As I walked through the forest on a warm spring afternoon, I saw a dark creature flutter by. It was a mourning cloak butterfly! As I looked around, I saw more butterflies. A skittish eastern comma was feeding on sap from a sugar maple, while another sunned itself on the ground below the leafless canopy. My first butterfly sightings of 2017!
Every spring I look forward to seeing these colourful insects. I spent nearly two years catching, observing and studying them for my master’s research. It’s difficult not to become partial to butterflies after spending so much time with them
Not only are butterflies beautiful, they are incredibly diverse, with approximately 20,000 species worldwide. More than 100 of these are found in Ontario. Lepidopterists have studied some populations of butterflies for decades, generating data that has informed our understanding of butterfly population dynamics and the impacts of climate change, and helped us focus our conservation efforts.
Some of the first butterflies to watch for in the spring are mourning cloaks, eastern commas and Millbert’s tortoiseshells. The adults of these species hide in the leaf litter during winter, emerging to look for mates in spring when the temperature is warm enough.
Most other butterflies overwinter as eggs, caterpillars or chrysalides, stopping their development until spring. Examples include many hairstreaks that overwinter as eggs, fritillaries that overwinter as caterpillars and charismatic swallowtails that overwinter as chrysalides.
Other species migrate to Ontario from their overwintering grounds farther south. Some are irregular visitors that get blown here by wind, such as pipevine swallowtails and painted ladies. Others, such as red admirals, are more common.
Iconic monarch butterflies migrate to Canada over several generations each spring, and fly nearly 5,000 kilometres back to Mexico each fall. By June, these large orange and black insects can be seen flittering around open meadows, often near patches of milkweed.
Monarch butterflies serve as a stark reminder of the impact human behaviour can have on nature. Population estimates of this species have declined by 50 percent since the 1970s. Habitat loss and climate change are some of their biggest threats.
When you are out this spring, look for early-emerging butterflies and watch as more species appear throughout the summer. Observe them closely and you may be amazed by the diversity and behaviour of these backyard animals.
Jenna Siu completed a masters degree in biology studying the effects of landscape fragmentation on butterflies in southern Ontario. She is a former Ontario Nature Conservation Assistant.