ArticleInsects2021
First Population Study on Winter Breeding Monarch Butterflies,
Article in Insects, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 9 papers.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
9 citing papers in PubMed.
- Eastern North American Monarch Butterfly Conservation Needs and Opportunities: What the Science Tells Us.Insects · 2026Review
- Phenology and Abundance of Migratory and Breeding Populations of Monarch Butterflies in the Pacific Northwest 2012-2024.Insects · 2025Article
- The impact of temperature on the reproductive development, body condition and mortality of autumn migrating monarch butterflies in the laboratory.Royal Society open science · 2025Article
- The role of a non-native host plant in altering the seasonal dynamics of Danaus plexippus (Lepidoptera: Nymphalidae) development.Journal of insect science (Online) · 2025Article
- Dramatic recent declines in the size of monarch butterfly (Proceedings of the National Academy of Sciences of the United States of America · 2024Article
- Review
- Population genetics of a recent range expansion and subsequent loss of migration in monarch butterflies.Molecular ecology · 2022Article
- Article
- Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
4 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
The western North American monarch butterfly population assessed by counts of non-reproductive overwintering butterflies at coastal sites in California declined to less than 2000 in 2020/21. Simultaneously, reports of reproductive monarchs increased in San Francisco urban areas, perhaps representing a shift in overwintering strategy. To better understand monarch winter breeding in the Bay area, we studied adult and immature populations in Santa Clara County during January-June 2021. Adult monarchs were common with numbers ranging from 0.23-1.54/min during ~30 min weekly surveys at one site, with lowest numbers late April to mid-May. Eggs and larvae, primarily on ornamental milkweeds, were found on nearly all survey dates with lowest numbers mid-late April to mid-May. Levels of infection of adults by the parasite
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.