The hypothesis I am working to substantiate through this study is that Oak Hairstreaks appear more rare than they actually are due to their elusive canopy-dwelling habits. From my encounters with the species so far, I find this theory to be believable – larvae have been relatively common and the adults that I have seen were quick to dash away into the treetops. Most of the Satyrium favonius ontario observations at Great Blue Hill that I am aware of have been made only where they can be – at flowers when the butterflies descend from their oak perches to nectar. To test the theory that this species spends most of its time out-of-sight of most butterfly watchers requires a heightened vantage point. Today, we brought in the necessary equipment to achieve this – a bucket truck!
An early morning Banded Hairstreak (Satyrium calanus) on a dewy grass blade.
Fueled by a boyish excitement to operate heavy machinery, I arrived very early. As I waited for the bucket truck I searched around the dew-covered flowers and oak branches for butterflies. As things started to dry in the morning sun, I saw a couple Bandeds and one Edwards’ hairstreak. I also came face to face with an animal I’ve never seen before. As I was photographing a butterfly, I heard the grass rustle nearby. I turned to see the vegetation jostle as something covertly approached. The movement of the grass stopped suddenly, and a little furry head popped up out of the undergrowth. It was a weasel of some sort, either an Ermine (Mustela erminea) or a Least Weasel (Mustela nivalis), and it seemed confused to have encountered me. I snapped one good photograph before it turned to take refuge in a derelict pipe behind the utility building.
A weasel (Mustela sp.) who was perplexed to encounter a human on its morning stroll.
The bucket truck arrived around 9AM and after a bit of safety training, I was up above the treetops overlooking all of Great Blue Hill and much of Norfolk County. For the sake of space, logistics, and courtesy to trail users, the truck was parked in the gravel lot across the access road from the observatory. This also allowed me to overlook an area where I had collected at least one Oak Hairstreak prepupa. From the bucket I could clearly see how much Red Oak (Quercus rubra) dominates the landscape. I was armed with my camera, a good pair of binoculars and my field notebook and I was hell-bent on seeing Oak Hairstreaks flitting about the canopy. What I didn’t plan for was the wind…
Billy the bucket truck driver. We positioned over the most accessible area of trees where I haven collected Oak Hairstreak prepupae.
It was a clear day and I had a good view of Boston off in the distance. I was probably the highest point in Norfolk County for an hour.
You don’t usually see the trees like from this vantage point. This was likely from the highest position of the bucket.
Although it was a mild sunny day below the trees, once I rose above them, the wind became problematic. It was very difficult to focus on any patch of leaves with the binoculars or camera before the breeze violently whipped them about. I was able to focus on a few bees that landed on leaves within 15ft of the bucket, but more distant trees were impossible to zoom in on for more than a few seconds.
The effort was not in vain though! Along with a few high-flying Tiger Swallowtail (Papilio glaucus) and Pine Warbler (Setophaga pinus) sightings, I did see hairstreaks. My most promising observation was of two hairstreaks flitting about the top of a pine tree that was higher than the surrounding oaks. They did not seem to be fighting and continued to land in close proximity to each other. Because of the tree they were on I initially thought they were Pine Elfins (Callophrys niphon), but I later realized it is very late in their flight period (mainly mid-April to early June). These may have been two Oak Hairstreaks mating in the high canopy, but I can’t say for certain since they were too far away to identify.
Kevin positioning himself over the oaks.
I stayed up in the bucket for about an hour before switching out with a fellow lab mate, Kevin, who came up today to assist. He also saw a couple hairstreaks in the canopy, but the wind and the distance did not allow for species IDs. The two of us enjoyed our rare view of GBH, but we did not collect any verifiable evidence of Oak Hairstreaks on the turbulent treetops. Even though today was not exceptionally windy and our binoculars are not too shabby, the bucket truck observation method may prove more fruitful on a calmer day with more powerful equipment.
A Pine Warbler (Setophaga pinus) singing merrily from its perch far above the ground. I’ve never got a better look at one of these.