3 years ago




INTRODUCTION The charismatic monarch butterfly is an irreplaceable piece of the natural heritage of North America. Yet this butterfly, that was once common across the country, is now plummeting toward extinction and needs protection or is at risk of being lost forever. The monarch has played a unique and prominent role in the imagination of our country, especially so for an insect. Millions of school children have reared monarchs in classrooms and learned about metamorphosis by watching the caterpillars transform. Monarchs are pivotal in science education and provide a textbook example of the principle of co-evolution and mimicry due to their complex relationship with milkweeds, their sole host plants, and with viceroy butterflies (Limenitis archippus), which are mutual mimics with monarchs, helping both butterflies avert predation. Monarchs have been reared on the international space station and were the first butterflies to have their genome sequenced. They are the official state butterfly of no less than seven states. For generations of Americans and Canadians, these large orange and black butterflies have been symbols of summer time outdoors and have served as ambassadors of nature in people’s backyards and gardens. In Mexico, the arrival of monarchs heralds Day of the Dead celebrations, and the beginning of winter. No other butterfly species on Earth undertakes a migration like the North American monarch. The multi-generational migration of the monarch butterfly can cover thousands of miles and is often described as spectacular, mysterious, and extraordinary. In late summer the butterflies begin their journey from Canada and northern states to the mountains of central Mexico or the coast of California where they will overwinter. The following spring that same generation of butterflies will return north to lay eggs on milkweed plants. Those eggs hatch into caterpillars, which feed on milkweeds, and transform into butterflies that continue to fly north in search of newly emerging milkweeds. This process is repeated for several generations, until the last generation—the “great-great-grandchildren” of the butterflies that departed overwintering sites the previous spring—returns to winter roosts the following autumn. Scientists are still trying to understand exactly how monarchs—multiple generations later—find their way to the very same winter roosts that hosted their ancestors. Visitation of overwintering monarch groves is of economic value in California and in Mexico, where such tourism is an important source of revenue for rural communities. Monarchs are important not only educationally and scientifically, but also within the ecosystem. The monarch plays a valuable role in the food web. Despite the toxins they accumulate from milkweeds, monarchs provide food for overwintering migratory songbirds, especially for orioles, grosbeaks, and towhees. Many invertebrate animals prey on monarch eggs and caterpillars including numerous species of ants, spiders, beetles, true bugs, lacewings, and wasps. Overwintering adults also provide food for small mammals in the forest. Monarchs visit many different species of flowers to drink nectar and probably act as incidental pollinators in many cases. While the monarch’s contribution to plant pollination has not been well studied, it may play an important role in the long distance transfer of pollen for some plants, and, due to its historical abundance, its contribution to the pollination of some plants may be significant. Monarch ESA Petition 12

The monarch was very recently a highly abundant species, and its population reduction indicates environmental change on a large and rapid scale. The factors that are causing monarch numbers to plummet also threaten many other species of butterflies and bees, which in turn threatens the wellbeing of people because the food security of humans is dependent on the ecological services that pollinators provide. In their overwintering groves there were once so many monarchs that the sound of their fluttering wings was commonly described as a rippling stream or a summer rain. Early newspaper descriptions of monarchs gathered on trees in California described branches breaking under the weight of so many butterflies, and depicted the masses of butterflies as “the personification of happiness” (in Lane 1993, p. 341). As recently as the winter of 1996-1997 the number of monarchs from east of the Rockies alone was estimated at around one billion butterflies. In the course of less than 20 years, that number has fallen to fewer than 35 million monarchs, representing a decline of 97 percent from the 1996-1997 high and a 90 percent decline from the 20-year average. The number of monarchs that overwinter west of the Rockies has also undergone a dramatic recent decline of 90 percent from the 1997 high (when monitoring began) and a 51 percent decline from the 17-year average. Numerous landscape-level factors have contributed to the decline of the monarch and pose ongoing threats to its continued existence. The monarch is entirely dependent on milkweeds in its summer breeding range, and milkweed availability has been drastically reduced as a result of the increased spraying of herbicides caused by the widespread planting of geneticallyengineered, herbicide-resistant crops, as predicted over a decade ago (Brower 2001). Milkweed loss has been exacerbated by the push for increased biofuel production and the planting of millions of acres of land formerly in the Conservation Reserve Program or other milkweedcompatible land uses with genetically-engineered, herbicide-resistant corn and soybean crops. Monarch overwintering habitat is threatened by development in California and by illegal logging in Mexico. Monarchs are further threatened by pesticide use, drought and other severe weather events, and climate change. Monarchs are also threatened by disease, predation, and overutilization, all of which are exacerbated by other stressors. The total population of monarchs in North America is now approximately 35 million butterflies, which could be misinterpreted to mean that the butterfly is not threatened with extinction. That millions of monarchs still survive, however, does not indicate that the species is secure. While rare species with narrow ranges are often given conservation priority, common species that face multiple environmental stressors, such as those impacting the monarch, can undergo unanticipated rapid decline or extirpation. Monarchs face multiple, synergistic, complex threats that have contributed to an extreme and rapid reduction in population size. Moreover, monarch life history strategy requires a very large population size to compensate for high levels of predation and mortality from multiple factors. It would be unwise to assume that the monarch is too common to be threatened with extinction. There is a distressing record of the rapid and unexpected decline of once common and widespread species. Examples of extremely abundant species that plummeted to unforeseen extinction include the passenger pigeon (Ectopistes simigratorius) and the Rocky Mountain Monarch ESA Petition 13

Parks for Monarchs
Increasing the availability of native milkweed - Monarch Lab
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Monarch Financial Holdings, Inc. 2009 Annual Report - Monarch Bank
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Figure 45.0 A monarch butterfly just after emerging from its cocoon
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