Monarch Watch Monarch Calendar Project

2024 project page updated 26 March 2024.

Some participants have asked if we will be accepting submissions as before, without using the mobile app, and the short answer is yes. We are working on the details and will post them here soon. In the meantime, please record your observations in whatever way is convenient for you and be sure to check back here for updates. Thank you!

This year we are modifying the calendar project to allow for as many observations as possible because of the extremely low monarch population size (see the recent "Monarch Population Status" post to the Monarch Watch Blog). Records of not seeing monarchs are extremely important so we can understand what is happening with the population this year, so please don't get discouraged if you are mainly reporting zero values.

One of the most significant changes from previous years is we are no longer limiting observations to a particular time period based on your location (latitude).

Monarch Watch is seeking the immediate assistance of hundreds of monarch enthusiasts (community scientists) in collecting observations of adult monarchs in their area during 2024. This project is an attempt to assemble quantitative data on monarch numbers during the breeding season. The data from these observations will be used to inform the status of the monarch population this year following an extremely low population size on the overwintering grounds.


Why do we need a "monarch calendar" and your help recording monarch numbers?

The decline in monarch numbers over the last 20 years has inspired numerous attempts to define critical factors that explain the inter-annual variation in monarch numbers. The data sets used for these analyses have had a variety of limitations which have either been ignored or underappreciated by the authors of several publications. The truth is that much of the data that is available is too general and does not adequately represent important aspects of the biology that underlies the development of the population each reproductive season.

There are numerous gaps in our knowledge and some of these gaps can be addressed if we can convince a large number of monarch enthusiasts (community scientists) to record the number of monarchs they see each day.

We need a better estimate of the number of monarchs that arrive in Texas and Oklahoma from Mexico each year. This starting number has not been captured effectively. We also need to capture more information about monarch activity throughout the breeding season leading up to the fall migration.

To provide meaningful data, we need to recruit hundreds of volunteers to record what they see.


Here is what we need you, as community scientists, to do:

1. Download the Monarch Watch Mobile App

Download the Monarch Watch mobile app today to participate in Monarch Watch community science projects and submit your monarch tagging, recovery and calendar data! Now available for iOS and Android devices.

2. Complete your profile

You will be prompted to enter your name, address and email address then confirm you have read and understand the privacy policy and agree to the terms and conditions (standard mobile app).

3. Select "Monarch Calendar Project" to start recording data

Record every adult monarch seen in your location for specific periods depending on your latitude. To keep these records all one has to do is to enter the number of adult monarchs seen each day in which seeing a monarch was a possibility. If you were outdoors and saw none, record a zero (0). On the other hand, if there was no opportunity to make any observation due to work or vacation, etc., leave that date record blank. There will often be days when monarchs can't be active due to weather conditions (e.g., low temperatures, extreme overcast, heavy rainfall). These intervals, if long enough, can also impact population growth. A "W" (for weather) should be entered for each of these days. Be sure to tap the "Submit" icon for each day's record and you can review your submitted data at any time by tapping on the "My log" icon.

Please download the Monarch Watch App and start logging your observations today! Thank you in advance for your assistance - if you have any questions or comments about this project, please contact us at



We've tried to summarize questions we've received about our Monarch Calendar Project and, through the answers, clarify how we'd like you to record the data. We made some modifications for this year (2024) to reflect the goal of collecting additional data due to the extremely low size of the overwintering population.

We need a better way of predicting the fall migration and the size of the overwintering population. This project is an attempt to capture the seasonal dynamics of the monarch population that will help us understand how the population develops through the breeding season.

Thanks for your willingness to participate in this project. We appreciate your help. As you can see, from the scope of the project, the only way to obtain these data is through the cooperation and commitment of a large number of citizen scientists such as yourself. Again, we appreciate your help and we are looking forward to receiving your data.

Questions and Answers

1. When should I start my calendar?

The idea is to keep the record keeping as simple and as accurate as possible. Because of the low size of the overwintering population this year, we recommend starting when sightings are reasonable given your latitude and based on timing for previous years when there were more monarchs.

2. How do I make counts? Suppose I see an adult monarch six times in my garden during a day do I count that as six butterflies or one?

The rule here has to be to use common sense and be conservative. Egg-laying females in the morning and patrolling males in the afternoon will often return to the same patch over and over on a given day. If during the sightings, the observed butterfly appears to be the same color, size and condition, count it as a single butterfly. Females are darker than males and male/female behavior is different. Careful observations should help you distinguish one butterfly from another. However, if you are uncertain, be conservative and record the lower number.

3. What if I am in an area in the northern part of the range where monarchs are seldom seen before 20 June?

Actually, we want to confirm that monarchs aren't seen above certain latitudes until after the 20th of June. Please submit data so we can evaluate the timing of monarchs for these areas.

4. What if I work during the week and can't make observations? Or, do I have to observe for a certain length of time on a given day to record a number seen or a zero?

We expect the opportunity to observe will vary greatly for each observer over the calendar period and that some observers will, by virtue of opportunity, activity or lifestyle, see more monarchs than others. That's fine. We want to capture relative numbers over large areas and long time periods for multiple years. Don't worry if you don't see monarchs or don't spend a lot of time looking for them. Just record what you see and, if you think there was a good opportunity to have seen a monarch and didn't, just record that day as a zero. If you had no opportunity to observe, then you don’t submit anything for that day. We expect more no submission days and 0s with some Ws (for "weather" - see #7 below) than actual numbers sighted.

5. If I raise and release monarchs, do I count those?

The short answer is no. We are trying to record the dynamics of the wild population.

6. What about species that are easily confused with monarchs?

Yes, there are species that are sometimes confused with monarchs, most commonly the viceroy and the queen. In flight, the viceroy flies closer to the ground than monarchs and frequently lands on the ground. It is also less likely to visit flowers. However, when on flowers, viceroys and queens can be easily mistaken for monarchs. Monarchs are larger than both of these species. All we can tell you here is to learn your butterflies, observe closely and do your best. If you realize after submitting your data that you were identifying another species as a monarch, just let us know and we can make corrections to the data as needed.

7. When should I record a W for weather? What weather conditions limit monarchs?

Low temperatures (mid 60s and lower), extremely high temperatures (95 and higher), extreme overcast, rain, and high winds can completely stop monarch activity. When that happens, please record a W for weather. The Ws are important. There is no reproduction during a W - no mating, no egg laying and, if the temperatures are low, larval development slows down as well. Monarchs can get off to a good start and then be slammed by weather that shuts down reproduction. We need to capture that. Five consecutive days of low temperatures and rain can have a strong negative impact on a population that can easily be missed if projections are based on mean monthly temperatures. We aren't really concerned about the weather before monarchs arrive. If necessary, we can capture weather data from "Weather Underground" for the periods prior to the arrival of monarchs in any region.

8. Why aren't you asking us to record eggs, larvae and migrating monarchs?

The reason is simple; there are other programs that provide data on these aspects of the life history. Please see the following links if you wish to participate in any of these programs.

First eggs - these sightings can be reported via Journey North (

The Monarch Larval Monitoring Project (MLMP) at the University of Minnesota tracks both larvae and eggs (

Migratory monarchs are tracked by Journey North through sightings of overnight roosts (

Monarch Watch's tagging program captures data related to the size and dynamics of the migratory population (

All material on this site © Monarch Watch unless otherwise noted. Terms of use.
Monarch Watch (888) TAGGING - or - (785) 864-4441