Raúl R. Zubieta

Bio: Raúl R. Zubieta is an academic researcher from National Autonomous University of Mexico. The author has contributed to research in topics: Monarch butterfly & Land tenure. The author has an hindex of 5, co-authored 6 publications receiving 331 citations.

Decline of monarch butterflies overwintering in Mexico: is the migratory phenomenon at risk?

Abstract: During the 2009-2010 overwintering season and following a 15-year downward trend, the total area in Mexico occupied by the eastern North American population of overwintering monarch butterflies reached an all-time low. Despite an increase, it remained low in 2010-2011. 2. Although the data set is small, the decline in abundance is statistically signifi- cant using both linear and exponential regression models. 3. Three factors appear to have contributed to reduce monarch abundance: degra- dation of the forest in the overwintering areas; the loss of breeding habitat in the Uni- ted States due to the expansion of GM herbicide-resistant crops, with consequent loss of milkweed host plants, as well as continued land development; and severe weather. 4. This decline calls into question the long-term survival of the monarchs' migra- tory phenomenon. Resumen. 1. Durante la temporada invernal 2009-2010, y siguiendo una tenden- cia a la baja de 15 anos, la superficie total ocupada por mariposas monarca en Mexico, provenientes del este America del Norte, llegoa su punto mas bajo. A pesar de su incremento, dicha superficie siguiosiendo baja en 2010-2011. 2. Aunque que el conjunto de datos disponibles es aun pequeno, esta disminucion de la abundancia de mariposas es estadisticamente significativa, tanto si se usan modelos de regresion lineales como exponenciales. 3. Hay tres factores que parecen haber contribuido con esta tendencia de reduc- ciond el numero de mariposas: la degradacion de bosque en las areas de invernacion en Mexico; la perdida de habitat de reproduccion en los Estados Unidos, debido a la expansiond e cultivos geneticamente modificados resistentes a herbicidas, con la consiguiente perdida de las plantas hospederas de algodoncillo, y por continuos cambios en el uso del suelo no favorables para ellas; y, las recientes condiciones cli- maticas severas. 4. Esta disminucion hace que nos cuestionemos sobre la posibilidad de superviven- cia a largo plazo del fenomeno migratorio de las mariposas monarca.

Oyamel fir forest trunks provide thermal advantages for overwintering monarch butterflies in Mexico

Abstract: Survivalofoverwinteringmonarchbutterfliesfollowingseverewetwin- terstormsinMexicoissubstantiallyhigherforbutterfliesthatformclustersontheoya- melfirtreetrunksthanforthosethatformclustersonthefirboughs. 2. Thermal measurements taken at similar elevations with a weather station on the SierraChincuaandwithinaCerroPelonandaSierraChincuaoverwinteringareaindicated thatclusteringonthefirtrunksprovidesdualmicroclimaticbenefitsforthebutterflies. a. At night, the minimum surface temperatures of all firs combined averaged 1.4 ! C warmer than ambient forest temperatures, thereby enhancing protection against freezing formonarchsthatareeitherwetordry.Wetermthisthe'hotwaterbottleeffect.' b. During the day, the maximum surface temperatures of all firs combined averaged 1.2! Ccoolerthanambient,adifferencesufficienttolowerthelossofthebutterflies'lipid storesoverthe154-daywinteringseason. 3. Larger diameter trees increase both microclimate benefits. 4. Theresultsaddanewdimensiontoimprovingtheconservationmanagementguide- lines for the Monarch Butterfly Biosphere Reserve. Strict enforcement against culling of largertreesandinfavourofpromotingold-growthoyamelforestswillenhancetwomicro- climatic benefits: butterfly mortality during severe winterweatherwill be reduced, and the butterflies'lipidsavingsoverthewinterwillbeenhanced.

Monarch butterfly clusters provide microclimatic advantages during the overwintering season in mexico

Abstract: Monarch butterflies form dense clusters in their overwintering colonies in the mountains of central Mexico, where forest cover provides protection from environmental extremes. We tested the hypothesis that the clustering behavior of the butterflies further moderates the microclimate they experience. We inserted hygrochrons (miniaturized digital hygrothermographs) into clusters for two-day periods during the 2006-07 and 2007-08 winters and compared temperature and relative humidity inside and outside the clusters. The inside of the clusters re- mained significantly warmer at night and significantly cooler during the day, with higher relative humidity during both day and night. Conse- quently, the butterflies inside the clusters may have gained some protection from freezing, reduced their rate of lipid burning, and lowered their rate of desiccation. The differences were small, but these studies were conducted during calm, moderate conditions, and the effects are likely to be more pronounced under more severe weather, including mid-winter storms and late season aridity. The microclimatic advantages of the monarchs' clustering behavior on fir boughs add to the known repertoire of the butterflies' overwintering adaptations to the high altitude envi- ronment that they occupy each year from November through March.

Overwintering Clusters of the Monarch Butterfly Coincide with the Least Hazardous Vertical Temperatures in the Oyamel Forest

Abstract: . During winter, monarch butterflies form dense colonies in oyamel fir forests on high mountains in central Mexico, where the forest canopy serves both as a blanket, moderating temperature, and an umbrella, shielding the butterflies from rain. In this study we investigated the vertical dimension of the butterflies' use of the oyamel forest: we predicted that clusters form at the heights above ground that provide the greatest protection from freezing. By suspending temperature recorders at eight heights, from ground level up to 22m, we established two vertical transects in the forest. We set one transect in a densely forested area and the other in a thinned area, and we recorded hourly temperatures from Jan 13 through Feb 5, 2006. Intermediate heights in the forest, from 10 to 15m above ground, remained the warmest during the cold night and early morning. We also determined that this temperature distribution matched available records of the vertical distribution of butterflies roosting in branch an...

Land Cover and Road Network Map for the Monarch Butterfly Biosphere Reserve in Mexico, 2003

Abstract: Please click here to download the map associated with this article. To preserve the monarch butterfly (Danaus plexippus L.) overwintering sites in Mexico, the fir forests used for the main colonies have been protected by three presidential decrees, in 1980, 1986 and 2000. The territory of the current Monarch Butterfly Biosphere Reserve (MBBR) belongs mainly to communal properties (ejidos and indigenous communities). Contrary to expectation, this protected area is still facing severe disturbance and loss of forest cover, because of intensive illegal and legal logging, and subsistence farming activities. Roads are landscape elements well known as a cause of disturbance and deforestation. Therefore, the aim of this map is to illustrate the road network and land cover relationship in the MBBR, taking into account the land tenure. The roads vector layer was obtained by photointerpretation of one meter resolution digital aerial photograph mosaics from March 2003, and one meter resolution Ikonos panshar...

Insect Declines in the Anthropocene

Abstract: Insect declines are being reported worldwide for flying, ground, and aquatic lineages. Most reports come from western and northern Europe, where the insect fauna is well-studied and there are consi...

Milkweed loss in agricultural fields because of herbicide use: effect on the monarch butterfly population

Abstract: The size of the Mexican overwintering population of monarch butter- flies has decreased over the last decade. Approximately half of these butterflies come from the U.S. Midwest where larvae feed on common milkweed. There has been a large decline in milkweed in agricultural fields in the Midwest over the last decade. This loss is coincident with the increased use of glyphosate herbicide in conjunction with increased planting of genetically modified (GM) glyphosate-tolerant corn (maize) and soybeans (soya). 2. We investigate whether the decline in the size of the overwintering population can be attributed to a decline in monarch production owing to a loss of milkweeds in agricultural fields in the Midwest. We estimate Midwest annual monarch production using data on the number of monarch eggs per milkweed plant for milkweeds in dif- ferent habitats, the density of milkweeds in different habitats, and the area occupied by those habitats on the landscape. 3. We estimate that there has been a 58% decline in milkweeds on the Midwest landscape and an 81% decline in monarch production in the Midwest from 1999 to 2010. Monarch production in the Midwest each year was positively correlated with the size of the subsequent overwintering population in Mexico. Taken together, these results strongly suggest that a loss of agricultural milkweeds is a major contributor to the decline in the monarch population. 4. The smaller monarch population size that has become the norm will make the species more vulnerable to other conservation threats.

Long-range seasonal migration in insects: mechanisms, evolutionary drivers and ecological consequences

Abstract: Myriad tiny insect species take to the air to engage in windborne migration, but entomology also has its ‘charismatic megafauna’ of butterflies, large moths, dragonflies and locusts. The spectacular migrations of large day-flying insects have long fascinated humankind, and since the advent of radar entomology much has been revealed about high-altitude night-time insect migrations. Over the last decade, there have been significant advances in insect migration research, which we review here. In particular, we highlight: (1) notable improvements in our understanding of lepidopteran navigation strategies, including the hitherto unsuspected capabilities of high-altitude migrants to select favourable winds and orientate adaptively, (2) progress in unravelling the neuronal mechanisms underlying sun compass orientation and in identifying the genetic complex underpinning key traits associated with migration behaviour and performance in the monarch butterfly, and (3) improvements in our knowledge of the multifaceted interactions between disease agents and insect migrants, in terms of direct effects on migration success and pathogen spread, and indirect effects on the evolution of migratory systems. We conclude by highlighting the progress that can be made through inter-phyla comparisons, and identify future research areas that will enhance our understanding of insect migration strategies within an eco-evolutionary perspective.

Global buffering of temperatures under forest canopies

Abstract: Macroclimate warming is often assumed to occur within forests despite the potential for tree cover to modify microclimates. Here, using paired measurements, we compared the temperatures under the canopy versus in the open at 98 sites across 5 continents. We show that forests function as a thermal insulator, cooling the understory when ambient temperatures are hot and warming the understory when ambient temperatures are cold. The understory versus open temperature offset is magnified as temperatures become more extreme and is of greater magnitude than the warming of land temperatures over the past century. Tree canopies may thus reduce the severity of warming impacts on forest biodiversity and functioning.