Dynamics and trends of overwintering colonies of the monarch butterfly in Mexico

There are two breeding migratory populations of the monarch butterfly (Danaus plexippus) in North America. A comparatively small, Western population migrates from states west of the Rocky Mountains to California, and a large Eastern population migrates from southern Canada and the United States to central Mexico. We monitored the dynamics and trends of monarch overwintering colonies in Mexico from the 2004–2005 to the 2013–2014 seasons. Of 19 colonies, 14 were inside the Monarch Butterfly Biosphere Reserve and five were outside the reserve. The number of colonies with butterflies varied among years, and in only three colonies were butterflies consistently present in all seasons. The total cumulative area of forest used by all monarch colonies in all seasons was 106.53 ha: 83.68% inside the reserve and 16.32% outside the reserve. By the 2013–2014 season, however, the surface occupied by monarchs (0.67 ha) had decreased 44% from the previous season, and is the smallest in two decades, far from the highest record of 18.19 ha in the 1996–1997 season. Extensive loss of breeding habitat by eradication of common milkweed (Asclepias syriaca, the primary food source for monarchs) from herbicide use and land-use changes in the United States, extreme climate conditions in Canada, the United States and Mexico, and deforestation and forest degradation in overwintering sites in Mexico all contributed to the steady decline in the abundance of monarch butterflies. Unregulated tourism also has become a threat to the dwindling colonies in Mexico. Protection of overwintering sites in Mexico is crucial to conserve this butterfly in North America. Given the rapid decline of monarch overwintering sites documented here, it is critical to initiate an immediate and concerted effort to protect and restore habitat along the migratory routes in the three countries. 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

[1]  J. Pleasants,et al.  Milkweed loss in agricultural fields because of herbicide use: effect on the monarch butterfly population , 2013 .

[2]  Lincoln P. Brower,et al.  Catastrophic Winter Storm Mortality of Monarch Butterflies in Mexico during January 2002 , 2007 .

[3]  K. Hobson,et al.  DO NORTH AMERICAN MONARCH BUTTERFLIES TRAVEL TO CUBA? STABLE ISOTOPE AND CHEMICAL TRACER TECHNIQUES , 2004 .

[4]  A Townsend Peterson,et al.  Ecological Niches in Sequential Generations of Eastern North American Monarch Butterflies (Lepidoptera: Danaidae): The Ecology of Migration and Likely Climate Change Implications , 2007, Environmental entomology.

[5]  Luis A. Bojórquez-Tapia,et al.  Quantitative Changes in Forest Quality in a Principal Overwintering Area of the Monarch Butterfly in Mexico, 1971–1999 , 2002 .

[6]  B. Taylor,et al.  Gray whale Eschrichtius robustus population and stock identity , 2006 .

[7]  R. Ostfeld,et al.  Climate Warming and Disease Risks for Terrestrial and Marine Biota , 2002, Science.

[8]  L. Brower,et al.  THE LOCATION OF MONARCH BUTTERFLY DANAUS-PLEXIPPUS L. OVERWINTERING COLONIES IN MEXICO IN RELATION TO TOPOGRAPHY AND CLIMATE , 1986 .

[9]  Seth M. Barribeau,et al.  Lack of genetic differentiation between monarch butterflies with divergent migration destinations , 2012, Molecular ecology.

[10]  Thomas H. Kunz,et al.  Bat Biology and Conservation , 1998 .

[11]  L. Brower,et al.  Time, temperature, and latitudinal constraints on the annual recolonization of eastern North America by the monarch butterfly , 1993 .

[12]  R. Vane‐Wright,et al.  Milkweed Butterflies: Their Cladistics and Biology , 1984 .

[13]  J. López-García,et al.  Trends in Deforestation and Forest Degradation after a Decade of Monitoring in the Monarch Butterfly Biosphere Reserve in Mexico , 2014, Conservation biology : the journal of the Society for Conservation Biology.

[14]  Martin Wikelski,et al.  Going, Going, Gone: Is Animal Migration Disappearing , 2008, PLoS biology.

[15]  Bruno S. Frey,et al.  World Heritage List , 2013 .

[16]  L. Brower,et al.  USE OF LIPID RESERVES BY MONARCH BUTTERFLIES OVERWINTERING IN MEXICO: IMPLICATIONS FOR CONSERVATION , 1997 .

[17]  Margaret Savanick Guiney,et al.  Insects as flagship conservation species , 2009 .

[18]  Michael B. Wunder,et al.  Tracking multi-generational colonization of the breeding grounds by monarch butterflies in eastern North America , 2013, Proceedings of the Royal Society B: Biological Sciences.

[19]  D. Slayback,et al.  Decline of monarch butterflies overwintering in Mexico: is the migratory phenomenon at risk? , 2012 .

[20]  L. Brower.  Understanding and misunderstanding the migration of the monarch butterfly (Nymphalidae) in North America: 1857-1995 , 1995 .

[21]  K. Hobson,et al.  Migratory Connectivity of the Monarch Butterfly (Danaus plexippus): Patterns of Spring Re-Colonization in Eastern North America , 2012, PloS one.

[22]  Karen S. Oberhauser,et al.  The Monarch Butterfly: Biology and Conservation , 2004 .

[23]  R. Anderson.  Do dragonflies migrate across the western Indian Ocean? , 2009, Journal of Tropical Ecology.

[24]  Lincoln P. Brower,et al.  Animal Migrations: Endangered Phenomena , 1991 .

[25]  S. Altizer,et al.  The genetics of monarch butterfly migration and warning coloration , 2014, Nature.

[26]  D. Slayback,et al.  Establishing the Presence and Absence of Overwintering Colonies of the Monarch Butterfly in Mexico by the Use of Small Aircraft , 2007 .

[27]  D T Tyler Flockhart,et al.  Unravelling the annual cycle in a migratory animal: breeding-season habitat loss drives population declines of monarch butterflies. , 2015, The Journal of animal ecology.

[28]  M. Zalucki,et al.  Biology and conservation of the monarch butterfly , 1997 .

[29]  Optimism and Challenge for Science‐Based Conservation of Migratory Species in and out of U.S. National Parks , 2014, Conservation biology : the journal of the Society for Conservation Biology.

[30]  A. Peterson,et al.  Modeling current and future potential wintering distributions of eastern North American monarch butterflies , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[31]  E. Culotta.  The case of the missing monarchs. , 1992, Science.

[32]  L. Brower,et al.  The Effect of Rain, Snow and Freezing Temperatures on Overwintering Monarch Butterflies in Mexico , 1983 .

[33]  F. A. Urquhart,et al.  OVERWINTERING AREAS AND MIGRATORY ROUTES OF THE MONARCH BUTTERFLY (DANAUS P. PLEXIPPUS, LEPIDOPTERA: DANAIDAE) IN NORTH AMERICA, WITH SPECIAL REFERENCE TO THE WESTERN POPULATION , 1977, The Canadian Entomologist.

[34]  F. A. Urquhart.  Found at last: the monarch's winter home , 1976 .

[35]  S. Altizer,et al.  Associations between host migration and the prevalence of a protozoan parasite in natural populations of adult monarch butterflies , 2000 .