Project Overview
Monarch butterflies in North America have a fascinating migration and overwintering biology. It is understood that monarchs from east of the Rocky Mountains migrate to the mountains of Central Mexico and monarchs in the Western U.S. migrate to California. Monarchs in Arizona can migrate to Mexico, California, or a small number seem to spend the winter in the lower deserts of Arizona. Usually overwintering monarchs do not breed or lay eggs for the entire winter, but they do for part of the winter in Arizona. Very little is understood about this overwintering population in Arizona and the timing of overwintering and breeding. Milkweeds (plants in the genus Asclepias) are the host plants for monarch butterflies. Adult monarchs lay eggs on milkweed and their caterpillars only eat milkweed plants. There are about 30 native milkweeds in Arizona.
The USA-NPN is collaborating with Desert Botanical Garden to answer these questions:
1. Where and when are adult monarch butterflies observed across Arizona during the winter?
2. When are monarchs breeding (as evidenced by the presence of caterpillars)?
3. What life stages do milkweeds experience during the winter and how might this affect monarchs?
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How to Participate
Join Nature's Notebook and select one or more milkweeds to track, then add monarchs to your site as well. Observe leafing and flowering of milkweeds and presence and absence of monarch adults and caterpillars, ideally 2–3 times per week during fall, winter, and spring, and log your data in Nature's Notebook. Need help getting started? Take the Observer Certification Course or watch this recorded webinar.
Your data are more vauable when you track both monarchs and one or more milkweeds at your site.
Desert Refuge: Monarchs and Milkweeds in Arizona Species
- Arizona milkweed (Asclepias angustifolia)
- bloodflower (Asclepias curassavica)
- desert milkweed (Asclepias erosa)
- horsetail milkweed (Asclepias subverticillata)
- monarch (Danaus plexippus)
- pineneedle milkweed (Asclepias linaria)
- rush-desert-milkweed (Asclepias subulata)
- spider milkweed (Asclepias asperula)
Contributing Programs
Local Phenology Programs with the most observation records submitted this season.
| # | Program | Observations |
|---|---|---|
| 1 | Reid Park Zoo Pollinator Garden | 381 |
| 2 | Desert Botanical Garden | 351 |
| 3 | Master Gardeners Phenology Group | 343 |
| 4 | Tohono Chul Self-Guided Phenology Trail | 248 |
| 5 | Tucson Botanical Garden | 120 |
Research team
Kim Pegram, Desert Botanical Garden
Natalie Melkonoff, Desert Botanical Garden
The project is funded by a Partner Grant from Monarch Joint Venture and U.S. Forest Service International Programs.