Ecological restoration treatments can significantly reduce the risk of unnaturally severe wildfire and increase the health of old-growth trees in southwestern ponderosa pine forests. Carefully planned thinning and prescribed burning treatments, sometimes followed by reseeding of native plant species or control of noxious species, can also promote the growth of understory plants. As a result, restoration work can have a great impact on the populations of animal species that rely on forest habitats

Minard, A.E.

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6Ecological Restoration InstituteNorthern Arizona UniversityP.O. Box 15017Flagstaff, AZ 86011-5017www.eri.nau.eduWorking Papers in Southwestern Ponderosa Pine Forest RestorationButterflies as Indicators of Restoration ProgressNovember 2003 Working Papers in Southwestern Ponderosa Pine Forest RestorationThe Ecological Restoration Institute at Northern Arizona University is a pioneer in researching,implementing, and monitoring ecological restoration of southwestern ponderosa pine forests.These forests have been significantly altered through more than a century of fire suppression, live-stock grazing, logging, and other ecosystem changes. As a result, ecological and recreational valuesof these forests have decreased, while the threat of large-scale fires has increased dramatically. TheERI is helping to restore these forests in collaboration with numerous public agencies. By allowingnatural processes such as fire to resume self-sustaining patterns, we hope to reestablish healthyforests that provide ecosystem services, wildlife habitat, and recreational opportunities.Every restoration project needs to be site-specific, but the detailed experience of field practitionersmay help guide practitioners elsewhere. The Working Papers series presents findings and manage-ment recommendations from research and observations by the ERI and its partner organizations.This publication would not have been possible without significant staff contributions and fundingfrom the Bureau of Land Management. The views and conclusions contained in this document arethose of the authors and should not be interpreted as representing the opinions or policies of theU.S. Government. Mention of trade names or commercial products does not constitute theirendorsement by the U.S. Government.1: Restoring the Uinkaret Mountains: Operational Lessons and Adaptive Management Practices2: Understory Plant Community Restoration in the Uinkaret Mountains, Arizona3: Protecting Old Trees from Prescribed Fire4: Fuels Treatments and Forest Restoration: An Analysis of Benefits5: Limiting Damage to Forest Soils During Restoration Butterflies as Indicators of Restoration Progress aIntroductionEcological restoration treatments can significantly reduce the risk of unnaturally severewildfire and increase the health of old-growth trees in southwestern ponderosa pineforests. Carefully planned thinning and prescribed burning treatments, sometimes fol-lowed by reseeding of native plant species or control of noxious species, can also pro-mote the growth of understory plants. As a result, restoration work can have a greatimpact on the populations of animal species that rely on forest habitats.This publication examines the effects of restoration treatments on butterflies. It alsoexplains how monitoring butterflies—which either professionals or volunteers can do—can serve as a useful indicator of restoration progress.Why Butterflies?Many animals are affected by restoration treatments, but butterflies are particularly use-ful indicators of ecological changes for several reasons.They are easy to watch. Although butterflies aren’t as important to pollination in ecosys-tems as bees, wasps, or flies, they are easier to monitor (Taron 1996). Butterflies tend tobe visible, and most are easily identified in the field.They are sensitive to habitat changes brought on by restoration. Restoration of pon-derosa pine forests can create localized habitat changes—including altered light intensityand air temperatures—that directly affect insects. Butterflies are sensitive to changes inthese microclimatic conditions. Warmer temperatures and stronger light allow males ofsome species to fly longer in search of mates, and may also allow adult butterflies to for-age longer (Meyer and Sisk 2001; Waltz 2001). In addition, increased understory growthcan result in more flowering and nectar production, thereby increasing food supplies foradult butterflies and other pollinators (Short and Negrón 2003).They can indicate what’s happening with plants and other animals. Changes in butter-fly populations can indicate important, yet less easily detected changes in populations ofother organisms. Butterfly larvae—caterpillars—live exclusively on particular species ofgrasses, forbs, shrubs, or trees. Therefore, the presence of certain species of butterflies andmoths indicates the presence of specific larval host plants in the area. Adult butterflies,on the other hand, generally utilize a variety of nectar-producing plants. For that reason,the number of adult butterflies can reflect the abundance and diversity of nectar-produc-ing plants.1Butterflies as Indicators of Restoration ProgressaHow Restoration Treatments Affect Butterfly HabitatButterflies react both to short-term and long-term habitat changes caused by restorationtreatments. Short-term changes generally include increased light levels and temperaturesdue to lower tree densities; longer-term changes may include higher diversity and abun-dance in understory vegetation brought about by thinning and prescribed burning.Understory vegetation may continue to change with time as succession and futureground fires continue to shape habitat conditions.Changes in microclimatic conditions and understory vegetation were quickly apparent inthe wake of ponderosa pine forest restoration treatments conducted in the 1990s in theFort Valley area, near Flagstaff, and near Mount Trumbull in far northern Arizona. Bothareas were intensively thinned in an effort to return forest stands to a structure resem-bling that present prior to European-American settlement (Covington et al. 1997). Thesetreatments removed most young trees. All trees old enough to have been standing priorto settlement were retained, along with enough younger trees to compensate for preset-tlement trees lost to earlier logging or to other mortality. The area near Mount Trumbullalso experienced a prescribed burn before butterfly monitoring began.These treatments dramatically increased sunlight and water available on the forest floor,and understory plant growth responded favorably. Near Mount Trumbull, treated areashad 26 times as many flowers available to nectar-feeders as untreated areas (Waltz andCovington 1999). As a result, Amy Waltz and W. Wallace Covington reported “at leasttwice as many [butterfly] species and up to eight times as many individuals” in sites twoyears after thinning and burning as in untreated sites. In a study conducted in FortValley, Cecilia Meyer and Thomas Sisk (2001) found that two butterfly species—orangesulphurs (Colia eurytheme) and pine whites (Neophasia menapia)—flew on sites earlierin the day at east-facing edges between forest that had been thinned several months earli-er than they did in unthinned stands, indicating that increased light intensity resultingfrom restoration prescriptions influences butterfly behavior. This was especially notice-able on sunny days, when increased light penetrated openings in the treatment areas.2Figure 1. Sample transectroutes through treated(speckled) and untreated(white) forest, with routesset at least 50 meters (164feet) from habitat edges. Butterflies as Indicators of Restoration Progress a3How to MonitorAnyone willing to spend a bit of time to learn survey and identification details can sur-vey butterflies and increase our understanding of restoration’s effects on animals.Butterflies are particularly well suited for monitoring by volunteers. Such groups asAudubon societies, garden clubs, Boy and Girl Scout troops, high school or universityscience students, and other youth and community groups may all be able to contributetime to volunteer monitoring projects. These simple steps can convert a small number ofsurvey hours into meaningful data:Establish transects. Butterflies are best surveyed along transects, or lines that passthrough particular habitat types (Pollard 1977). There is no set length, but 100 meters(328 feet) is a good starting point. They do not have to be straight lines, but be sure toestablish transects at least 50 meters (164 feet) away from habitat edges in order toensure that the butterflies observed along it are utilizing vegetation typical of the surveyarea (Figure 1). Set up transects in treated and untreated areas so that comparisons canbe made; mark them with colored flagging or other signs so that they can easily be relo-cated.Walk the transects. Ideally, visit your transects between four and six times during latespring and summer months, when insects are most active. Butterflies limit their move-ments on cool, cloudy days, so sunny days are best for observations. Avoid windy days.The hours from 10 a.m. to 4 p.m., when temperatures and butterfly activity are at theirhighest, are best. Transects should be walked at a casual but consistent pace, about fiveminutes for every 100 meters (328 feet). Scan the area near the transect, and recordwhatever is flying within five to ten meters (16 to 33 feet). Don’t be distracted by otherthings going on in the woods—such as birds or other animals—and survey transectsalone each so that the effort that goes into each survey is the same.Identify and count. With a pair of binoculars and a couple of guidebooks (listed below),identification doesn’t have to be difficult. Many butterflies are distinct and can be identi-fied in flight. For more difficult species, use a net for catch-and-release identification.Photographs can also be helpful, particularly sets of photos that feature both the topsand undersides of the wings. Species that are more difficult to identify from visible fea-tures, such as skippers, can be lumped together in surveys—for example, “brown skip-pers.” Do not kill or collect butterflies. Collecting can impact populations. In addition,several threatened and endangered butterfly species live in southwestern forests, andharming them is illegal.Compile the data. It is helpful to have one person or organization in charge of collectingand interpreting survey data. This might be a land management agency, university, ornonprofit organization, or it could be a single person. For more details about butterflymonitoring, see Pollard (1977) or the Web sites listed below. Butterflies as Indicators of Restoration Progressa4What to MonitorMuch remains to be learned about butterflies and how they respond to changing forestconditions. Butterfly monitors, whether professional or amateur, could make significantcontributions to science and to forest restoration by pursuing the following directions.Continued monitoring of restoration sites. Restored areas continue to evolve as under-story plant composition and microclimatic conditions continue to change. In addition,year-to-year variability can be very high in the Southwest (for example, wet and dry yearsmay support very different butterfly populations). For these reasons, butterfly monitor-ing should take into account not just short-term but also longer-term effects that showup over the years. As a starting point, consider monitoring one year following treatmentand then two to three years later.Establishing a baseline. Researchers don’t have a clear picture of what butterfly commu-nities once looked like in ponderosa pine forests. Surveys in forests that have continuedto experience relatively natural fire regimes, such as in the Gila Wilderness or on parts ofthe North Rim of the Grand Canyon, could help establish a baseline for comparison withforest areas from which fires have been excluded for many years.Monitor reproduction. Follow and watch adult butterflies for ovipositing (egg-laying)behavior. When laying eggs, a female butterfly curls her abdomen under and depositsone or several eggs on host plant stems or leaves, soil litter, tree trunks, or other surfaces.By flagging the site and returning in the following days and weeks, an observer can mon-itor hatching success, which is a direct indication of the abundance of the specific hostplants on which butterflies feed. For More InformationA number of different thinning prescriptions have been proposed for southwestern pon-derosa pine forests. Read about some on the ERI website at www.eri.nau.edu, or call us at928-523-7182.Written by Anne MinardReviewed by Peter Z. Fulé, Michele A. James, Patty Kohany, Kimberly Harding, Cecilia Meyer,Karen Short, Doug Taron, Diane Vosick, and Amy E. M. Waltz.Series Editor Peter Friederici  Northern Arizona University is an Equal Opportunity/Affirmative Action Institution   NAU Creative Communications/A52774/1M/11-03Field GuidesButterflies Through Binoculars, The West: A FieldGuide to the Butterflies of Western NorthAmerica by Jeffrey Glassberg (Oxford UniversityPress, 2001).National Audubon Society Field Guide to NorthAmerican Butterflies by Robert Michael Pyle(Knopf, 1981).The Butterflies of North America: A NaturalHistory and Field Guide by James A. Scott(Stanford University Press, 1992).A Field Guide to Western Butterflies by Paul A.Opler and Amy Bartlett Wright (Houghton Mifflin,1999).Butterflies of Arizona: A Photographic Guide byBob Stewart, Hank Brodkin, and Priscilla Brodkin(West Coast Lady Press, 2001).Web SitesFor free downloadable software that can help ana-lyze counts of butterflies or other insects, visitwww.urbanwildlands.org/INCA/.For a good example of a volunteer monitoring pro-tocol aimed at restoration sites, see Butterfly moni-toring guidelines for the Chicago region at www.mchenry.cc.il.us/faculty_pgs/mgarriso/but-terflyproject/aBMG.html#TableofContents.The North American Butterfly Association(www.naba.org) serves as a resource for butterflyfans, and each year seeks volunteers for its NABAButterfly Counts, usually held within a few weeksof July 4. The only NABA chapter in the Southwestis in southern Arizona;www.naba.org/chapters/nabasa/home.html.ReferencesCovington, W. W., P. Z. Fulé, M. M. Moore, S. C.Hart, T. E. Kolb, J. N. Mast, S. S. Sackett, and M. R.Wagner. 1997. Restoring ecosystem health in pon-derosa pine forests of the Southwest. Journal ofForestry 95(4):23–29.Meyer, C. L., and T. D. Sisk. 2001. Butterflyresponse to microclimatic conditions followingponderosa pine restoration. Restoration Ecology9:453–461.Pollard, E. 1977. A method for assessing changes inthe abundance of butterflies. BiologicalConservation 12:115–134.Short, K. C., and J. F. Negrón. 2003. Arthropodresponses: A functional approach. Pp. 286–305 inEcological restoration of southwestern ponderosa pineforests, ed. P. Friederici. Washington, D.C.: IslandPress.Taron, D. J. 1996. Insects. Pp. 305–318 in The tall-grass restoration handbook, ed. S. Packard and C.Mutel. Washington, D.C.: Island Press.Waltz, A. E. M. 2001. Butterfly response to pon-derosa pine restoration and the efficacy of butter-flies as indicators of pollinators. Ph.D. dissertation,Northern Arizona University, Flagstaff.Waltz, A. E. M., and W. W. Covington. 1999.Butterfly richness and abundance increase inrestored ponderosa pine ecosystem (Arizona).Ecological Restoration 17:244–246.Ecological Restoration InstituteNorthern Arizona UniversityP.O.Box 15017Flagstaff,AZ 86011-5017www.eri.nau.edu2ERI 35AENON-PROFITORG.U.S.POSTAGEPAIDNORTHERNARIZONAUNIVERSITY

Working Paper 06: Butterflies as Indicators of Restoration Progress

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