Further Insights on the Migration Biology of Monarch Butterflies, Danaus plexippus (Lepidoptera: Nymphalidae) from the Pacific Northwest
James DG, Kappen L. Insects, February 2021.
Read the paper Free to read · doi:10.3390/insects12020161
What this paper is about
14,040 captive-reared and 450 wild monarchs were tagged in the Pacific Northwest over three autumns. 122 were recovered.
They averaged 900 km from Washington and 630 km from Oregon, with the longest recovery at 1,392 km, travelling about 21 km a day and up to 46 km on the best days.
Summarised here from the abstract below. Not the authors’ words.
Abstract
The fall migration of monarch butterflies, Danaus plexippus (L.), in the Pacific Northwest was studied during 2017-2019 by tagging 14,040 captive-reared and 450 wild monarchs. One hundred and twenty-two captive-reared monarchs (0.87%) were recovered at distances averaging 899.9 ± 98.6 km for Washington-released and 630.5 ± 19.9 km for Oregon-released monarchs. The greatest straight-line release to recovery distance was 1392.1 km. A mean travel rate of 20.7 ± 2.2 km/day and maximum travel of 46.1 km/day were recorded. Recovery rates were greater for Oregon-released monarchs (0.92%) than Washington-released (0.34%) or Idaho-released monarchs (0.30%). Most monarchs (106/122) were recovered SSW-S-SSE in California, with 82 at 18 coastal overwintering sites. Two migrants from Oregon were recovered just weeks after release ovipositing in Santa Barbara and Palo Alto, CA. Two migrants released in central Washington recovered up to 360.0 km to the SE, and recoveries from Idaho releases to the S and SE suggests that some Pacific Northwest migrants fly to an alternative overwintering destination. Monarchs released in southern Oregon into smoky, poor quality air appeared to be as successful at reaching overwintering sites and apparently lived just as long as monarchs released into non-smoky, good quality air. Migration and lifespan for monarchs infected with the protozoan parasite, Ophryocystis elektroscirrha (McLaughlin and Myers), appeared to be similar to the migration and survival of uninfected monarchs, although data are limited. Our data improve our understanding of western monarch migration, serving as a basis for further studies and providing information for conservation planning.
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"Further Insights on the Migration Biology of Monarch Butterflies, Danaus plexippus (Lepidoptera: Nymphalidae) from the Pacific Northwest (listing)." Milkweed USA, 2026, https://milkweedusa.com/research/further-insights-on-the-migration-biology-of-monarch-butterflies-2021/. Accessed DATE.
Milkweed USA. "Further Insights on the Migration Biology of Monarch Butterflies, Danaus plexippus (Lepidoptera: Nymphalidae) from the Pacific Northwest (listing)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/research/further-insights-on-the-migration-biology-of-monarch-butterflies-2021/.
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title = {Further Insights on the Migration Biology of Monarch Butterflies, Danaus plexippus (Lepidoptera: Nymphalidae) from the Pacific Northwest (listing)},
author = {{Milkweed USA}},
year = {2026},
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