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The Butterflies of Massachusetts
This appealing little skipper has extended its range south into Massachusetts since the time of Samuel Scudder, but may be negatively affected in the future by climate warming. It is a boreal (not an arctic) habitat specialist, but surprisingly has been found fairly often in Massachusetts in recent years. It is holarctic, and is declining or threatened in Great Britain and Japan, though seemingly stable in North America (Asher et al. 2001; Cech 2005).
Samuel Scudder and W. H. Edwards called this the “Mandan” skipper (Pamphila mandan), after a Native American group along the Missouri River. Scudder wrote “It occurs also, in New England, being not uncommon in the higher valleys of the White Mountains, as along the Glen road and along the roads into the ravines and through the notches in the vicinity of Crawford’s and of Fabyan’s....” (1889:1572). Scudder’s only New England specimens and reports came from New Hampshire and Maine; most were from Canada, and he had no specimens or reports from Massachusetts. Harris (1862) does not list this species. Maynard (1886) had “never met with this skipper living,” and thought it was rare. There are no early Massachusetts records in the Harvard MCZ, or other museum collections. The first state record seems to be from the northern town of Phillipston in the early 1930's, taken by H. H. Shepard, who referred to it as “my best capture” (Farquhar 1934; specimen location unknown).
Photo: Moran WMA, Windsor, Mass., F. Model, June 2, 2006
Host Plants and Habitat
Arctic Skipper is not limited to boreal habitats, but ranges from sub-arctic tundra in the north to transitional forest areas to the south. It is found today in Massachusetts in small colonies “in well lit grassy areas near wooded habitats; typical locations include grass-lined forest paths and glades” (Walton, 1986-90 Atlas). Rangewide, its habitats are wet meadows, wetland edges, and moist valleys (Scott 1986; Layberry 1998; Cech 2005; O’Donnell et al. 2007). In Massachusetts it is often found nectaring on early-blooming wild geranium (Geranium maculatum), a common wildflower native to all counties here.
The specific host grasses in Massachusetts are still unknown, but Calamagrostis, Bromus and Panicum species are used elsewhere (Scott, 1986; Scudder 1889:1573). Calamagrostis canadensis, a wet meadow grass which is common throughout New England and found in every county in Massachusetts (Sorrie and Somers 1999), is a possible host here. Like several other skipper species, Arctic Skipper females will oviposit on Kentucky bluegrass (Poa pratensis) in the lab, and larvae will grow to maturity on it, as demonstrated recently during the Connecticut Atlas project (O’Donnell et al. 2007; Scudder 1889:1572). Use of this grass in the wild might account for the Arctic’s relatively robust presence in Massachusetts.
Relative Abundance Today
Scudder’s 19th century reports had set the southern limit of this species as northern New Hampshire and Maine. By the 1970’s evidence had begun accumulating that the skipper was increasing in Massachusetts (Table 2). In 1965 C. G. Oliver reported Arctic Skipper from the Acton area, adding that it was easy to find in late May. In 1971 Edward M. Peters reported a specimen from Sudbury, and in 1972 one from the vicinity of Carlisle, and he remarked that this was the first time this species had been seen in Carlisle. (Lep. Soc Seas Sum. Corresp.)
In 1973 there were three reports : D. Winter captured two in Dunstable near the New Hampshire border on June 9 (specimens in the Harvard MCZ), J. Ingraham found one in Dover on July 1, and T. Franks found one in Wellesley on June 6. Winter notes that “the latter two records seem unusual for this northern species,” but he reported them in the Lepidopterists’ Society Season Summary as a “good range extension” (Lep. Soc. Seas. Sum. and Correspondence, 1959-1976).
The 1995-99 Connecticut Atlas had only one 1940 record from all the pre-project years (1896-1994) in that state, but amassed six records during the project period. Amateur Connecticut butterfly observers in the project period also reported many other sightings of Arctic Skipper around Union and in Litchfield. The greater number of Connecticut Atlas project records compared to pre-project remained unexplained in the final write-up, but was attributed mainly to greater collecting effort rather than range expansion. However, looked at in a larger time frame and in regional context, it seems obvious that a southward range expansion since Scudder’s time has in fact taken place.
Both the Massachusetts 1986-90 Atlas and 2000-2007 MBC records rank Arctic Skipper on the lower end of “Uncommon” in the state (Table 5), placing it on a par with such species as Meadow Fritillary, Hoary Edge, and West Virginia White in terms of frequency of sightings. It is not Rare.
The trend in MBC sightings per trip reports has been strongly upward since 1992 (Chart 85), further documenting the increase in this skipper’s numbers here. But there are variations from year to year.
Chart 85: MBC Sightings per Total Trip Reports 1992-2009
In addition, in 2007, 2008, and 2009 the average number of Arctic Skippers per report of that species increased 100, 200, and 300% in comparison to the average for the preceding years back to 1994 (Nielsen, Season Summary, MB 2008, 2009, 2010).
State Distribution and Locations
Map 85: MBC Sightings by Town 1992-2009
Both MBC records (Map 85) and the 1986-90 MAS Atlas show Arctic Skipper distributed from western Massachusetts east to Essex County, and absent from the entire southeastern coastal plain, the Cape and the islands, and the lower Connecticut River valley. MBC has Arctic Skipper records for 33 of approximately 300 total recorded towns. (Cummington should appear on the map above.)
There are few MBC reports from southern Berkshire County, but the Atlas found it there. The Atlas did not find Arctic Skipper in the central region centered around Quabbin Reservoir---instead there seemed to be a gap between Berkshire County and the Worcester area. MBC records therefore add new sightings for many towns in the central part of the state, including Hubbardston/Rutland (Barre Falls SP), Orange (Tully Meadow), Paxton (Moore SP), Worcester (BMB), Upton, Petersham, Ashburnham, and Stow (Delaney SP).
The eastern-most sighting in MBC records is Topsfield (Ipswich River WS 5/28/1998, F. Goodwin); there are also MBC reports of singles from Groveland and North Andover, but none more recent than 2001. The presence of this skipper in Essex County needs re-confirmation.
The southeastern-most sighting is a single in Foxborough (Lamson Rd., 6/7/2007, M. Champagne). This also needs confirmation as to whether there is an ongoing colony. Towns with a good depth of records are Princeton, Sudbury, Concord, and Acton.
The species is still absent from the southeast coastal plain. Mello & Hansen (2004) do not list it for Cape Cod, and Pelikan does not list it in the Martha’s Vineyard checklist (2002).
The most well-known and productive location for Arctic Skipper has been Moran Wildlife Management Area in Windsor (Berkshire County). This location has been visited every year since 1999, and in fact most of the pattern shown in Chart 85 reflects counts made at this location. The maximum counted there was 130 on 6/6/2009 on an MBC trip led by T Gagnon. All other locations pale by comparison. The next highest counts are 10 at October Mountain SF in Lee/Washington (6/5/1999); 7 at Greylock Glen in Adams (6/6/2001, P. Weatherbee); 5 in Chelmsford (5/29/1998, B. Cassie), and 4 in Petersham 5/29/1999. All other reports are of even smaller numbers. The Atlas quotes a high of 11 on 6/10/1989 in Harvard.
Broods and Flight period
Arctic Skipper is univoltine, its single flight lasting from the third week of May through June in recent years, according to the MBC flight chart (http://www.naba.org/chapters/nabambc/flight-dates-chart.asp). The Atlas had reported a shorter flight period of “late May to mid-June”, but a few MBC flight dates are both earlier and later than that. In addition, the peak flight date seems earlier. The Atlas reported a “peak in the second week of June”, whereas MBC flight data show the most numbers flying in the first week of June.
The earliest MBC sighting dates 1992-2009 are 5/20/2009 Royalston, C. Kamp + A. Mayo, and 5/20/1998 Worcester, Broad Meadow Brook, J. Mullen et al. In 2012, Arctic Skipper was photographed in Ashburnham on 5/23 by G. Dysart. The Atlas early date had been 5/27/1986, Sudbury, D. Walton.
The latest MBC sighting dates are 7/11/1992 Central Franklin NABA Count, M. Fairbrother, 6/27/2004 Royalston, C. Kamp, and 6/26/2002 Hubbardston/Rutland Barre Falls Dam, M. Lynch and S. Carroll. The Atlas late date had been 6/26/1988, Otis, E. Dunbar.
Comparison with 19th century flight dates is not possible because the species was not recorded here then, but these recent ‘straws in the wind’ suggest that the flight period might be beginning or peaking earlier.
Outlook
The chief threat to Arctic Skipper in Massachusetts is probably climate change, as warming could result in a contraction northward of the range (Table 6). The species is listed as S3 or “vulnerable” in Massachusetts by NatureServe (2010), and it is near the southern limit of its range here. Further research is needed on the precise host plant use and habitat in Massachusetts. In addition, Arctic Skipper is univoltine, limiting its numbers.
Northern Connecticut and Foxborough, Massachusetts are currently the southernmost known locations. It is not found on the Massachusetts coastal plain or in Rhode Island (Pavulaan and Gregg 2007). It was discovered in New Jersey in the late 1980’s, and was found at one location there for many years, but since 2006 it has not been seen there.
© Sharon Stichter 2010, 2011
page updated 9-9-2012
ABOUT BOM SPECIES LIST BUTTERFLY HISTORY PIONEER LEPIDOPTERISTS METHODS