A break from the butterflies
Posted onAugust 15, 2023by|, ,
A break from the butterflies?
This is not a choice made by our field crew at Pinery Provincial Park, yet one the mottled duskywings make for us. Unlike the majority of duskywing species in Ontario, mottled duskywing has two flight periods each year at Pinery. In May, the overwintering larvae will pupate and eclose, meaning they emerge into their beautiful adult stage and spend the next couple weeks mating. By the end of June most adults finish flying and their caterpillar (larvae) offspring are busy at work, filling up on New Jersey Tea leaves, to get big and strong for their next life stage, pupae! Unlike their parents these larvae won’t overwinter, they will form pupae. This generation will start enclosing in mid July to form the second generation of butterflies this year. That means that we have between 2-3 weeks without butterflies! So, what do we do in the meantime? Holiday! Just kidding, we’ve got some investigating to do.
There’s still much to learn about the mottled duskywing, such as their specific habitat requirements within the park.
We know mottled duskywings love dry sandy areas that are sparse in vegetation and have New Jersey Tea, however we want to know the specifics of what creates the perfect home for our flying friends. This will allow us to understand why some of our reintroduction sites have been more successful than others. Over these past few weeks our focus has shifted to exploring these habitat parameters. Our goal is to create a map that includes a layer of canopy cover, New Jersey Tea, and duskywing sightings so we can compare each layer to create the guidelines of ideal habitat!
A beautiful patch of New Jersey tea in full bloom. It is bigger than a meter squared therefore we mapped it out as a polygon.
An example of how the spherical densitometer displays the canopy cover above.
One of the most important features of a reintroduction site is the abundance of host plants. At Pinery, New Jersey tea is the mottled duskywings’ host plant, meaning females will lay their eggs on this native plant and when they are caterpillars they feed on its leaves. One of our goals in between flight periods is to map each New Jersey tea plant in our sites. Phew! Sounds like a lot of work. Thanks to the help of our handy GPS device, it makes keeping track of each data point much more efficient. For each plant that takes up less than a meter squared we map them as a single point and plants/patches of New Jersey tea that are bigger than one meter squared we record them as polygons.
There’s something we all have in common with the mottled duskywing and its host plant, we all need some sunshine! But how much is too much? It is time we grab our investigating caps and our magnifying glass, however in our case it is a small device called a spherical convex densitometer. This unique instrument displays a 24 square grid on a convex mirror. This allows us to calculate average density of canopy cover, by counting the corners of each square filled in by overstory.
Although our focus has been directed to habitat surveying, the hunt for butterflies hasn’t stopped completely. As we anticipate the second flight period to start soon, we are keeping our eyes open for our butterfly friends. The transition from habitat surveying, back to butterfly monitoring is soon upon us!
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