By Jeff SkevingtonSingle-day insect surveys are nerve-wracking as they are controlled to a great extent by the weather. It was thus a pleasure to awake on July 5 to spectacular weather for the 14th annual OFNC butterfly count. Butterflies like the sun, but shut down if it gets too hot. The day was perfect with a high of 27 degrees and no cloud. Thirty observers were in the field for the count this year and were treated to one of the best days out in recent memory.
Butterfly counts, like Christmas Bird Counts, are established around a standard count circle 24 km in diameter. Surveying hundreds of circles across North America every year allows for comparison of butterfly numbers and may provide insight into the health of our environment. Counts are coordinated by the North American Butterfly Association. Our circle is centred on Manion Corners west of Stittsville. Participants are divided among experienced group leaders. This year we had five groups in the field covering the circle and had some great highlights.
We rarely add new species that we have never seen before, but this year was exceptional with three additions! Peter Hall and his group found a Mulberry Wing at the south end of Beavertail Road (photo below left). This species is rare and local in the Ottawa area, mostly because its wet sedge meadow habitat is disappearing with development.
A second new species found this year, Two-spotted Skipper (below right), is also a wet sedge meadow specialist that is rare and local in our region. Our group found one in the wet meadow just south of our meeting area at the intersection of Dwyer Hill and March Roads and another in a wet meadow in Burnt Lands Provincial Park.
The other new find for the count was Giant Swallowtail. This species has been marching northward with climate warming and is already common in Ottawa despite just showing up here three years ago. Their larvae feed on Prickly Ash and our adult was seen on Burnt Lands Road in an area with lots of the host plant.
In addition to the three new species, we also set new high count records for six species: Eastern Tiger Swallowtail (8), Mustard White (109), Banded Hairstreak (17), Summer Azure (165), Eastern Comma (17), and White Admiral (64).
Count results are online on the OFNC website. Thanks to everyone who participated!