The Friends of the Wilderness Park have partnered with the Monarch Joint Venture to implement the Integrated Monarch Monitoring Protocol (IMMP) in the Claremont Hills Wilderness Park. As stated by the program, “IMMP is a national program to collect milkweed, nectar plant, and monarch use data from a variety of land-use types and regions. This information is vital to shaping our understanding of how monarchs interact with their environment, documenting conservation efforts, and tracking the population and its habitat as they change over time.”

Data collected from this project will provide useful baseline data for any future Monarch and pollinator conservation efforts in the Wilderness Park and will also be an asset for future grant proposals directed toward conservation.

These data are especially important given the decline in Western Monarch populations. Data from California are sorely needed, and the CHWP monitoring site is currently the only one in Los Angeles County, one of only two in Southern California, and one of only five in the entire state.

We are also mapping all the milkweed locations in the Park. This information will be useful for determining the location of possible future monitoring plots and will enable us to determine whether the milkweed populations are expanding or contracting over time.

Read on to learn more about this project and how you can be involved.


Two species of milkweed, the host plants for Monarch butterflies, grow in the Wilderness Park – Narrowleaf Milkweed (Asclepias fascicularis) and Woollypod Milkweed (Asclepias eriocarpa).  So far as we know, all the milkweed in the Park is in Johnson’s Pasture. 

Narrowleaf Milkweed (Asclepias fascicularis) growing in Johnson’s Pasture.
Woollypod Milkweed (Asclepias eriocarpa) growing in Johnson’s Pasture.

We know that these plants are visited by Monarchs and used as hosts for their caterpillars, but we do not know to what extent the CHWP milkweeds support the Western Monarch migration nor the extent to which they support other important pollinators.

A Monarch butterfly (Danaus plexippus) on Narrowleaf Milkweed (Asclepias fascicularis) in Johnson’s Pasture.
A fifth instar Monarch caterpillar on Woollypod Milkweed (Asclepias eriocarpa) together with a Longhorn Milkweed Beetle (Tetraopes basalis) and a Valley Carpenter Bee (Xylocopa sonorina) in Johnson’s Pasture. ©Jon Moore.
A male Crotch’s Bumble Bee (Bombus crotchii) on Narrowleaf Milkweed (Asclepias fascicularis) in Johnson’s Pasture. Crotch’s Bumble Bee is listed as “Endangered” by the International Union for Conservation of Nature.

IMMP Monitoring Activities

We have established a 200m x 50m monitoring plot in Johnson’s Pasture and registered the plot with the Monarch Joint Venture.

Monitoring activities begin when new milkweed growth is apparent (usually April) and continue through October, when monitoring activities end for the year. The IMMP monitoring activities that we’re carrying out are:

ActivityBrief descriptionFrequencyTraining videos
Site Description, Part 1Complete required form with information about land ownership, status, conservation, vegetation, etc.Once at start of monitoring seasonSite Description
Site Description, Part 2Update disturbances, management activities and changes in vegetationEach visitSite Description
Activity 1:
Milkweed and Blooming Plant Survey
Record any milkweed (number of plants and stems) and any other blooming plants within 1-m x 2-m subplots at 5 m intervals along two 200-m transects and one 100-m transect within the plot. Also walk through the whole plot and record any additional blooming plant species not recorded in the subplots.MonthlyHabitat Survey 1: Basics
Habitat Survey 2: Standard Rectangle
Habitat Survey 3: Subplots
Activity 2:
Monarch Egg and Larva Survey
Examine all milkweed plants withing 2m to either side of two 200-m transects and one 100-m transect within the plot for Monarch eggs and larvae, and the number and stage on each plant, up to 100 plants.WeeklyMonarch Egg & Larva Survey
Monarch Identification
Activity 3:
Adult Monarch Survey
Walk the perimeter of the plot, recording all adult butterflies seen within 5 m to either side. Also record whether butterflies are flying, resting, ovipositing, mating, or nectaring (noting the plant species).Bi-weeklyAdult Monarch Survey

Full descriptions of the IMMP protocols and forms for recording data may be found at:

All of the IMMP training videos are available online at:

Volunteer to help monitor Monarchs & Milkweed

We are looking for volunteers to help monitor Monarchs and milkweed! If you’re interested please email us at, and indicate your interest. Please note the following:

  • Because of the ongoing COVID-19 pandemic, we require all volunteers to be fully vaccinated against SARS-CoV-2.
  • All volunteers engaged in monitoring will undergo training and will submit the required waiver for the City of Claremont
  • All volunteers will wear Friends T-shirts or safety vests while working.
  • Because this work will require going off trail, volunteers will be instructed in and required to adhere to appropriate safety precautions for rattlesnakes, including:
    • Wearing boots.
    • Wearing long, sturdy, loose-fitting pants.
    • Not reaching or stepping where one can’t see what’s there.
    • Using a walking stick to touch the ground where one will step next, parting the grass with the stick if needed in order to see the ground.

Mapping milkweed in the Park

To create a map of milkweed locations, we are using the Calflora Observer Pro app on a smart phone or tablet. Using Observer Pro, we record:

  • The GPS location of a milkweed plant or patch of milkweed plants.  For single plants or small groups of plants, we will record a point.  For larger patches we will record a polygon that encloses the patch.
  • The species identification of the milkweed – A. fascicularis or A. eriocarpa.
  • The number of plants represented by the point or patch.
  • We have completed the map for the area of the current monitoring plots, but want to map the additional milkweed locations in the Park.

Here are the mapped milkweed locations as of April 2022:

You can see the latest map of milkweed locations in the Park by clicking here.

Volunteer to map milkweed in the Park

We are looking for volunteers to help monitor Monarchs and milkweed! If you’re interested please email us at, and indicate your interest. We’ll arrange for everything you need to get started.