Butterflying with an Expert at Bristow Prairie

Neil Bjorklund at the rock garden all geared up for a day of butterfly photography.

One of the odd cat’s ears (Calochortus sp.) I’ve seen so often at Bristow Prairie. Not only does it have two extra petals, it’s not clear which species it is.

It had been almost 20 years since I’d had the opportunity to go out in the field with butterfly expert Neil Bjorklund. Neil’s website Butterflies of Oregon is the resource for the butterflies of our state, and he was a co-founder of our local chapter of the North American Butterfly Association (NABA). On June 28, we headed up to Bristow Prairie, one of my all-time favorite spots. Neil had been to Bristow Prairie a number of times, but he hadn’t been to the small wetlands that—as far as we know at present—are the northernmost outposts of Sierra Nevada blues. He also wasn’t aware of the south-facing bald I call “the rock garden” or “Lewisia Point,” two other excellent places to see butterflies. Our trip was mutually beneficial—I showed him my favorite spots, and he taught me a lot more about identifying butterflies.

Wet areas of the main meadow were filled with straightbeak buttercup (Ranunculus orthocarpus).

My favorite Sierra Nevada blues nectaring on their favorite flower, bistort (Bistorta bistortoides). The male on the left is gray, while the female, on the right, is a warmer brown.

I was relieved that we saw several male Sierra Nevada blues when we started out in the small wetland at the north end of the main meadow. We had both been concerned it might still be too early for them after the heavy winter snowpack. They seem to appear as their host food plant, mountain shooting star (Dodecatheon jeffreyi) is starting to fade. From the freshness of the butterflies, we probably got there at the beginning of their season. We found even more Sierra Nevada blues at the wetland on the west side of the ridge—the Umpqua National Forest side but still in Lane County. There were more females there as well.

We climbed up to the top of the rock garden. There were not as many butterflies as I sometimes see there, but we did see mating pairs of blues and duskywings, and Neil showed me how to tell the difference between dotted blues (Euphilotes enoptes) and the more recently named glaucon or summit blues (E. glaucon). The flowers were beautiful as always in July, even though it was drier than usual for this time of year.

While the day was mostly sunny, a few clouds had formed overhead as we returned across the rock garden. On the way north, I had photographed the abundant whisker brush (Leptsiphon ciliatus) in bright sun. I stopped on the way back and took another photo under some clouds. There had been clouds off and on for only maybe half an hour, but that was enough to cause the flowers to close up. Thankfully, it cleared up again so we could keep watching butterflies.

Summit blues can be distinguished from the similar dotted blue by their heavier black markings and the more continuous orange band on the ventral hindwing, especially on the female, like this one. Sulphur buckwheat (Eriogonum umbellatum) is its host food plant as well as a favorite nectar plant. The dotted blue uses northern buckwheat (E. compositum). Both buckwheats were blooming in the rock garden, and both species of blues were there as well. That certainly makes it a lot easier to compare them!

For comparison, here is a mating pair of dotted blues (female on the right) perched on sticky cinquefoil (Drymocallis glandulosa).

On the slope of the rock garden, we spotted a western branded skipper chasing a moth around. At first, I thought it was just territorial behavior, but then it became apparent the skipper was actually following the moth around because he was trying to mate with it! I have seen this strange behavior twice before with butterflies attracted to sheep moths. Neil said he’d seen it too. Here they landed briefly on sulphur buckwheat.

Thankfully this spring white landed on the reflexed rock cress (Boechera retrofracta) just long enough for me to get this shot so I could see what it looks like in detail. I also saw a few eggs and a couple of caterpillars on the rock cress nearby; most likely these were spring whites as well. Most whites use mustard family species for their host plants.

We finished off our day by heading out to Lewisia Point. An adult white landed on the rock cresses that I always check for eggs and caterpillars. Suddenly, Neil exclaimed excitedly that there were in fact spring whites (Pontia sisymbrii) there. He’d heard from fellow NABA member Lori Humphreys that they were in the area but was surprised to actually see them. Their reported range just dips into southeastern Lane County from the east. Not being as focused on butterflies as I am on plants, I didn’t know anything about spring whites, so I’d been lazily calling all the similar high-elevation whites western whites (P. occidentalis). Spring whites are similar to western whites, but as Neil pointed out to me, the markings on the outer forewings are darker bars rather than gray triangles, the bar at the end of the forewing cell is solid, and the veining is more prominent. I had found a caterpillar elsewhere in the Calapooyas 10 years ago that looked more like the photos of spring whites, so it made sense now that their range does reach into this area. The next day, I checked my old butterfly photos and discovered many of my “western white” photos in the Calapooyas, (including some at this same location, see Still More Discoveries at Bristow Prairie) were actually spring whites. Learn something new every day!

It’s hard to tell the caterpillar of a spring white from a western white at this stage. I wonder what the fly is doing sitting on the caterpillar. I’ve seen ant-tending in the caterpillars of blues, but fly-tending? Maybe it was finding something to lick off on the end of the long hairs.

Here’s an odd combination: Alaska cedar (Callitropsis nootkatensis) and Oregon white oak (Quercus garryana) side by side. Growing on top of this rocky ridge, the oaks are barely a few feet tall.

While I looked at the last blooming Columbia lewisia (Lewisia columbiana), Neil was chasing a large duskywing. The largest of our duskywings is the propertius, but they use oaks as their host food plant, so thinking they were no oaks anywhere nearby, we were a bit puzzled. But as we headed back to the road, I noticed there were in fact oaks here, they were just so short that we hadn’t noticed them. Puzzle solved. We went over some of the many species of butterflies we had seen during the day. Neil mentioned we hadn’t seen a brown elfin. Apparently, he also has my “superpower” to conjure up wishes (see Yet Another Exciting Discovery at Bristow Prairie for my first discovery of Lewisia Point when I made both a butterfly and a plant magically appear) because suddenly a brown elfin appeared! A perfect way to wrap up a great day. Thanks to Neil for helping me sort out some of these look-alike butterflies. Guess I’d better update my gallery now!

A dozen or more tiger moths were happily nectaring on some phacelia by the roadside. While not uncommon, I don’t think I’ve ever seen so many in one spot.

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