Midsummer Meadows: Pollinator Monitoring at Princess Point

By Mallory Peirce, Senior Terrestrial Ecologist, Royal Botanical Gardens

In the heat of a Southern Ontario summer, meadows become a daydream filled with vivid colour. The generous sun pours honeyed light over native grasses swaying in a gentle breeze. Black-eyed Susans, Wild Bergamot, and Milkweed add pops of colour to the lush green background. Dragonflies skim the air, with their wings catching the light like stained glass in motion. The sound of crickets and summer birdsong fill the air. A Monarch floats by displaying its orange-fired wings. This is summer in RBG’s meadows.

After a successful controlled burn this spring at Princess Point, RBG’s ecologists and volunteers alike were eager to see how the butterfly community responded to the burn. Armed with a butterfly net and an identification guide, these enthusiasts aim to observe as many butterflies as possible during the count. Butterfly species’ presence, or absence, are very sensitive indicators of ecosystem health. Minor changes in climate, food availability, and habitat can drastically impact population levels. Therefore, long-term butterfly monitoring programs help identify broader habitat changes. Many culprits of habitat change can be linked to Climate Change, large-scale pesticide use, and most impactfully, large-scale habitat loss.

Thanks to the help of volunteers and staff, 21 native species and 319 butterflies were observed at three native grassland sites at RBG during the 2025 count. The most common native butterflies seen on the count were Common Wood Nymph, Monarch, Clouded Sulphur, Silver-spotted Skipper, and Black Swallowtail. Overall, native butterfly numbers at RBG have been steadily declining since observations experienced continued growth and peaked in 2023. Balanced wildlife populations exhibit booms and busts, but further monitoring and continued conservation efforts are needed to determine whether butterflies at RBG are experiencing a natural decline, or if numbers start to dip to concerning levels.

One factor that could have impacted the number of butterflies seen this year is the cool and damp spring we experienced. Caterpillar development requires warm conditions to complete their lifecycle, and therefore, having delayed warm temperatures in the spring, butterfly development may have occurred later than in years past. Further monitoring efforts are required to determine if the late arrival of warm spring weather in 2025 was the culprit for relatively low observations.

Arguably one of the most iconic and beloved insects in North America is the migratory Monarch Butterfly, who spends their summer in meadows dotted with milkweed plants. An international superstar, the Monarch is a powerful symbol for pollinator conservation and habitat protection. RBG’s conservation efforts strongly enhance appropriate habitat requirements for Monarch butterflies, with many observed during annual butterfly counts! Since 2018, Monarch observations during the count have remained steady, until 2024. As with overall butterfly trends mentioned previously, Monarch observations have decreased from 79 in 2023 to 41 in 2025 (the lowest number since 2017). Could the Monarch be sounding the alarm? Only time will tell. In the meantime, RBG will continue to protect, enhance, and improve grassland ecosystems for butterflies through prescribed burns, invasive species removal, and planting native species.

Treat yourself to a summer and early fall wander at Princess Point, and you will experience the joy of hearing the gentle buzz of pollinators and vibrant colours of native wildflowers. Every step through Princess Point is a reminder of the resilience of nature and the importance of conservation. A place to slow down, listen, and reconnect with the rhythms of summer pollination.

How can you support butterfly conservation in your backyard?

1. Remove invasive species that out-compete native plants, such as Dog-strangling Vine.
2. Plant native milkweed species, such as Butterfly Milkweed (pictured above). Milkweed species are the only plants that Monarch caterpillars eat.
3. Provide nectar plants for adults, which gives them energy throughout their migration. Examples include Black-eyed Susan, Coneflower, Wild Bergamot, and Goldenrod species.
4. Avoid using pesticides and herbicides, as these chemicals can harm Monarchs, their eggs, and food sources.