One Hundred Butterflies in Massachusetts

For the 2023 season, I decided to do a Massachusetts butterfly big year. That is an effort to see as many species as possible. I had been intrigued by the idea ever since reading about birders doing big years, often for all of North America. That takes an incredible amount of time and money, but I thought a state-only butterfly big year would be approachable.

I often travel a lot, and my travel schedule would get in the way of doing a big year, since many species only fly for a short period. When the pandemic forced me to stay home, I tried to do a state butterfly big year in 2021. But I abandoned that effort about half-way through the year, because I felt guilty about the amount of gasoline I was burning driving across the state. By 2023 I had replaced my gasoline car with an all electric one. My travel has resumed somewhat, but I had no trips longer than four days planned between April and October of this year.

From talking to avid butterfliers who have been watching them in Massachusetts for many years, I know that as recently as ten years ago, it did not take heroic efforts to break 100 species in a year. I only started seriously looking for butterflies here about ten years ago, and in that time several species which were formerly easy to see had become difficult, with a few not seen in several years now. For instance, Hessel’s Hairstreak has not been confirmed since 2015, nor Common Roadside Skipper. Some species have become rare in just the last few years, with Harris’s Checkerspot and Acadian Hairstreak now only known from a few places.

I mostly used the Massachusetts Butterfly Club “Checklist of the Butterflies of Massachusetts” (2015) as my reference list. That list has 111 species on it, or 112 when you count the two subspecies of Limenitis arthemis as separate entries for White Admiral and Red-spotted Purple. I added a few species to this, rare southern strays that have only been recorded a few times but are listed in other MBC publications. I also added Northern Azure (see below). That put 120 species on my list. Surely I could manage to miss only 20 of these, right?

There are several taxonomic puzzles amongst our butterflies. These are still being debated, and this is not a discussion of those, rather how I approached them this year. For tiger swallowtails, I assumed they were all Eastern Tiger Swallowtails (Papilio glaucus) except for those at high altitude or in western Mass. before mid-July, where I checked field marks for Canadian Tiger Swallowtail (P. canadensis). I assumed all crescents were Pearl Crescent (Phyciodes tharos) and never checked to see if any were Northern Crescents (P. cocyta). Azures are more complicated. Some club members refer to “form lucia” of Spring Azure, and “A Catalogue of the Butterflies of the United States and Canada” by Jonathan Pelham recognizes Celastrina lucia as “Northern Azure” so I adopted that. Early in the season, those with dusky gray in the center of the wing and gray margins are Northern Azure (C. lucia), those with more crisp markings are Spring Azure (C. ladon). By late May and June, azures with fine black markings are probably Cherry Gall Azure (C. serotina). More heavily marked ones in June and all after that are Summer Azure (C. neglecta). This is an over simplification, but worked for quick field identification. For small dark skippers, the black witches, I attempted to properly identify them, and erred towards calling ambiguous ones Dun Skipper.

I kept myself organized with spreadsheets. One listed every target species (or subspecies), whether I had seen it, and whether I had gotten a photograph. I also noted the start and end of the flight period in the state so that I could sort the spreadsheet to see what is currently flying that I had not seen. I also kept a spreadsheet recording how many of each species I saw on every hike I did. I have been keeping data like this every year for a while now, so I could easily look up when and where I saw various species in past years. I record the time spent in the field and how far I walked as well, to make the data more valuable for scientific analysis in the future.

My Google Maps account has favorites saved of many of the places I go to look for butterflies. This is really helpful in planning each day’s outing. If I am preparing to go across the state to search for a particular butterfly, I can at a glance see what other places are nearby or on my way that might be worth stopping at as well. And because some of these places do not have names or proper street addresses, I also have a list of butterfly sites and the nearest street address, so that I can enter that into my car navigation system to get me there.

I tried to get a photo of every species. My usual method is to photograph at least one of every species I see on every outing. Yes, that means I have many photos of Cabbage Whites and other common species. That keeps me in practice getting photos, and means that I do not forget to photograph common species. I post most of these here on iNaturalist where I am very active both posting and identifying observations for others. I have a butterfly counting app on my phone similar to eBird which I wrote myself. It works pretty well, and one of these days I will polish a few rough edges and make it available for others.

My basic plan for the year was to plan trips for the butterflies with short flight periods or specialized habitats, and hope that while doing that I would pick up all of the widespread species. One problem I ran into was that most of the butterflies flying before mid-summer had their flight period running about a week later than usual. On my first trip down to Myles Standish State Forest in Plymouth for elfins almost nothing was flying, but a week later I saw what I was expecting. That happened on several trips, as I was reluctant to just assume they were flying late and risk missing something.

My year started in April, where I found Mourning Cloaks and Cabbage Whites, but failed to turn up an Eastern Comma until July. My first trip to see more than two species of butterfly was April 25, at Burma Road in Milton where I added Henry’s Elfin and two different azures to my list. On May 7, at Myles Standish SF I added three species of elfins and two duskywings. The next day I made my first trip out to western Mass., where I added Mustard White at Darey Housatonic Valley Wildlife Management Area in Lenox, but nothing else new. I ticked off species one at a time as I sought out the elfins and duskywings that fly early in the season. There is a spot in north central Mass. where Bog Elfin is usually reliable, yet I made three different trips there before I saw it, and it was only a brief view and I failed to get a photo.

The first Massachusetts Butterfly Club walk I joined was to Dinosaur Footprints and Mount Tom in Holyoke on May 19, where I saw Juniper Hairstreak and a couple of skippers, as well as visiting with friends I had not seen since the previous year.

By May 22 I had already made four trips to Horn Pond Mountain in Woburn, a favorite site with a lot of diversity that is not far from home. I was turning up very little there, which was worrisome. The electric company had done a lot of work on the power lines there the last two years, and chewed up a lot of the habitat. I thought it would bounce back, but several species that used to be reliable there I have not seen since 2020.

Late May is Hessel’s Hairstreak season. This is a species I have never seen, though I have spent the past few years searching, on my own and as part of the MBC effort organized by Danielle Desmarais. I went to Ponkapoag Bog in Canton, formerly a good place to see Hessel’s, and discovered that the boardwalk is now in such bad shape that even in knee-high boots I could not make it out to the best habitat. I should point out that technically I have seen Hessel’s: two years previously, at Ponkapoag, I was hanging out at the end of the boardwalk with another experienced butterflier, when a lycaenid passed about ten feet over our heads without stopping. I sure couldn’t defend an identification of that one, but given the date and location, Hessel’s was the only thing likely to have been flying. I also visited a couple of other Atlantic White Cedar sites as well this summer, including an invitation outing to a restricted property in Foxboro that was known to host the butterfly 20 years ago, but without luck now. As we reached mid-June, Hessel’s was the first species on my list I marked as “not seen” this year.

I drove west again in late May for Cobweb Skipper in Montague, and while in the area checked a couple of wetlands for some specialist skippers that mostly fly later, and they were not around yet. And then a couple of days later went west again for the annual butterfly club trip up Mount Greylock to see Early Hairstreaks. That club outing was successful, and I also picked up Canadian Tiger Swallowtail and West Virginia White (completing the resident whites), but not Pepper & Salt Skipper which is usually seen on that walk. In a surprise we saw two Compton Tortoiseshells that day, both very worn, and I was glad to get that species that I was not counting on. Nothing was flying at Eugene Moran Wildlife Management Area in Windsor that day so I failed to see Arctic Skipper.

By now I should have seen both Northern and Southern Cloudywings and Indian Skipper, all of which were formerly common on Horn Pond Mountain. A third trip down to Myles Standish got me Indian Skipper and completed the early season duskywings (Juvenal’s, Sleepy, Dreamy, and Wild Indigo). I had not expected to see Persius Duskywing, even though its last confirmed sighting was at Myles Standish. Persius joined Hessel’s on my “not seen” list by mid-June. Broad Meadow Brook in Worcester in the past has also been good for the Cloudywings, but I failed to turn them up there while picking up Hoary Edge.

The first two weeks in June I visited seven different sites in central Mass. looking for Harris’s Checkerspot. I did not find it in its former stronghold of Mass Audubon’s Broad Meadow Brook nor under various power lines in Shrewsbury, Worcester, or Grafton. Someone I didn’t know posted a photo of one to iNaturalist from an obscured location in Fitchburg. I messaged him to ask if he was willing to divulge the location. When he responded the next day, he was helpful, describing where he went to a difficult-to-access powerline cut and mentioning he had just run into a mutual friend from the butterfly club. I bushwacked there the next day, and did not find anything promising. I continued to check out historic sites for Harris’s and likely spots nearby found by studying satellite maps. The same iNat user messaged me a week later when he found another Harris’s at a different spot in Leominster. I shared this information with Garry Kessler, and the next morning we both went there and with Garry’s help I finally managed to see one, the first I had encountered in four years. During this time I also went back to Eugene Moran WMA again and picked up Arctic Skipper and Pepper & Salt Skipper.

On June 21 I made my first trip of the season to October Mountain State Forest in Washington, where I added Atlantis Fritillary, White Admiral, and some skippers. I would keep going back because it is a good place to see some of the rarer wetland skippers and satyrs. And I kept hitting spots in metro Boston that should have had Northern and Southern Cloudywing, but could not find them. I stopped by the lower Mystic Lake in Medford and easily found a Harvester to check that box. A visit to Burma Rd in Milton turned up plenty of Appalachian Browns as it usually does at this time of year.

The first week in July is usually a time with a lot of butterflies and Fourth of July butterfly counts. During this period I used to see bushes with dozens of hairstreaks of four or five species. I only had one trip this year that had more than two species or into double-digits in the count of individuals. I slowly added Edwards’s, Striped, Banded, and Coral Hairstreaks. I got invited to a special trip to restricted areas in Joint Base Cape Cod where we saw dozens of individuals of six species of hairstreak, including Acadian (the target of that trip). I was hoping for Oak Hairstreak which is often seen there, but we did not find any on this trip. Another participant on this trip saw a Northern Cloudywing, which I only saw flying away—my least satisfying sighting of the year. I missed participating in the Concord butterfly count as I usually do because it was the same day as the JBBC trip. I also missed the Essex County butterfly count because of a non-naturalist commitment, so I did not participate in any Fourth of July counts this year. In this period I also saw Bog Copper at Tully Dam in Royalston and Dion Skipper at another site in the area.

I made two trips to October Mountain SF in early July. The first turned out to be cloudy and cool (it wasn’t when I left home, but after the two and a half hour drive, I discovered I should have stayed home), and not much was flying. A few days later I tried again, and saw my only lifer of the season: Two-spotted Skipper. This rare butterfly is a wetlands specialist I had been looking for over several years. I was told where to look for it by a butterfly club member, but had been unlucky actually finding it over many attempts the last few years. This time I not only saw one, I saw three. That trip had all three greater fritillaries (Great Spangled, Aphrodite, and Atlantis), two fresh cooperative Compton Tortoiseshells, Northern Pearly-eye, and many other butterflies. This is why I like the site, even though it is so far from home.

I made my first trip of the year to Bartholomew’s Cobble in Sheffield during this time too. And there picked up a new state butterfly for me, Hackberry Emperor, and saw a few Hickory Hairstreaks. During that trip I saw my first Common Sootywing of the year and did not think much of it, but that turned out to be the only one I saw this year. I was hoping for American Snout, Gray Comma, and Meadow Fritillary there too, but those proved elusive on all three of my trips to Bart’s Cobble this year. My second Bart’s trip was a butterfly club walk, and after not finding any rarities, I stopped by Forest Park in Springfield on my way home, hoping I might find Tawny Emperor there. While I did not see the emperor, I did find a White-M Hairstreak—my second of the year, but the first was not cooperative for a photo.

I was now halfway through the season, and about 80% of the way through my butterfly list! I was feeling pretty good about this, though the remaining species were mostly ones that are difficult to find. It was not until July 17 at the Barber Reservation in Sherborn that I saw any Silver-bordered Fritillaries, having visited several other likely spots without luck. And none of those spots turned up Bronze Copper as they sometimes do. Crane Swamp Trail in Marlboro provided Broad-winged Skippers after striking out on those at a few places closer to home. Eyed Brown was at both Appleton Farm in Ipswich and on the Crane Swamp Trail. While I failed to turn up any Bronze Coppers in July, I was not worried because their September flight is usually more reliable. I made two trips out to Mountain Meadow Preserve in Williamstown hoping for Meadow Fritillary without luck. As long as I was in the area, I drove to the summit of Mount Greylock each of these days, to check for Milbert’s Tortoiseshell.

In August I started focusing on what I had missed in the expected species, as well as visiting sites along the coast that are the most likely for southern strays. I had to admit that I had missed Southern Cloudywing, the only supposed common species I missed this year, and had only the non-verifiable flyaway Northern Cloudywing. Yes, I wrote off Common Roadside Skipper and Oak Hairstreak, but the skipper has not been seen in several years and the hairstreak is not reported every year. I saw Horace’s Duskywing at Francis Crane WMA in Falmouth, completing the expected duskywings.

The southern skippers started arriving early. Zabulons were common by mid-August, and by the first of September Sachems were the most numerous skipper at most sites I visited. A butterfly club member tipped me off to a Fiery Skipper seen at Verrill Farm in Concord; I decided to chase it even though the species is often common in the fall. This was a good move, as that was the only one I saw this year. There were scattered reports of Ocola Skipper, but I was not seeing them at the usual sites (including Sylvan Nursery in Westport where I see them most years) or a day later at places others had reported them. I finally saw Ocola in mid-September at the Boston Nature Center in Mattapan.

There are also a few resident species that do not start flying until late summer. My first trip to Naskatucket Bay State Reservation in Mattapoisett was too early to get Red-banded Hairstreak; I had to go back a week later for them. I visited several likely spots for Giant Swallowtail without luck. I only saw that one on my last trip out to Bart’s Cobble. I made several trips to the Arnold Arboretum in Jamaica Plain looking for Pipevine Swallowtails, sometimes seen there because of extensive pipevines around their administration building. I did not see that species until a friend in Wareham told me he had one visiting his yard and it stuck around for the time it took me to drive there. That completed the swallowtails.

In September I saw Bronze Copper during their second brood, right on the dike trail of Great Meadows NWR in Concord. I found only a single Leonard’s Skipper at Francis Crane WMA in Falmouth, and good thing I found it there. The other place I usually see them, Mass Audubon’s Wellfleet Bay Wildlife Sanctuary, did not have any when I was on the outer Cape a week later. While in Provincetown for a non-naturalist event that weekend I saw two Cloudless Sulphurs fly by without stopping, and I also had passes like this down in Westport, but never got a photo. I found my first Common Buckeye of the year at Allen’s Pond Wildlife Refuge in Westport. Hopefully it is just an off year for this beautiful southern butterfly, rather than the end of their presence in the state.

I continued going into the field in late September and early October, finding a second Common Buckeye and several Ocola Skippers, but no new species. Long-tailed Skipper was the mostly likely addition at this point, and I heard reports of two of them from earlier in the season, but just could not find one myself. At this time of year, the most common butterflies at most sites are Cabbage White and the sulphurs, which presents the challenge of looking critically at each to make sure I am not overlooking a stray Checkered White or Little Yellow. Alas, I did not find any of those, nor did I hear of anyone else sighting one this year.

I ended the year having exactly hit my goal of one hundred species. But that includes two that I am not happy about. That fly-away Northern Cloudywing that I did not see well enough to identify, though it was clearly seen by an expert I trust. Also that Bog Elfin back in June, seen in the right place at the right time, but my sighting was less than ideal with no photo. I can’t be 100% sure it was not an Eastern Pine Elfin. The other species I failed to photograph was Cloudless Sulphur. But that one I am very confident I saw, and those familiar with the species know that it seldom stops for photos.

By The Numbers

I spent a lot more time on this than I thought I would. I spent 83 days in the field, logging 128 hikes to accumulate 9,036 minutes (over 6 days) hiking 171 miles. From my home in metro Boston, I drove west past Worcester 17 times. I was in the field most weekdays when the weather was good, when possible scheduling other things I needed to do only a few days out when the forecast was for rain. I literally hit all four corners of the state with Williamstown, Sheffield, West Newbury, and Westport. Here is a breakdown of the places I visited by property owner:

39 State
33 Municipal
19 Mass Audubon
9 Trustees of Reservations
7 Federal
7 Commercial
4 Other non-profit
3 Private
7 [not classified, mostly power line corridors of unclear ownership]

The site where I recorded the most species per mile walked was Lime Kiln Farm in Sheffield, with 15/mi. The site with the most individuals observed per mile walked as Mountain Meadow Preserve in Williamstown with 134/mi. The most new butterflies I got for my list on one hike was five, at Montague Sand Plain in Montague. I recorded 4,250 individual butterflies on my hikes this year.

I got one lifer this year: Two-spotted Skipper. I also saw a new state butterfly: Hackberry Emperor. There were only a few butterflies that I only saw a single individual of: Giant & Pipevine Swallowtails, Acadian Hairstreak, Frosted Elfin, Hackberry Emperor, Northern Cloudywing, Common Sootywing, Fiery Skipper, and Leonard’s Skipper. Among the species I did not see were two that I had expected to get: Variegated Fritillary and Southern Cloudywing. Among the others I missed were a few that were reported this year by other observers: Oak Hairstreak, Meadow Fritillary, Long-tailed Skipper, and Variegated Fritillary.

Given how much effort was involved, I probably will not try this again. I am curious if this was an off year, or if more species becoming hard to find is a trend. I fear that populations are continuing to dwindle, and it will become more and more difficult for someone to see one hundred butterfly species in Massachusetts. It will take time to determine that. I like having a challenge, but will pick something easier next time, like visiting every Mass Audubon and Trustees of Reservations property in the state.

Thanks to the members of the Massachusetts Butterfly Club and others who posted their sightings to the MassLep email list and the Massachusetts Butterflies Facebook page. These alerted when and where to look for some of the uncommon butterflies. Also the users of iNaturalist who posted butterflies, as I regularly searched there for species I was looking for. And special thanks to the handful of people who directly sent me information about butterflies they knew I was looking for, and even inviting me to their yards. The communications part of this effort was far easier today than it was 25 years ago before the Internet was in common use. Thanks also to the two commercial establishments that welcomed me to walk around their property. And finally to Brian Cassie for feedback on this article.

Publicado el 13 de octubre de 2023 a las 09:49 PM por maractwin maractwin

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That was a lot of time and effort but congratulations on achieving your goal! You got beautiful photographs!

Anotado por petdoc hace 8 meses

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