Study
Coldness Triggers Northward Flight in Remigrant Monarch Butterflies
Guerra, Patrick A.; Reppert, Steven M.
Current Biology, 2013
Autumn migrant monarchs were flown in a flight simulator, then exposed to temperatures matching an overwintering site in Mexico for several weeks, then flown again.
- Studied in
- Danaus plexippus
- Sample size
- monarchs tested in a flight simulator before and after cold exposure
Butterflies that had experienced the cold reversed their preferred heading from southward to northward; those held warm continued to orient south.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Cold exposure at the overwintering site is the cue that switches the migratory direction for the spring return, rather than day length or an internal calendar alone.
How NatureHQ reads it
The record that explains how a generational relay stays coordinated without any individual knowing the plan: the direction is not remembered, it is re-set by a condition the animal encounters. It is also a warning about climate — a switch that depends on being cold enough is a switch that can fail.
- Flight-simulator headings, not tracked journeys.
- One population; the eastern North American migration is not the only monarch migration.
Giving a butterfly a Mexican winter, indoors
If no monarch survives to make the whole round trip, what tells the spring generation to fly the other way?
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Monarch butterfly
The butterflies that arrive in Mexico are the great-grandchildren of the ones that left it. No monarch makes the round trip, so none of them can be remembering the way.
Monarch butterfly
What turns a monarch round in spring is having been cold. Butterflies given a Mexican winter in the laboratory flew north afterwards; those kept warm carried on flying south.
Published by: Cell PressPublished in a Cell Press journal.
doi.org/10.1016/j.cub.2013.01.052
Checked against Crossref on 2026-09-28, and they agree on the title, the authors and the year.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-09-03.