INTERPRETATION OF DATA

There is no requirement that individual sites evaluate or interpret the data. Nonetheless, some sites have chosen to do so and some of this information is provided here. The long term goal is to make all of the data available statewide.

Here is a little background data based on what has already been learned about abundance monitoring in Ohio, from 1995-8. First, the beginning surveyor may be intimidated by the number of species of butterflies in Ohio, but one should understand that at any one site the diversity is much smaller. For example, here is a graph demonstrating the number of different species in a given week at two distinctly different transects. Koelliker Fen is a wetland habitat with little available nectar late in the season. Penitentiary Glen is primarily open meadow habitat with some woods. At the beginning of the season, there are fewer than ten species of butterflies flying. This provides an opportunity for the beginner to sort out a few species before things get more confusing during the middle of the season, when perhaps twenty to twenty-five species may be present if the habitat is suitable.

It is useful to identify which butterflies are most common and learn to recognize these first, because these will be most often counted. The table below lists the fifteen most commonly seen butterflies in Ohio, based on four years of transect data. The top five represent 35% of the butterflies counted, the top ten 50% and the top fifteen represent 68% of all butterflies counted.

The data above are based primarily on transects from the northern half of the state, so there may be differences in different habitats and in other geographic regions.

Overall seasonal abundance in Ohio follows the graph shown above, based on all data contributed from sites during 1995-98. There is peak in abundance around July 1st (week14), with a drop in abundance until later broods again populate the curve from weeks 18 on. This curve shifts to the left in warmer parts of the state, but data are unavailable at present to document this. (Please collect some!).

Another useful result of long term butterfly abundance monitoring is to get more information regarding the flight period of individual species. Most of this information is currently based on fresh museum specimens and anecdotal recall from experienced lepidopterists. Ideally, flight period information from different climate zones within Ohio would be useful.

The above graph illustrates the flight period for two common Ohio satyrs, based on 1996 data from eight sites. The common wood nymph has a protracted flight period whereas the little wood satyr appears and is gone in several weeks. Much is yet to be learned from this data, especially when weather and geographic factors are considered.

Finally, the abundance within a given transect also provides useful information which may help direct land management of an area. This is illustrated above. The number of butterflies counted in each of nine sections comprising the Koelliker Fen transect are presented. Section one is the edge of a woods and has transition zone butterflies present. Sections two and eight are woods, which are relatively devoid of butterflies. Section three is the fen, which supports primarily unique wetland butterflies. Sections six, seven, and nine represent open meadow habitats and are the most supportive of high butterfly densities at the present time. Over time, the relative abundance in each section will change as succession and land management changes occur.

There is much to be learned over time. It is hoped that many sites will continue monitoring for ten to twenty years so that long term effects can begin to be understood. Ohio is in a unique position to lead this effort through this study.