Monarch butterflies have a one-track migratory mind. Like a bumbling sit-com dad leading a family vacation to Mexico, the insects just head southwest for thousands of miles and don't stop for directions.
Neuroscientists recently documented that the monarch butterflies of eastern North America don't use fancy navigational strategies; they just fly with a general southwest orientation until they reach the forests in the mountains west of Mexico City. Luckily for the butterflies, the geography of North America funnels them into Mexico.
Thus, the insects complete their massive migration although no living butterfly ever completes the entire migration to Mexico and back. The instinct to fly to the southwest seems to be the main strategy the monarchs pass on to the next generation to enable their epic migration that starts as far away as New England and Canada for some monarchs.
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To test the monarch's migratory strategy, a team of scientists captured butterflies in Alberta, Canada and measured their flight trajectory. The same butterflies were then transported 2,500 kilometers west to Ontario. In both locations the butterflies tended to fly southwest. If the butterflies were using a complex navigational technique they would have adjusted course in Alberta and flown to the south.