Characterizing New Wintering Sites for Monarch Butterfly Colonies in Sierra Nevada, Mexico

Abstract

Every year, Danaus plexippus (Linnaeus, 1758) travels to hibernate in oyamel fir forests located between the limits of the states of Michoacán and Mexico in Mexico. Climate change and anthropogenic actions are diminishing oyamel fir forests in Mexico, putting pressure on the habitats of monarch butterflies. In the last decade, new colonies outside their usual range have been predicted through modeling and reported by the National Commission on Protected Areas of Mexico. The objectives of the study were to recover information on the historical and new hibernation sites, reported or modeled, from different literature sources. We also aimed to perform a bioclimatic and forest biometric characterization of new monarch butterfly colonies located in Sierra Nevada in Mexico to provide information to aid in conservation strategies for the monarch butterfly population. We conducted field trips to georeference the colonies at sites located in the Atlautla municipality in Mexico State. Climatic, topographic, and forest biometric variables were used to characterize the sites physically. It was found that the butterfly’s roosts occurred at a higher elevation than those recorded by other sources. The locations where the monarch’s colonies were established, in the east of Mexico State, provide information relevant to defining and developing policies for their conservation.

Lack of evidence for a fine‐scale magnetic map sense for fall migratory Eastern North American monarch butterflies (Danaus plexippus)

“…Geomagnetic parameters (declination and total intensity) showed mean yearly shifts in different directions and magnitudes that would be sufficient to alter yearly overwintering abundance at the current overwintering sites (Figure 3 ). While bioclimatic models have shown new, potential regions of interest where monarchs have been recently found (Perez‐Miranda et al, 2020 ; Rendón‐Salinas et al, 2019a , 2019b ; Vidal & Rendón‐Salinas, 2014 ), the fact that these potential sites are south of the change in geomagnetic parameters supports the lack of an inherited geomagnetic map as these parameters have been shifting northwards and westwards annually and in other directions over longer time periods.…”

“…The results from this natural displacement study are inconsistent with fall Eastern North American monarchs possessing a long‐term (i.e., relatively fixed) inherited innate magnetic map sense to locate the same overwintering sites in Mexico year after year (Figure 2 ). Over the past decade, researchers have searched and registered the presence of overwintering sites in other areas in Mexico to monitor the overwintering monarch population, especially any outside the typical overwintering area, for example, the Monarch Butterfly Biosphere Reserve (Perez‐Miranda et al, 2020 ). In contrast to tracking changes in the geomagnetic signature, all new sites that have been located are to the southeast of the typical overwintering area (Perez‐Miranda et al, 2020 ), in direct contrast to changes in the geomagnetic field.…”

“…Over the past decade, researchers have searched and registered the presence of overwintering sites in other areas in Mexico to monitor the overwintering monarch population, especially any outside the typical overwintering area, for example, the Monarch Butterfly Biosphere Reserve (Perez‐Miranda et al, 2020 ). In contrast to tracking changes in the geomagnetic signature, all new sites that have been located are to the southeast of the typical overwintering area (Perez‐Miranda et al, 2020 ), in direct contrast to changes in the geomagnetic field.…”

“…The total area (ha) is used as an estimate of relative yearly abundance (Calvert & Brower, 1986 ; Slayback et al, 2007 ; Vidal et al, 2014 ; Vidal & Rendón‐Salinas, 2014 ). While newer sites have been located recently (Perez‐Miranda et al, 2020 ; Rendón‐Salinas et al, 2019a , 2019b ; Vidal & Rendón‐Salinas, 2014 ), we examined data from 2004 to 2018 for 12 sites that have been consistently sampled every year since 2004: Sierra El Campanario, Cerro Altamirano, Palomas, San Francisco Oxtotilpan, Piedra Herrada, San Andres, Mil Cumbres, Sierra Chincua, Lomas de Aparicio, Las Palomas La Mesa, Sierra Chivati‐Huacal, and Cerro Pelon (Rendón‐Salinas & Galindo‐Leal, 2004 ; Rendón‐Salinas et al, 2005 , 2006 , 2007 , 2008 , 2009 , 2011 , 2014 , 2015 , 2016 , 2017 , 2018 ; Rendón‐Salinas et al, 2010 ; Rendón‐Salinas & Tavera‐Alonso, 2012 , 2013 ). We used the earliest estimate in cases where butterflies were sampled multiple times in one year.…”

Opposing Effects of Ceanothus velutinus Phytochemistry on Herbivore Communities at Multiple Scales

“…This study was conducted outside the host range of Nymphalis californica (California Tortoiseshell) [41], one of the predominant lepidopteran predators of C. velutinus [39], which can cause heavy defoliation during outbreaks. However, anthropogenic climate change may force N. californica into new host ranges as has been observed for Danaus plexippus [65]. By establishing baseline parameters for the herbivore populations and the phytochemistry of C. velutinus communities pre-range expansion, we can better understand which chemical, biotic, and abiotic factors contribute to site selection.…”