Growing up in southern Ontario as a butterfly enthusiast, I was always happy to see Red Admirals with their unmistakable red stripes across their forewings.
My life-long friend Rob West, who grew up with me in southern Ontario, sent me one of his terse but welcome email messages recently, with an attached photo.
The subject line read “Butterfly in southern Ireland near Cork,” and the one-word message read “Identification.”
As well as identifying it for him, I told him his photo was of a well-known Canadian butterfly.
I also mentioned I had just seen one myself, here in Aldergrove Regional Park.
What followed was a wild butterfly chase for me through the literature on Red Admirals.
It turns out that they are found throughout much of the northern hemisphere and exhibit a fascinating migratory life cycle.
Unlike many butterflies that overwinter in the chrysalis stage, they hibernate as adults and are unable to do so in the northern parts of their ranges.
In spring, the adults emerge from their hibernating spots, and many fly north to re-populate northern areas.
The one I found in Aldergrove was newly hatched, so I figure its mother must have flown north and laid her eggs on local stinging nettle where the caterpillar completed its life cycle.
A big question is, what happens next if a Red Admiral butterfly is unable to overwinter in its northern range?
A huge clue was published in the European Journal of Entomology in 2003 by Kauri Mikkola, at the Finnish Museum of Natural History.
A group of ornithologists (bird biologists) were convinced to switch to butterflies in 1998 from the Fastholma bird tower strategically located on the northern coast of Finland.
What the ornithologists witnessed was spellbinding.
Many Red Admirals passed the tower high above the forest – 1,240 in September 1998 alone in fact, mostly heading north, but when the winds switched direction, some flew south.
Mikkola was also able to track down even higher-flying Red Admirals via the meteorological radar at the University of Helsinki – they were flying at altitudes of up to 2000 metres!
This also helps explain why Red Admirals are such cosmopolitan butterflies.
In fact, there are closely related species in Hawaii and New Zealand that probably got there on a wing and prayer – sometime in the distant past before evolving into a new species.
This research on Red Admirals gave suggested that both the Red Admirals both Rob and I had spotted might well take to the upper atmosphere and head south to form part of the 2026 generation.
Incidentally, Red Admirals are not overly common here in British Columbia, so keep your eyes open to see one of these amazing globe-trotters visiting your neighbourhood.
– PhD, is a professor of biology and environmental studies at Trinity Western University
