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Wildlife Report: Protecting Maine's Endangered Invertebrates

September 03, 2008 - AUGUSTA -- The wildlife division of the Maine Department of Inland Fisheries & Wildlife is responsible for the conservation of the full diversity of Maine’s wildlife.

Maine is home to 18 species of frogs, toads and salamanders (amphibians), 16 species of turtles and snakes (reptiles), and more than 15,000 species of terrestrial and freshwater invertebrates, from beetles and butterflies to mayflies and mussels, to name a few.

One of the division’s highest priorities is to address the protection and recovery needs of reptiles and invertebrates on the state’s official list of endangered and threatened species (21 of 45 species). Some state endangered invertebrates, such as the Katahdin Arctic butterfly, are endemics – found nowhere else in the world but Maine.

RARE DRAGONFLIES

Insects in the order Odonata, damselflies and dragonflies, are a significant and conspicuous component of Maine’s wildlife diversity. Scientiests have documented 158 species in the state, nearly 36 percent of the total North American fauna.

Several of Maine’s odonate species are of national and global conservation concern. In 1997, at the department’s request, the Legislature designated the ringed boghaunter dragonfly (Williamsonia lintneri) as endangered, and the pygmy snaketail dragonfly (Ophiogomphus howei) as threatened.

The department lists an additional 25 odonates as species of special concern. While several odonates are highly sensitive to freshwater habitat degradation and are experiencing declines nationwide, baseline information for the group has been lacking in Maine until recently.

In 1998, MDIFW received a grant from the Outdoor Heritage Fund to initiate the Maine Damselfly and Dragonfly Survey. In addition to engaging over 200 of Maine’s non-game wildlife constituents and raising public awareness of invertebrate conservation, the survey has helped the department more accurately assess the status of odonates. The survey’s results have far exceeded expectations.

With the volunteer atlasing component of the survey coming to closure, the department has contracted Paul M. Brunelle, an accomplished odonate expert and graphic design artist from Nova Scotia, to help write and design the project’s capstone product: “An Atlas and Conservation Assessment of Acadia’s Damselfly and Dragonfly Fauna.”

Populated largely with data contributed by survey volunteers, this atlas will serve as the first authoritative publication on the distribution and natural history of odonates from Maine and the Canadian Maritime Provinces.

RARE BUTTERFLIES

Hessel’s hairstreak, Clayton’s copper, purple lesser fritillary and crowberry blue are just some of the state’s rarest butterflies that are both colorful in name and on the wing. The department is studying the group during statewide regional surveys.

It received a grant from the Outdoor Heritage Fund in 2002 to contract a professional lepidopterist, Reginald Webster of New Brunswick, to help assemble a comprehensive assessment of the state’s butterfly fauna. Drawing from published literature and specimen records in museums and amateur collections throughout the Northeast, Webster assembled the first baseline atlas and database of Maine’s butterfly fauna.

The baseline atlas project compiled nearly 9,000 records and added 11 previously undocumented butterflies to the state list, which now stands at 115 species. Of special note is the relatively high proportion of Maine butterflies and skippers that are extirpated (five species) or state-listed as endangered, threatened, or special concern (18 species), a pattern consistent with global trends elsewhere. Unfortunately, additional endangered and threatened butterfly listings are imminent as a result of the state’s recent assessment efforts.

Contact MDIFW to receive an updated checklist of the butterflies of Maine (phillip.demaynadier@maine.gov) or visit www.state.me.us/ifw/wildlife/wildlife.htm to download a pdf copy of Maine’s first baseline butterfly atlas.

A statewide butterfly survey is ongoing. Sponsored by MDIFW, in partnership with the University of Maine at Farmington (Dr. Ron Butler), Colby College (Dr. Herb Wilson), and Dr. Reginald Webster of New Brunswick, the Maine Butterfly Survey is a five-year, statewide, volunteer survey effort.

Check the MBS web site for further details (http://mbs.umf.maine.edu) or contact the volunteer coordinator, Dr. Herb Wilson, at whwilson@colby.edu.

CLAYTON’S COPPER BUTTERFLY

The Clayton’s copper (Lycaena dorcas claytoni) is a small, orange-brown butterfly known only from a handful of sites in Maine and western New Brunswick.

In Maine, most of our occurrences are centered in a 10 square mile area around Lee and Springfield in northeastern Penobscot County. Three sites in northern Piscataquis County and two in Aroostook County have also been documented. Only one site, Dwinal Pond flowage in Lee and Winn, is known to support a large population (thousands) of Clayton’s copper.

This butterfly is believed to be an isolated subspecies of the more widely distributed Dorcas copper (Lycaena dorcas), which is found across much of northern and western North America.

Clayton’s copper is found only in association with its single larval host plant, the shrubby cinquefoil (Pentaphylloides floribunda). This uncommon shrub requires limestone soils and has a scattered distribution throughout Maine. Although not considered rare, it occurs in few stands large enough to support viable Clayton’s copper populations. In Maine, shrubby cinquefoil typically occurs along the edge of calcareous wetlands (i.e. rich in calcium carbonate or limestone), which are also uncommon in Maine.

Clayton’s copper butterflies take one year to complete their life cycle. In late July and August, when shrubby cinquefoil is blooming, females lay their eggs singly on the underside of cinquefoil leaves. Leaves and eggs drop to the ground in autumn, and the eggs overwinter. The pale green larvae hatch in spring and crawl back up the plant to feed on its leaves. After the larvae molt and pupate in early summer, adult butterflies emerge during July and August to start the cycle over again. Throughout the flight period, Clayton’s copper remains local to its cinquefoil stands, where the abundant yellow flowers provide its primary nectar source.

Clayton’s copper is listed as “endangered” in Maine because of the extremely limited number, size and distribution of its populations, the limited availability of its habitat, and its near-endemic status in Maine. Forest succession, impoundments, and dewatering of wetlands for irrigation are the most serious threats to this butterfly and its habitat.

In 2006, several grants were awarded to the department and the University of Maine to investigate two key questions about this rare butterfly. Emily Knurek, a graduate student at the university, is implementing a survey protocol to estimate the size of Maine’s Clayton’s copper populations. She will also investigate the butterfly’s taxonomic status. While most lepidopterists accept the subspecific status of Clayton’s copper, others doubt its validity – especially since the taxonomic distinction between Clayton’s and Dorcas Copper has never been quantified.

ROARING BROOK MAYFLY

In 1939, T.H. Frison climbed Mount Katahdin and unknowingly made a discovery that would one day puzzle the experts. Frison, a well-known Illinois entomologist, was collecting mayflies and stoneflies as he and his family hiked to Chimney Pond.

Several years later, one of those mayfly specimens would be described as a new species. Aptly named in memory of its collector, Epeorus frisoni went largely unnoticed for another half century. But in the early 1990s, biologists began updating Maine’s endangered species list and, for the first time, were considering the status of invertebrates. Mayflies were a well-studied group of insects, yet here was a species that had never been found anywhere else in the world. This long history of a single occurrence, despite extensive collections and surveys of mayflies throughout Maine and North America, ultimately led to Epeorus frisoni being listed as endangered in Maine in 1997.

Unofficially dubbed the “Roaring Brook mayfly,” this little insect remained a big mystery to biologists now responsible for ensuring its conservation. Nothing was known about its life history, habitat requirements, or conservation needs. Its current status and distribution on Katahdin were also unknown, since no one had looked for it there since its original collection.

To complicate matters, the species’ taxonomic validity had come under question. Its similarity to a closely related species had led at least one mayfly expert to suggest that the original specimen might be just a variant form of a more common Epeorus species found in Maine.

Recently, with special permission from Baxter State Park, the department surveyed Roaring Brook and two of its tributaries to collect specimens of the Epeorus species that occur there. With the expert help of Dr. Steven Burian, a mayfly taxonomist from Southern Connecticut State University, the department was able to confirm that some of the specimens collected from the two tributaries of Roaring Brook matched the specimen collected by Frison in 1939. By comparing them to other species of Epeorus found in Maine, we were also able to confirm that Epeorus frisoni was indeed a distinct and valid species.

Since then, Burian has also located a specimen of E. frisoni in a recent collection from Vermont. While it now appears the Roaring Brook mayfly is not endemic just to Katahdin or to Maine, its status as a “narrow endemic” (i.e., having an extremely limited distribution) is very rare, and E. frisoni is the only mayfly known to be endemic to New England. Its single occurrence in Maine also continues to support the species’ listing status as state-endangered. In 2005-2006, the department continued surveys for the Roaring Brook mayfly as part of ongoing ecoregional surveys for rare species. While high-elevation, headwater streams are not a common habitat type in the targeted Eastern Lowlands and Aroostook Hills and Lowlands ecoregions, streams on several of the highest peaks were sampled. No Epeorus frisoni were found. In 2007, the department began surveys in the western and Central Mountains ecoregions – two areas of the state that hold the greatest promise of finding new occurrences of this rare mayfly.

By PHILLIP de MAYNADIER and BETH SWARTZ, Portland Press Herald, August 28, 2008


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