Abstracts

CHASING WESTERN MONARCHS: NEW VIEWS ON MIGRATION ROUTES
Robert M. Pyle, The Xerces Society, 4828 SE Hawthorne Blvd., Portland, OR 97215

The notion of a bipartite monarch migration divided by the Rocky Mountains has long been a cherished part of the North American natural history canon. In fact, the data for such a complete division are almost non existent, and depend mostly upon misleading transfer/release/recapture exercises. An effort to physically follow one part of the 1996 autumn movement in the West, and to tag emigrants, suggested a revised model for the western migration. Potential numbers and destinations of western monarchs entering Mexico instead of California will be discussed, along with conservation implications of the new information. Transfer and release of monarchs in the West subverts an accurate understanding of the species' biogeography.

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DEVELOPMENT OF PROTOCOLS FOR LONG-TERM HABITAT MANAGEMENT OF OVERWINTERING SITES IN CALIFORNIA
Kingston L. H. Leong, Ph.D, Department of Biological Sciences
California Polytechnic State University, San Luis Obispo, CA 93407

A key component in the preservation of the mass winter aggregations of monarch butterflies' in California is through long-term habitat management of winter groves. Groves that support overwintering butterflies are dynamic changing systems and conditions that favor their winter aggregations can be easily altered by tree loss due to diseases, storm damage and urban development or by normal grove senescence. The management, of winter groves therefore, should be focus on enhancement activities aimed at maintaining or re-establishing favorable conditions for the roosting butterflies. Enhancement of winter groves should be based on data obtained from the monitoring and the evaluation of certain biological and environmental variables. These variables should include: (1) wind pattern of gusty and storm winds; (2) the butterflies' seasonal aggregation pattern within the grove; (3) their winter occupancy; (4) morning and afternoon sunlit foliage supporting roosting butterflies; and (5) sunlit areas for foraging for nectar or water and for mating.

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PROJECT MONARCH ALERT - STUDIES OF POPULATION DYNAMICS IN WESTERN NORTH AMERICA
Dennis Frey & Shawna Stevens, Biological Sciences Department
California Polytechnic State University, San Luis Obispo, CA 93407

Monarch Alert is our project name for a series of studies dealing with fall migration, wintering activity, and spring dispersal of monarch butterflies (Danaus plexippus L.) in western North America. The studies are carried out at varied spatial and temporal scales. We have employed several approaches including, among others, tagging many individuals, monitoring seasonal populations at 16 focal wintering sites in San LuisObispo and Monterey Counties, coordinating and conducting annual Thanksgiving Counts throughout these two counties, characterizing the population genetic structure of the northern half of the western wintering range, and analyzing system-wide population dynamics over a seven year history. The monitoring program has identified probable causative factors that initiate spring dispersal, as well as, local changes in habitat use that often precedes dispersal. One of the preliminary findings of the tagging program is that monarchs transferred almost exclusively to nearby sites and that movement never took place between counties. Finally, the value of multi-scale studies such as these, involving large sample sizes will be illustrated from analyses of seasonal changes in monarch body and wing condition. Two approaches will be contrasted: 1) periodic sampling of the general population and 2) tracking the condition of many tagged individuals over a finite period. Differences between these two approaches can be used to estimate the degree of phenotypic bias in dispersal and facilitate the identification of other abiotic or spatial causative factors that influence dispersal. Quantitative data provided by the Monarch Alert project will help create appropriate conservation strategies that protect this valuable natural resource.

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USING CLIMATE PATTERNS TO STUDY THE LOCAL RECRUITMENT HYPOTHESIS
Shawna Stevens, Biological Sciences Department
California Polytechnic State University, San Luis Obispo, CA 93407

Monarchs in western North America winter at over 300 sites along the Pacific Ocean coastline, from northern California down to Ensenada, Baja California. While abundance at the majority of these sites rarely exceeds 1,000 butterflies, system-wide abundance has steadily declined for the past several years. Increasing drought conditions in the west appear to be the most likely cause for declining populations. Since the last El Nino conditions in 1998, extensive areas of western North America have undergone extreme drought, which by some standards is the worst drought in the last 40 years. Dramatic declines in monarch abundance are congruent with these increasingly dry conditions. It is well known that primary production in most terrestrial systems is strongly influenced by annual precipitation levels. It follows then that these drought conditions have resulted in declining milkweed biomass at western monarch breeding grounds, which leads to lower monarch recruitment to the migratory population. Using the Palmer Drought Severity Index, we tested for a causal relationship between drought and abundance and found significant associations in several western states, including Nevada, California, and Oregon. Drought severity was not uniform within states, which also allowed tests of association at a finer geographical level. Climate data and variation in wintering abundance at this finer scale can be used to test specific hypotheses pertaining to natal origins, such as the local recruitment hypothesis. This is the notion that wintering populations derive primarily from nearby breeding ranges. The results of such hypothesis testing would strongly impact conservation strategies. While confirmation of this hypothesis would suggest a regionally focused conservation approach, rejection of the hypothesis might sway conservation efforts towards more widespread measures. These are the types of information upon which wintering habitat management and conservation guidelines should be based, and which are currently lacking for western monarch populations.

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PATTERNS OF HABITAT USE BY OVERWINTERING MONARCHS (DANAUS
PLEXIPPUS) IN MONTEREY COUNTY, CA
Nellie Thorngate and Jessica Griffiths, Ventana Wilderness Society
Big Sur Ornithology Lab, HC 67 Box 99, Monterey, CA

Monarch butterflies (Danaus plexippus) in western North America overwinter on the coast of California in groves that fit specific environmental parameters. Overwintering sites must be able to buffer Monarchs from extremes of temperature, humidity, and wind,and are typically characterized by dense groves of trees forming natural amphitheaters. We began monitoring Monarchs and their overwintering habitats at eight Monterey County sites beginning in 2001. Three groves contained a variety of tree species, including Monterey pine (Pinus radiata), Coast redwood (Sequoia sempervirens), Monterey cypress (Cupressus macrocarpa), and Eucalyptus spp. Three groves were composed of Eucalyptus, and two were comprised of Monterey pines. We examined patterns in cluster formation including cluster height and aspect, and analyzed relationships between tree species use and regional climate variables. Average cluster height was 9.02 meters. Clusters most frequently had a Southeastern orientation. We used Spearman's Rank Correlation to elucidate an observed trend toward increased use of coniferous tree species after significant storm events. The percentage of butterflies found on coniferous trees exhibited a negative correlation with temperature. Correlations between tree species use and rainfall varied between sites and years. Neither humidity nor wind speed were correlated with tree species use. We recommend that future monitoring at these overwintering sites include the collection of microclimate data from each site. Continued population and habitat monitoring coupled with the implementation of adaptive management principles at each site will ensure the long-term preservation of overwintering Monarchs in central coastal California.

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MONARCH TAGGING: WHAT TAG RECOVERIES TELL US ABOUT THE MIGRATION
Orley R. "Chip' Taylor, University of Kansas
Department of Ecology and Evolutionary Biology, 1200 Sunnyside Ave., Lawrence, KS

Monarch tagging , in which small individually coded adhesive tags are applied to the wings of monarchs by thousands of volunteers each fall, has provided new information on the dynamics of the migration. The numbers of monarchs tagged by volunteers has ranged from 40,000 to >100,000 for the last 9 years. Recovery rates of monarchs reaching Mexico range from approximately 0.5 to 3%, with higher recovery rates following winter the storms of 2002 and 2004. El Rosario, a site that hosts +/-40% of the total overwintering population, is the source of >80% of the tags. The records of 6800 monarchs recovered in Mexico have been analyzed. Within a relatively narrow longitudinal range from Minnesota through Texas, the rate of recovery is a function of distance. Recovery rates decline in a non-linear manner at longitudes east of the Midwest. Within the United States, a disproportionate number of the recoveries occur in the mid-Atlantic states. The date of tagging, across all latitudes, for all years, and of select years, shows that the migration progresses southward in a predictable pattern each year. Recovery rates are highest for monarchs tagged near the midpoint of the migration across all latitudes.

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NEW PERSPECTIVES ON MIGRATION IN MONARCH BUTTERFLIES: INSIGHTS FROM LONG-TERM MONITORING AND CITIZEN SCIENCE
Andrew K. Davis, Dept. of Environmental Studies
Emory University, 400 Dowman Dr., Atlanta, GA

In the past decade, multiple long-term monarch migration monitoring projects have been in place across eastern North America. Most are run by a combination of trained scientists, dedicated volunteers and citizen scientists. Journey North is an online program that recruits school children to track the monarch spring migration on a continent-wide scale. By comparison, more intensive monitoring programs have been established to track the fall migration of monarchs at single sites in Cape May, New Jersey, Chincoteague, Virginia, and Peninsula Point, Michigan. This talk will focus on several recent papers in print, press and review, highlighting results from each of these spring and fall projects. First, data from the Journey North program from 1997-2002 were used to document patterns of monarch recolonization of their breeding range in eastern North America. Results showed a remarkable consistency in this pattern from year to year. More recently, these data were used to generate new estimates of spring migration speed using GIS technology, pointing to distinct spring migration phases. Second, monitoring efforts focusing on fall migration through major monarch flyways provide evidence for long-term population trends, effects of environmental parameters on stopover patterns, and consistency in migration patterns among sites. At all three of the fall migration monitoring sites, volunteers count the number of monarchs seen during standardized daily censuses. At Peninsula Point, 7 years of monitoring data showed how daily environmental conditions such as wind directions affect the numbers of monarchs that stop over at the site. Thirteen years of monitoring data from Cape May documented the timing and consistency of migration waves and elucidated long-term trends in the eastern population. Results showed fluctuating annual population sizes and an alarming drop in monarch numbers during the past 4 years. Finally, data from the Chincoteague project have been recently used to show that annual indices of monarch abundance between this and the Cape May site are similar. Each of these projects provides us with critical insights into the unique and endangered phenomenon of monarch migration in eastern North America.

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DETERIORATION OF THE PRIME OVERWINTERING HABITAT IN THE MONARCH BUTTERFLY BIOSPHERE RESERVE IN MEXICO
Lincoln P. Brower, Linda S. Fink, Daniel E. Slayback, and David Perault
Biology Department, Sweet Briar College, Sweet Briar, VA. and University of Florida
Science Systems and Applications, Inc., Biospheric Sciences Branch, Code 923 NASA Goddard Space Flight Center, Greenbelt, MD,
School of Sciences, Lynchburg College, Lynchburg, VA

Aerial photography, Landsat and Ikonos satellite imagery and ground reconnaissance document that four of the principal overwintering areas of the eastern North American population of the monarch butterfly (Danaus plexippus L.) are deteriorating due to illegal logging. Several specific overwintering sites studied since 1977 have been eliminated in the Chivati-Huacal and Cerro Pelon massifs, while deleterious encroachment has occurred on the Sierra Campanario and Sierra Chincua massifs. The extent of logging in the latter area increased extensively in 2003- 2004. All of these overwintering areas were protected by Presidential decree in 1986, and by a new Presidential decree in 2000 that created The Monarch Butterfly Biosphere Reserve. The prognosis for the long term survival of the overwintering phenomenon of the monarch butterfly in Mexico is poor.

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A REMOTE-SENSING OVERVIEW OF FOREST COVER CHANGE IN THE MONARCH BUTTERFLY OVERWINTERING REGION IN MEXICO
Daniel A Slayback , Isabel Ramirez , Lincoln P. Brower, David Perault, Linda S. Fink
Science Systems & Applications, Inc., Biospheric Science Branch, Code 614.4, Goddard Space Flight Center, Greenbelt, MD.
Institute of Geography, UNAM, Mexico City, Mexico.
Biology Department, Sweet Briar College, Sweet Briar, VA.
Department of Environmental Sciences, Lynchburg College, Lynchburg, VA.

Change in the forest cover over the primary Monarch butterfly overwintering colonies in central Mexico (Michoacan and Mexico states) has become an increasingly serious and contentious issue. Logging, some of it sanctioned, but much of it illegal, occurs within the watersheds and drainages that the Monarchs have historically occupied during their overwintering period. However, there is some debate whether such logging adversely affects the Monarch habitat and colony health. As a first step in addressing these questions, we examined the available time-series of remotely sensed imagery of the area in order to quantify the landcover change dynamics over the past 40 years. Imagery from the mid-1960's (Corona; declassified US Defense Department imagery), 1970s (Landsat MSS and aerial photography), 1980s (Landsat TM and aerial photography), 1990s (Landsat ETM and aerial photography), and 2000s (Landsat ETM and Ikonos imagery) were acquired, orthorectified, and used to categorize landcover change over this period. An automated classification algorithm was used for this work; future work will attempt to validate the results with a manual interpretation-based approach. Preliminary results show substantial deforestation over this period in areas adjacent to and within the historical colony locations.

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DESIGNING THE FOREST WITH THE TREES: QUANTITATIVEASSESSMENT OF FOREST STRUCTURE FOR OVERWINTERING MONARCH BUTTERFLIES
Stuart B. Weiss, Creekside Center for Earth Observations
27 Bishop Lane, Menlo Park, CA 94025

The monarch butterfly migration phenomenon is utterly dependent on a limited number of forested overwintering sites in Mexico and California. The forest canopy structure at these sites, no matter which species of tree(s), must provide proper microclimatic conditions during the overwintering season: minimal exposure to freezing temperatures, protection from winds, and sufficient sunlight to allow for thermoregulation. This presentation describes detailed quantitative assessments of canopy structure using hemispherical photography, and derivation of temperature, wind, and sunlight exposure factors that can be mapped out at a fine scale. Assessments for short- and long-term management and restoration of sites are illustrated with Eucalyptus groves in Pacific Grove and Andrew Molera State Park, and initial results from Oyamel fir forests in Michoacan, Mexico. The habitat requirements for overwintering monarchs are understandable from a microclimatic viewpoint, and systematic, quantitative, and understandable assessments that allow for effective conservation of the phenomenon are feasible.

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MONARCH BUTTERFLIES IN CHANGING ENVIRONMENTS: PARASITES, MIGRATION, AND PHENOTYPIC VARIATION
Sonia Altizer, Department of Environmental Studies
Emory University, 400 Dowman Drive, Atlanta, GA 30322

Native and introduced monarch butterflies populate islands and continents worldwide and occupy a subset of the range of their larval host plants. Although monarchs appear morphologically similar throughout most of their range, populations do not exist in uniform environments, and selection may operate on traits affecting migratory ability, response to different host plant species, thermal tolerance, and resistance to natural enemies. In this talk, I briefly review results from recent efforts to examine variation in each of these four traits among three N. American monarch populations. First, the prevalence of a protozoan parasite (Ophyrocystis elektroscirrha) varies widely among populations, ranging from near 0 to almost 100% infection. Host resistance to parasite infection also varies among three North American populations, with highest resistance among monarchs from the eastern migratory population. Wing morphology is expected to differ in response to selection driven by long distance flight operating on some populations but not others, and data from laboratory-raised and wild-captured monarchs supports this hypothesis. Other traits likely to vary among populations are thermal tolerance, including host survival and development rates in response to different environmental temperatures, and host use traits with respect to different milkweed species. Whether or not, and to what degree phenotypic differences have accumulated among monarch populations is relevant to understanding their migratory ecology, interspecific interactions, and for predicting how monarchs might respond to future environmental changes.

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POTENTIAL EFFECTS OF CLIMATE CHANGE ON EASTERN NORTH AMERICAN MONARCH BUTTERFLY (DANAUS PLEXIPPUS) DISTRIBUTIONS
Karen Oberhauser, Reba Batalden and A. Townsend Peterson
University of Minnesota, Department of Fisheries, Wildlife and Conservation Biology, 1980 Folwell Avenue, St. Paul, MN
University of Minnesota, Department of Ecology, Evolution and Behavior, 1987 Upper Buford Circle, St. Paul, MN
University of Kansas, Natural History Museum and Biodiversity Research Center, Lawrence, KS

Monarch butterflies appear to use very restricted climatic niches during their wintering period in central Mexico, and as they breed in the northern US. We used ecological niche modeling to identify areas adequate for monarch survival under both current and future climate scenarios. This approach permits testing and validation of model predictivity, and yields quantitative, testable predictions regarding likely future climate change effects. Our models predicted monarch presence with a high degree of accuracy, and indicated that precipitation and diurnal temperature range were key environmental factors in making winter locations suitable for monarchs. When we projected monarch distribution onto future climate scenarios (using Hadley Centre climate models), we found that conditions were likely to be inadequate across the entire current winter range, particularly owing to increased cool-weather precipitation that could cause increased mortality. We have also used data from the Monarch Larval Monitoring Project (MLMP) to model effects of climate change on the monarchs' summer habitat. Preliminary results show that suitable summer habitat is likely to move northward, but will still exist in 50 years.