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New iNaturalist Project Makes it Easier to Submit Data to the Western Monarch Milkweed Mapper

By Stephanie McKnight on 7. June 2019
Stephanie McKnight

We need all hands on deck this season, to better understand the hurdles facing the imperiled western monarch population!

As spring progresses and summer approaches, monarchs are beginning to show up across the western United States. In the past month, monarch eggs have been observed at two locations in Northern California (12 eggs in Willows, CA on showy milkweed, and 2 eggs in Grass Valley, CA on heartleaf milkweed—pictured), and adults have now been observed in Oregon, Eastern Washington, and southern Idaho.


Two photos show a small, lime-green sphere on the underside of a maroon leaf. The egg is circled to make it easier to notice, because it is quite small!
Two monarch eggs were recently observed in Grass Valley, CA on heartleaf milkweed (Asclepias cordifolia). (Photos: Xerces Society / Stephanie McKnight)


We know this thanks to the efforts of community members that have submitted data to the Western Monarch Milkweed Mapper, an online community science project that allows anyone to sign up and submit data about when and where monarchs and milkweeds occur in the West. This season, we are expanding upon this community science project and making it easier to collect and submit data. The Xerces Society and several partners have created an iNaturalist project that will link directly to the Western Monarch Milkweed Mapper.

Now you can submit data to the Western Monarch Milkweed Mapper using the iNaturalist app on a smartphone or tablet (iOS and Android are both supported). This new way of submitting data can make it easier to share photos and locality data, but it doesn’t replace the previous methods to submit data: online via the mapper website, or using the Monarch SOS app. If you are already happy submitting data using one of these methods, please feel free to keep doing that! In fact, the Monarch SOS app is still the primary app for the annual Western Monarch Thanksgiving Count and New Year Count during the overwintering period, from late October to February. The iNaturalist project, on the other hand, is intended for all non-overwintering monarch observations (generally from March-late October) and all native milkweed observations throughout the year.

This year’s western monarch overwintering population on the California coast was the lowest ever recorded by the annual Western Thanksgiving Count, representing a decline of over 99 percent compared to the population in the 1980s. Collecting data this year is crucial for understanding when and where monarchs breed in the West, providing more focus for conservation efforts. We are seeking to answer a number of questions, including: Are monarchs expanding from the desert southwest into Nevada and Idaho? Where in California will monarchs breed this year, and on what milkweed species? Will monarchs make it to Oregon and Washington? If you’re located in Arizona, California, Idaho, Nevada, Oregon, Washington, or Utah, you can help to answer these and additional research questions—no special training necessary!

Indeed, with low numbers of monarchs expected across the West this year, we need as many keen eyes as possible to find and report monarchs to the Western Monarch Milkweed Mapper, and we invite anyone with an interest in supporting the imperiled western monarch to pitch in. Thank you in advance for your contributions this season!


An orange and black monarch almost seems to sparkle in this close-up, crisp image. So many small details are captured, including a bit of the glimmering scales on the butterfly's wings!
The new Western Monarch Milkweed Mapper iNaturalist project is intended for all non-overwintering monarch observations (generally from March-late October) and all native milkweed observations throughout the year. (Photo: Xerces Society / Stephanie McKnight)


How to Submit Data:

iNaturalist app (available for both iOS and Android):

  1. Create an iNaturalist account.
  2. Join the Western Monarch Milkweed Mapper project on iNaturalist.
  3. Add observations to this project using the app by taking a photo of a monarch or milkweed.
  4. Follow the instructions in the app, and fill out all of the data fields (data fields outlined below). The app will allow you to collect location information (latitude, longitude) where you observe a monarch or milkweed.
  5. Submit your observation and researchers at Xerces and in the iNaturalist community will verify your observation!

Monarch SOS app (iPhone only):

Download the free Monarch SOS app from the App Store, and follow the instructions!

Western Monarch Milkweed Mapper website:

  1. Snap a photo of a milkweed plant or any stage of a monarch butterfly (eggs, larvae, pupae, or adults).
  2. Record location information (latitude, longitude).
  3. Record relevant information for milkweed: number of milkweed plants, whether the plants are flowering or fruiting, a, mating or egg laying and if the plants have any monarch eggs, larvae, or pupae on them. Identify milkweeds using the milkweed key, which profiles over 40 milkweed species found in the West.
  4. Record relevant monarch information: behavior such as nectaring, mating, egg laying as well as the total number of monarchs observed. Use resources on the website to properly identify monarch butterflies and each of the life stages (egg, larva, pupa, adult).
  5. Submit the data via the Western Monarch Milkweed Mapper website.


Further Reading

Western Monarch Call to Action.

Read our blog post announcing the record low monarch numbers, measured in winter 2018-2019.

Learn more about the Xerces Society’s monarch conservation work.


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