Pismo Beach帝王蝶林越冬季开启：蝶群栖满桉树枝头，免费参观至明年2月
位于美国加利福尼亚州圣路易斯奥比斯波县 Pismo Beach 市的 Pismo 州立海滩帝王蝶林（Pismo State Beach Monarch Butterfly Grove），11月起进入越冬蝶季，将持续至明年2月。据加州州立公园局官网，这片蝶林是公共拥有、受保护的西部帝王蝶越冬地，通常拥有全加州最大的西部帝王蝶越冬种群之一。
西部帝王蝶夏季最北可到加拿大，入冬后飞往加州海岸越冬，一天可飞行约200英里，有的迁徙距离达2,000英里；来到蝶林越冬的，已是去年越冬蝶群的第四代后代。它们成群栖息在高大的桉树和蒙特雷柏树枝头，靠树冠遮蔽风寒、保持温度稳定，林边原生花卉花园则为成蝶提供花蜜。
州立公园局同时提醒，帝王蝶种群正受到威胁，近期计数比25年前下降了约90%，越冬地流失、迁徙沿途乳草减少、极端天气、干旱与气候变化都是原因。参观时请留意脚下、不要踩到落在地上的蝴蝶，走指定步道，不要惊扰蝶群，也不要触碰或拿起帝王蝶。
据 Pismo Beach 市旅游局，蝶林位于1号公路旁的 445 South Dolliver Street，在 Pismo Beach 与 Grover Beach 两市之间，免费参观；蝶季高峰期的周末中午有讲解员现场导览（视讲解员排班与天气而定），观赏高峰通常出现在12月至1月。该市今秋还新设了全长1.1英里的「帝王蝶纪念章步道」，以一串帝王蝶标志牌把 Pismo Beach 码头与蝶林连了起来。
Monarch Season Opens at Pismo Beach Grove: Western Monarchs Cluster in the Eucalyptus Trees, Free to Visit Through February
The Pismo State Beach Monarch Butterfly Grove, in the city of Pismo Beach in San Luis Obispo County, California, enters its overwintering season in November, running through February. According to California State Parks, the grove is a publicly owned, protected overwintering site for western monarch butterflies and generally hosts one of the largest overwintering western monarch populations in California.
Western monarchs spend summers as far north as Canada and fly to the California coast for the winter, traveling as much as about 200 miles a day, with some journeys reaching 2,000 miles; the butterflies arriving at the grove are four generations removed from last year's overwintering monarchs. They cluster on the branches of tall eucalyptus and Monterey cypress trees, whose canopy buffers wind and cold and keeps temperatures stable, while a native flowering garden next to the grove provides nectar.
California State Parks notes that the monarch population is threatened: recent counts show a 90 percent drop from counts done 25 years ago, driven by the loss of coastal overwintering sites, the loss of milkweed along migration corridors, extreme weather, drought and climate change. Visitors are asked to watch for butterflies on the ground, stay on designated paths, not disturb the clusters, and not touch or handle monarchs.
According to the City of Pismo Beach visitor bureau, the grove is located at 445 South Dolliver Street off Highway 1, between Pismo Beach and Grover Beach, and is free to visit. Docent talks are offered at noon on weekends during peak season, depending on docent availability and weather, and peak viewing usually comes in December and January. This fall the city also opened the 1.1-mile Monarch Butterfly Medallion Trail, a signed coastal route linking the Pismo Beach Pier to the grove.
来源：GSM·美国（原文链接）
图片来源：栖息在Pismo Beach帝王蝶林桉树枝上的帝王蝶群。美国鱼类与野生动物管理局西南太平洋区摄，公共领域，经Wikimedia Commons。 / A cluster of monarch butterflies roosting on a eucalyptus branch at the Pismo Beach Monarch Butterfly Grove. Photo by the U.S. Fish and Wildlife Service Pacific Southwest Region, public domain, via Wikimedia Commons.
GSM Global · 本篇英文版 English edition of this story
