Journey North - Monarch Butterfly and Milkweed observations by volunteer community scientists across Central and North America (1996-2020)

This data package contains monarch migration data (1996 - 2020) across North America collected by 42,518 community scientists for Journey North, a crowdsourced participatory science program of the University of Wisconsin-Madison Arboretum. The Journey North Monarch and Milkweed project is an ongoing study of monarch migration phenology conducted at broad spatial and temporal scales. Since 1996, community scientists have tracked first arrival dates and breeding and feeding behavior as well as the onset of fall migration, fall roosts, and peak migration events. Community scientists have also tracked the first emergence of milkweed in the spring and the presence of milkweed across the landscape during the summer, fall-winter months. The focal species is the Monarch Butterfly, Danaus plexippus. Community scientists indicate when known milkweed species in submitted comments. Journey North data is observational and often opportunistic in nature. Observers do provide estimates of the number of adult monarch butterflies sighted during an observation. However, observers do not follow standardized methods for counting species observed. Observers do not observe at set times of the day; do not repeat observations regularly, and are not required to provide the length of time during which a specified number of species observed were counted. Therefore, it is recommended that this dataset be analyzed to indicate presence, not abundance. Additional contextual information is provided as text in the comments field of the dataset. The Journey North Monarch and Milkweed project dataset is hosted by the University of Wisconsin-Madison Shared Web Hosting Service.本数据包涵盖1996年至2020年北美地区的帝王蝶迁徙观测数据，该数据由42518名公民科学家为威斯康星大学麦迪逊分校植物园的众包参与式科学项目Journey North采集。Journey North帝王蝶与马利筋项目（Journey North Monarch and Milkweed project）是一项在跨区域、长时序尺度上持续开展的帝王蝶迁徙物候学研究。自1996年起，公民科学家们持续追踪帝王蝶的首次抵达日期、繁殖与取食行为，以及秋季迁徙启动、秋季集群栖息与迁徙高峰事件的发生时间。此外，他们还记录了春季马利筋的首次萌发情况，以及夏、秋冬两季全域范围内马利筋的分布状况。本数据集的核心观测物种为帝王蝶（Danaus plexippus），公民科学家会在提交的备注信息中注明其所观测到的马利筋物种。Journey North的观测数据属于观测性数据，且大多为偶遇式采集。观测者会对单次观测中发现的成年帝王蝶数量进行估算，但并未遵循统一的物种计数标准。观测者未在固定时段开展观测，也未定期重复观测，且无需提供统计指定观测物种数量的持续时长。因此，建议对本数据集仅开展存在性分析，而非种群丰度分析。数据集的备注字段中附带了额外的上下文文本信息。本Journey North帝王蝶与马利筋项目数据集由威斯康星大学麦迪逊分校共享网络托管服务（University of Wisconsin-Madison Shared Web Hosting Service）托管。