Butterfly Monitoring Report - 2003
by M.B. Plona

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History of Butterfly Collecting
Methodology | Transect Locations
Discussion | Regional Trends
Future Monitoring | References

History of Butterfly Collecting in Ohio
The study of Ohio butterflies and skippers (Lepidoptera) began as early as 1837. By 1897, Edward W. Claypole published a list of 48 species of butterflies for Summit County. John C. Pallister, an entomologist with the Cleveland Museum of Natural History, collected Lepidoptera in northeastern Ohio from 1924-1931. Since the 1960s, the understanding of butterfly fauna increased at a dramatic pace. In 1979 the Ohio Lepidopterists was founded to promote interest in and to provide information about butterflies, skippers, and moths of Ohio and neighboring states. In 1982, the first updated State list (since 1899) was provided. By 1986 the Ohio Lepidopterist Society and the Ohio Department of Natural Resources, Division of Wildlife, initiated the Ohio Survey of Lepidoptera. This survey documented the species of Lepidoptera present in Ohio, their distributions, and identified species endangered or threatened (Iftner, et.al, 1992).

Butterflies are important pollinators and are also significant in nutrient cycling, both as consumers and as prey for other species. Many species are restricted to unique ecological conditions, making them valuable indicators of ecosystem quality and change.

Of the approximately 700 American butterfly species, 144 have been reported in Ohio . Some have appeared in all 88 counties while others are very rare. Most of what is known about the butterflies of Ohio is based on museum specimens and anecdotal information from experienced lepidopterists.

Some species of butterflies and moths are in danger of disappearing from Ohio. Currently there are eight species of state-listed endangered butterflies, one threatened, one species of concern, one species of special interest and one extirpated species in Ohio. Two of the eight state-listed endangered butterflies, Karner blue and Mitchell's satyr are also on the federal endangered list designation (ODNR, 2004). None of these threatened and endangered species have been recorded as being present in the park. The Ohio butterflies most in danger of extirpation are those dependent on larval food plants that grow in wetlands, most of which have been drained or developed (Platt, 1998).

Proposed reasons for declines in butterfly abundance in Ohio include habitat changes and pesticide use. Long term data that track regional and local trends in abundance are essential in revealing population declines before their final stages. Declines are hard to detect when they occur slowly and/or lag years behind their causes (Rzeszotarski, 1999).

In 1996 Cuyahoga Valley National Park (CVNP) was invited to participate in a long term butterfly monitoring program initiated by the Cleveland Museum of Natural History. The program was expanded statewide in 1998 by the Ohio Lepidopterists and now includes over 60 sites. This report summarizes the 1996-2003 monitoring seasons in CVNP.

Methodology
The method used for monitoring butterflies was originally developed at Monks Wood Experimental Station in Great Britain, and details of the methodology have been published (Pollard, 1991; Pollard and Yates, 1993).

In 1996, two transects in CVNP were selected along a fixed route. Transects were circular routes, less than 1 ½ miles in length and marked with stakes. Transects were selected to travel through as many different habitats as possible. Transects were walked at least once a week at the height of the season (May through September). Transects were divided into ten sections. Each section signified a discrete habitat type or subdivision of the same habitat only managed differently. Once the sections were defined, they will not be changed from year to year. Notes, photographs and video describing the different habitat types in each section were recorded. The dominant plant species in each section and nectar sources were also recorded.

Transects were walked at an even pace and the butterflies which were within 15 feet of the observer were recorded. Observers imagined themselves in a box defined by 15 feet (7.5 feet to either side), counting only those butterflies which pass through the box as they walk the transect. Individuals that were seen previously and flew back into the survey were recorded only once. Butterflies were observed through binoculars, or examined more closely with the use of a net to be sure of identification. Butterflies that were not identified were photographed for later identification and then released. Occasionally voucher specimens were collected for identification by museum experts.

The monitoring season began on April 1 and ended on September 30. However, weather warmer than 65 F prior to April 1 and after September 30 extended the survey season. Monitoring occurred between 11 a.m. and 5 p.m. Temperatures and percent cloudiness was recorded. Transects were not walked if temperatures were less than 60 F. Between 60-65 F, transects were walked provided it was sunny for at least 75% of the sections. Between 65-70 F, transects were walked provided it was sunny for at least 50% of the sections. Above 70 F transects were walked in any conditions except rain. Wind speed and direction were estimated using the Beaufort wind scale. Butterfly transects were not walked when wind speed exceeded 19-24 mph.

Species were recorded per each section along with any larvae observed. Energy sources, both nectar and other sources such as sap, fruit and feces were also noted.

Transect Locations
In 1996 two transect locations in CVNP were selected for the long term butterfly monitoring program. These transects were established at Terra Vista on Tinkers Creek Road in the Village of Valley View (Cuyahoga County) and the Armington Pond area on Quick Road in Boston Township (Summit County). These sites were selected in order to place transects in the northern and southern ends of the park, and also to cover two counties. After two monitoring seasons the Armington transect was discontinued due to lack of personnel and the potential of future agricultural development of the transect area.

Terra Vista is diverse in butterflies and habitats. The site is a former sand and gravel removal operation that has been restored naturally. The area is scrub, old field in various stages of succession. The area is also transected by a mowed utility right-of way and intermittent wetland potholes dot the landscape. Willows and autumn olives are the dominant tree species. Old fields form some of the most important butterfly habitats in Ohio because they have been allowed through succession to develop into diverse assemblages of herbaceous plants. Other habitats such as utility line rights-of way are maintained in early successional states by periodic disturbance (mowing). These habitats often develop a very diverse herbaceous flora which supports some of Ohio 's rarest butterflies (Iftner, et.al 1992). Therefore, the transect at Terra Vista will remain a long term monitoring site. The data described in this report will be specific to Terra Vista.

Discussion
The Cleveland Museum of Natural History will complete analysis of regional data as a separate report. Long term data will provide information on changes in butterfly abundance, colonization and extinction as habitats change, expansion and reductions in ranges, migrations, and immigrations of non-native species, flight periods, seasonal variations and overall health of butterflies in Ohio (Rzeszotarski, 1999). The long term goal is to make all of the data available statewide via an internet web page (http://www.ohiolepidopterists.org/bflymonitoring).

In 2003, species highlights for Terra Vista included the highest counts for all reporting sites statewide for the American Copper, Eastern Tailed Blue, Acadian Hairstreak and Pearl Crescent . The Acadian Hairstreak was recorded at only three monitoring sites statewide. Indian hemp, Apocynum cannabinum, and dogbane, Apocynum spp. are favorite adult energy sources that are abundant at Terra Vista. The Acadian Hairstreak depends on wetland and willow habitat, also present at Terra Vista. Edward's Hairstreak, one of the least recorded butterflies for records in 2003 throughout the state, was also observed at Terra Vista. The Edward's Hairstreak is a resident species for Ohio , but considered rare. While the host plant for this butterfly is closely associated with oaks, adult energy sources are common milkweed, Asclepias syriaca and butterfly-weed, Asclepias tuberosa. Edward's hairstreak is also considered to be myrmecophilic (mutually supporting) with the ant species Formica integra and may be dependent on this ant for survival (Iftner et al). If the butterfly is dependent on ants, then soil type could directly influence the distribution of the hairstreak. Known habitats of Edward's hairstreak are xeric (dry) and open areas, characterized by herbaceous prairie plants. Consequently, this butterfly could be a useful indicator of unique habitats.

A total of 54 butterfly species have been recorded at Terra Vista since the survey began in 1996. The following table lists the total number of butterflies counted by species each year at Terra Vista.

The top ten species reported over the last 5 years (1999-2003) at Terra Vista are:

European Cabbage White
Pearl Crescent
Alfalfa (Orange Sulphur )
Great Spangled Fritillary
Common Wood Nymph
Eastern Tailed Blue
Clouded Sulphur
Silver-spotted Skipper
Zabulon Skipper
Viceroy

Regional Trends
Dave Horn, Department of Entomology, The Ohio State University, has analyzed some of the long term data for monitoring sites in northeastern Ohio (including Terra Vista) that have eight years of data. Horn states that there needs to be a difference of 25% of the previous years total to detect a biologically significant difference in a species. In general, trends show that there are increases in the number of species after the first three years of monitoring followed by some declines. This can be partially attributed to the learning curve of the observers and partly to real increases and decreases in butterfly species. Compared to vertebrates, insects have a much higher reproductive potential and therefore their populations will cycle. Butterflies are extremely resilient and respond to different environmental factors. They do not all decline and increase in the same years. The questions that the long term monitoring program is interested in answering are: Are these cycles regular or predictable? Do the monitoring data reflect what we do know, or can predict, about butterfly populations based on knowledge of their biology? Horn's analysis highlights some regional trends for northeast Ohio which include:

• Eastern Tiger Swallowtail: showing cycles of increases followed by decreases; too soon to tell if this is a trend with this butterfly or part of their cycle.
• Monarchs: showing cycles of significant increases and decreases. Monarch population fluctuations are showing same patterns as other butterflies. Most recent decrease in 2002 which was also the year of the big die-off in Mexico due to weather conditions and habitat alteration.
• Red-spotted purple: declines in this butterfly, with little rebound, warrant placing it on the "watch list."
• Red Admiral: large boom in 2001. This species has recorded "booms and busts" since the 1830s, and this is a typical cycle for this butterfly. It is well-known to be an "irruptive" species, occasionally occurs in huge numbers, perhaps due to favorable winters in Ohio and southward.
• Buckeye: seems to be more common after mild winters; this was the case for northeastern Ohio and Erie County but not for Summit County or Central Ohio.
• Fiery Skipper: another southern species that (like the Buckeye) does not tolerate freezing well. The mild winters of the late 1990s saw an incursion of fiery skippers in northeastern transects and numbers were generally down in 2001.
• Wild Indigo Dusky Wing: the skipper recently broadened its larval host-plant preference to include crown vetch, a widely planted crop. This host-plant expansion has resulted in a dramatic increase in populations of the skipper in all areas of Ohio and elsewhere.
• Spicebush Swallowtail: large increase in 1999, followed by decrease. Regular cycle or predictable?
• All hairstreaks: an increase in hairstreaks was noted in 2000-01 and then decreasing in 2002. This decrease in all hairstreaks may be a declining trend.
• Duskwings (Horace's, Juvenal, Dreamy): these duskywings showing some reduction in numbers.
• West Virginia White: this species is occasionally seen in our region. Its host plants are the toothworts which may be threatened by the spread of the invasive non-native species, garlic mustard.

Future Monitoring
The greatest threats to most butterfly populations are habitat destruction and environmental degradation. Extirpation of certain species of butterflies in Ohio probably resulted from the draining of wetlands for agricultural use. A newer threat to Ohio’s butterfly diversity is the gypsy moth (Lymantria dispar (L.)). This forest defoliator can reach extremely high larval densities, and is capable of defoliating large tracts of forest. However the human response to the pest may cause ecological damage (Iftner, et.al, 1992). Pesticides used to control gypsy moths can affect butterflies with limited distributions and early spring larvae. Biological pesticides (Bt and Gypchek) were used in and around the park to suppress the outbreak of gypsy moth in May 2000 and may be used in the future in the event of another outbreak. If Terra Vista is managed for gypsy moths in future years we may notice a decline in abundance and species diversity depending on the biological pesticide that is selected. Baseline data from Terra Vista may be useful to monitor any affects on non-targeted Lepidoptera species in treated areas in the future.

While differences in abundance are apparent from year to year, the diversity of species has not decreased. Many species fly for only 2-3 week periods each year and this may result in year to year differences in the timing of adult activity patterns. Butterfly activity is also dependent upon weather patterns. The arrival of warm weather has a major influence on the phase of adult flight periods. Park staff and volunteers will continue to monitor butterflies as part of a long-term statewide effort. Long-term data (ten to twenty years) is necessary in order to begin to understand trends.

References
Iftner, David C., John A. Shuey, and John v. Calhoun. 1992. Butterflies and Skippers of Ohio. Ohio Biological Survey Bulletin. NS 9(1). Columbus, Ohio. 212 p.

Ohio Department of Natural Resources, Division of Wildlife. Wildlife that are Considered to be Endangered, Threatened, Species of Concern, Special Interest, Extirpated, or Extinct in Ohio. May 2004.

Platt, Carolyn V. 1998. Creatures of Change. An Album of Ohio Animals, Kent State University Press, Ohio.

Rzeszotarski, Mark S. 1999. The Ohio Lepidopterists Long-Term Monitoring of Butterfies. Unpublished.

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