Advancing conservation: in the field with butterflies October 6, 2025

Imagine you’re going on a long road trip — you can’t forget to get gas or charge your car. Monarch butterflies are similar. To prepare for their almost 5,000 kilometre-long fall migration, monarchs also need fuel. But their fuel is nectar from flowering plants.

I am a graduate student at the University of Ottawa studying how monarch butterflies use habitat, in collaboration with Environment and Climate Change Canada and the Nature Conservancy of Canada (NCC). While I have always been interested in animal ecology, I had never worked with pollinators before. I learned so much about monarchs, their behaviour and their habitat during my time in the field last summer.

The endangered monarch butterfly needs to build fat reserves to power their migration from Canada and the United States to Mexico. An average monarch weighing 0.5 grams — less than a raisin or a paperclip — needs roughly 0.1 grams of body fat (20 per cent of their body weight). They build fat by feeding on the nectar from flowers, especially before their migration starts. Unfortunately, habitat destruction, degradation and fragmentation caused by human activity has negatively impacted the monarch population — the last 20 years have seen an 80 per cent decrease in the eastern North American monarch population. Habitat in southern Ontario, particularly around the Great Lakes, is their core breeding range in Canada; without it, monarchs would struggle to reproduce and build enough fat reserves to power their migration.

That’s why NCC’s work is so important. Over the last 20 years, NCC has restored native habitat on former agricultural fields and modified lands in Norfolk County, in southern Ontario. This included planting native wildflowers needed by monarchs, like brown-eyed Susan and wild bergamot, along with milkweed, the only plant on which monarchs can lay their eggs. All that conservation work set the stage for our research.

We want to know if certain aspects of these restored sites make them particularly attractive to monarch butterflies, like the size of the site or the amount of flowers and milkweed present, and how long the monarchs stayed in a restored site. We also wonder where monarchs go after they leave these sites on their southward migration: do they funnel along the Lake Erie shoreline or fly directly across the lake? These kinds of questions help to test and guide conservation, including how and where to protect and restore monarch habitat for the biggest impact.

To answer our first question, I spent last summer doing field surveys in Norfolk County. I used standardized surveys to observe monarchs feeding from flowers and meticulously identified and counted thousands of flowers and milkweed stems. We saw monarchs in every site we surveyed, which was encouraging. This was my favourite summer job: standing in fields of flowers watching butterflies!

To see how long monarchs stay within one habitat patch, we tagged them with exciting new BluMorpho Bluetooth tags. These tags weigh only 0.06 grams (less than a grain of rice) and are attached between the monarch’s wings. This is brand new technology, and we are some of the only people using these tags in Canada. Unfortunately, the tagged monarchs moved away from our study sites much faster than we anticipated, making it hard to track their local movements. But that was not the end of the Bluetooth tags.  

We also tried using these tags to help us answer our second question about whether monarchs fly around or directly across Lake Erie during migration. We attached BluMorpho Bluetooth tags to 39 monarchs at the tip of Long Point. These monarchs were netted as they flew over or stopped to feed from flowers there. Two nearby monitoring towers were supposed to automatically detect butterflies flying past, helping us to map their movement. Unfortunately, one of the towers malfunctioned, limiting the amount of information we could collect. This is a true representation of field research! It does not always work out the way you expect and learning how to adapt is crucial.

We are going to Long Point again this fall to tag more monarchs. This time, we are taking extra precautions to ensure equipment functions properly. We have also set up four more monitoring towers with our partners Birds Canada, so we can detect which direction the monarchs are flying more precisely and over a larger area.

A lot of effort goes into protecting monarchs across North America. I’ve spent the last year studying how monarch habitat should be restored, and over the next year I’ll be evaluating where restoration should take place. These butterflies connect us across the distance of their migration, even 5,000 kilometres away. Next time you see a monarch feeding from a flower, I hope you will think about the importance of habitat restoration and the ecological value of small and large habitat patches. Every bit makes a difference!