Researchers at the University of Guelph surprised even themselves with their findings on where monarch butterflies come from.

Prevailing wisdom in the butterfly world is that most monarchs are born in the midwestern United States, because that is where they leave from for their winter migration to winter.

Instead, the researchers found, only 38 per cent of tracked monarchs come from the American midwest, with the remainder being spread across various parts of the United States and Canada.

The research team says its efforts will help efforts to preserve the population of monarch butterflies, as they provide proof that focusing those efforts on the midwest mean many butterflies get missed.

To come to these findings, the researchers analyzed chemical isotope signatures on the wings of more than 1,000 butterflies, which provide evidence of where the monarchs were born.

Researchers at Environment Canada, the International Atomic Energy Agency, Western University and schools in the United States and Mexico also took part in the project.

The full study can be read in Global Change Biology.

The monarch butterfly population has been in decline in recent years – something a previous Guelph study connected to a parallel decline in milkweed crops.