Updated: Jul 8
For Oregon lepidopterists, butterfliers and butterfly photographers, spring is the time to venture into stream and river canyons in southern and eastern Oregon. These canyons are often wickedly hot, brown and dry in mid-summer, but can be flush with green and bursting with wildflowers after spring rains. More water, more flowers, and more green growing plants means more butterflies. On the other hand, a dry spring can cause the vegetation to go into summer dormancy earlier than normal, leaving little nectar resource to sustain butterflies.
This year, the butterfly season in the lower Deschutes River Canyon seems to be hanging on, even though there has been no water in many of the streams in the side canyons for a few weeks. I was surprised to find 27 species over two days under such dry conditions, which is more diversity than I found last year, when there was more water present. Below is a photo from last year, when there was ample water in Jones Canyon at this time of year. This year? Nada.
I surmised that the key to the sustenance of the butterfly season was that there was somehow enough soil moisture to support both host plants and nectar plants, even though it wasn't enough to keep the streams watered. The flight times of several species seemed to be a bit skewed. Sheridan's Hairstreaks are typically more common here in April than in May, yet I saw several on this trip.
While some species seemed to be hanging around later than "normal," other species were notably early, such as the boldly marked Arrowhead Blue below. This May 4 sighting was two weeks earlier than my previous earliest sighting for this species in Oregon.
Even earlier relative to its normal flight period was this greater fritillary, likely a Callippe Fritillary. Andy Warren's "Butterflies of Oregon: Their Taxonomy, Distribution and Biology," cites late May as the early end of the flight period for Callippe Fritillary. So, if this is Callippe, then it was a good three weeks early! For a butterfly that is a pretty radical departure from the norm.
[Update: May 31, 2020. Speyeria expert Paul Hammond clarified that the photo below shows a Coronis Fritillary (Speyeria coronis).]
I find that Jones Canyon and Gert Canyon are generally the most productive sites in the lower Deschutes canyon. Gert Canyon did have a few stretches of stream with water, although it was very much intermittment as I traversed the canyon. As you can see from the photo below, the hillslopes remained a bit green on the north facing side, and the riparian zone was quite green and healthy. Gert Canyon did not burn in the fire that hit Jones Canyon a few years back, and that may be partly why it retains a more native plant community. This could explain at least in part why I saw numerous Common Sootywings in Jones Canyon, and none in Gert Canyon, where I spent more time overall.
Blues were the dominant butterfly group in these canyons on this visit. I encountered large numbers of Acmon Blues, and a smattering of Boisduval's Blues, Melissa Blues, Silvery Blues, one Arrowhead Blue, and a few Columbian blues, like this one, nectaring on what I believe to be Arrow Leaf Buckwheat (Eriogonum compositum var. compositum), its host plant (I admit to being deficient in the skill of ID-ing buckwheats). Rather convenient to have one plant feeding both the larval and adult stages of the butterfly.
The on and off sun during the two days I was there gave me some good photo opportunities. The cloudy periods cooled things off, and caused many species to bask in what filtered sun there was. When the sun would come out, they would continue basking for a few minutes to warm their flight muscles. This fresh female Melissa Blue was very obliging.
This picture-perfect male Pale Crescent couldn't get warm enough with the cloud cover and posed for me like a champ. Note the diagnostic squarish black patch near the trailing edge of the forewing. That field mark and its relatively large size easily distinguish this species from the more widespread Mylitta Crescent.
Happily I encountered only one tick and no rattlesnakes during my visit. Actually, I enjoy finding and watching rattlesnakes, but have a healthy respect for them. As I have on each of my trips this year, I continued to refine my practices to prevent any chance that I could transmit or catch COVID-19 to/from anyone else, traveling self-contained for everything except gasoline. I've learned to buy my gas through the passenger side window to maintain six feet between me and the gas attendant, and to clean my hands and credit card before and after with alcohol spray. I camp far from any gathering spots and I drive more conservatively than normal to minimize the changes of needing emergency services. Rather than leaving trash behind me, I am picking up and disposing of trash left by previous campers. It is very sad to read of the recent closure of state forest lands because disrespectful visitors have been leaving these areas full of trash and human feces when they leave. While I am breaking the stay-at-home rules, I do so with a concerted and thoughtful effort to make sure that I am robustly addressing the goals and objectives of those rules. I hope you do the same if/when you venture out.
My list of species and number of individuals for the two days looked like this: