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The U.S. state of California has instituted numerous conservation programs, policies, laws, reserves and Habitat restoration projects throughout the state to facilitate the health and migration of the western population of the monarch butterfly (''Danaus plexippus''). The population of western monarchs require very different breeding and overwintering habitat when compared to the eastern population of monarch butterflies. They require specific micro-climatic conditions to survive the winter and they are sensitive to habitat changes at the overwintering sites. The large aggregations of butterflies are seen as the most vulnerable at their overwintering locations along the coast. Many monarch overwintering sites are contained within the "coastal zone”; an area defined by the Coastal Zone Management Act〔(【引用サイトリンク】publisher=United States FWS ) 〕 to be 1000 yards inland from the high tide mark. Large number of overwintering sites are outside the coastal zone. There are more than 450 overwintering sites in California documented since the 1980s. The location of some sites makes it difficult to determine whether it was located on private land or, public land. == Protection of trees and habitat == Conservationists promote habitat conservation by identifying trees that are necessary for roosting. They suggest that roosting sites be identified and designed to prevent degradation of the area. They also suggest that an environmental impact statement be filed when construction is done near overwintering roasts. Removal of trees within the perimeter of the habitat should be prohibited. Tree maintenance should be performed by experts in the field. They propose that it should be unlawful to remove trees, under-story plants and vegetation near roosting sites. Reforestation efforts should be instituted. Erosion control needs to be taken into account to maintain suitable habitat. Conservationists suggest that wood-burning fireplaces and structures should not be built near roosting sites. One conservation group, the International Environmental Law project issued a policy statement regarding eucalyptus management at Monarch overwintering sites. This group recognizes the wide variety of tree species that monarchs utilize in their overwintering roosts. The Xerxes society recommends that eucalyptus trees remain unmolested, if monarchs roost on the trees. 〔 (【引用サイトリンク】 url = http://www.pdfdrive.net/download-pdf-the-xerces-society-e7530633.html ) 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Monarch butterfly conservation in California」の詳細全文を読む スポンサード リンク
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