Eastern North American Monarch Population Has Declined in All Stages of Its Annual Cycle. Reply to Davis, A.K. Comment on Oberhauser, K.S. Eastern North American Monarch Butterfly Conservation Needs and Opportunities: What the Science Tells Us. Insects 2026, 17, 235 (listing)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/research/the-preponderance-of-evidence-indicates-that-the-eastern-north-2026/.
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