Discovery Islands Lepidoptera
Published in the December 14, 2018 edition of the Discovery Islander:
Butterflies of the Discovery Islands
By Lunabelle Loiseau Tremblay
THIS SUMMER, I decided to document the butterfly species on Quadra, because whenever I have looked in the identification guides, I have noticed that local records for the area are sparse. This gives the inaccurate impression that we don’t have many butterfly species here. British Columbia has 187-192 species of butterflies, which is more than any other province or territory in Canada. When using the term butterfly, I am referring to true butterflies in the superfamily Papilionoidea and another large group called skippers, which are in the superfamily Hesperioidea, both belonging in the order Lepidoptera (moths and butterflies). (Guppy and Shepard, 2001)
Butterflies are important because they are pollinating insects, but also because they contribute to the biological diversity of our area. Biological diversity itself is under attack and it is important that we do what we can to preserve what we have left before we find our gardens and ecosystems void of the wonders of nature.
It is evident by now that insect numbers have dramatically decreased in recent years. Habitat destruction from increased housing and property development, industrial sites, roads, recreational sites, farmland, invasive plants (ie. Scotch Broom), fire suppression, non-native butterfly species (ie. Cabbage White), pesticides and biological control agents are just a few of the contributing factors leading to this noticeable decline. Although there is steady speculation as to whether the effects of logging and mining are detrimental to butterfly populations, from what I have read and seen firsthand, the evidence is uncertain. As much as I am not on the side of industrial logging, in my experience older clear cuts are amazing areas to find butterflies because of how flowering weeds colonize the new areas and open areas up to meadow type ecosystems. Climate change is also something to consider. It’s very possible that we will start seeing the disappearance of some species while other species from further south start to move in.
I started documenting species in April 2018 and continued to record my findings through October when the rains started. The first butterfly I saw this year was the Western Spring Azure and the last one I saw was a Cabbage White on December 5th! Last year, a friend sent me a picture of a Red Admiral in her garden on October 28th 2017. The Red Admiral and the Mourning Cloak are two species that hibernate as adults until the following spring when they can actually be flying at the same time as their offspring. I documented 25 species in total on Quadra, however, commonly we see a 26th, the migrating Painted Lady, but none were seen this year.
Here’s the list of species seen during the 2018 season on Quadra:
Western Spring Azure, Sara’s Orangetip, Western Tailed Blue, Mourning Cloak, Western Elfin, Hydaspe Fritillary, Pale Swallowtail, Pacific Fritillary, Western Swallowtail, Lorquin’s Admiral, Anise Swallowtail, Purplish Copper, Cedar Hairstreak, Mylitta Crescent, Grey Hairstreak, Common Wood-nymph, Red Admiral, Cabbage White, Milbert’s Tortoiseshell, Pine White, Satryr Anglewing, Great Arctic, Two Banded Checkered Skipper, Woodland Skipper, and Western Branded Skipper.
All observations were either single or repeated observations and photographic evidence was taken for all except three species that were hard to photograph. Some of these species are subspecies and surprisingly on Quadra, we have two species which are red-listed, which identifies them as extinct, endangered or threatened on the IUCN list for threatened species. These two species are the Common Wood-nymph (Cercyonis pegala ssp. incana) and the Western Branded Skipper (Hesperia colorado oregonia). Although I have known for many years of the subspecies of Common Wood-nymph, the Western Branded Skipper was a complete surprise to me, as it was to the lepidopterist that I emailed to confirm my observations. I also got in touch with the BC Conservation Data Centre and was put in contact with a zoologist who has studied the more well known population of these skippers around Cordova Shore, BC.
In fact, the population here on Quadra is in a very different kind of environment than the population down south. The Common Woodnymph can be found in many places on the island, flying in late July and August. It is a medium sized butterfly, dark to light brown with two large well defined eye spots on the forewings, and often with an eyespot(s) on the hindwing. The Western Branded Skipper (also known as the Oregon Branded Skipper) is a small skipper (2.7-3cm) an orangish-brown base colour with white-silverish spots on the wings. Although at first glance it can easily be mistaken for the very common Woodland Skipper, it is easily distinguishable from it when looked at closely. In fact, this skipper is the subject of debate among entomologists and lepidopterists regarding nomenclature and speciation. In any case, I have looked in many places on the island and only found it in one place, in a marsh on Crown land. I am thankful that the place I found it is not frequented by humans but it is very close to a high traffic road. There were also observations of it on Cortes Island around the same date of my observations on Quadra. Incredibly, Cortes is home to the 2017 observation of the Silver-spotted Skipper (Epargyreus clarus) which had not been seen in this area for 110 years. I would be very interested to know what species there are in the less occupied Outer Islands.
Butterflies are small and may not seem as significant as the Orca and Salmon but in fact, they are also an integral part of our ecosystem. I wrote this article to draw attention to the small things of importance we have on this beautiful island. This is one of the ways I can give back to my community that raised me into the person I am today. —Lunabelle Loisseau Tremblay