Proposal to install a weather station in the Pacific Grove Monarch Sanctuary

Note:  The presentation slides referred to in the following article can be viewed here: BNRC Presentation 12.17.19.compressed.


Proposal to Install a Weather Station at the Pacific Grove Monarch Sanctuary Presented to the Pacific Grove Beautification and Natural Resources Commission December 17, 2019
Dominick Sinicropi, Ph.D.


It is my contention that more than a decade of habitat loss at the Pacific Grove Monarch Sanctuary has led to the current critical decline in numbers of Monarchs overwintering at the Sanctuary for the entire season as compared with other coastal California overwintering sites. Given the magnitude of the loss I do not think it is productive to blame individual stakeholders for decisions that have been made in the past. What is clear from the data I review below is that the habitat at the Monarch Sanctuary is in steep decline. The actions taken during the last decade have not been effective at rehabilitating the habitat at the Monarch Sanctuary. However, as discussed further below, I believe the current trend can be reversed with science-based planning and management. We need to pursue a different approach to management of the site to turn the situation around. At this critical time, it is more important than ever to communicate proposals among all stakeholders and reach consensus on a long-term plan to restore and responsibly manage the Sanctuary habitat in the future.

There are many factors that have contributed to the 99% decline in numbers of Western monarchs overwintering in Pacific Grove since the 1990s and most of those factors have occurred outside Pacific Grove along their inland migration route. There is little that we can do locally to influence the causative factors outside of Pacific Grove and that is not the focus of this proposal. Rather, the focus of this proposal is to highlight the needed restoration of the monarch habitat for those few butterflies that make it here to insure they are able to survive the winter months and produce new offspring in Spring. Rehabilitation of the Western monarch population requires restoration of BOTH their overwintering habitat along the California coast AND restoration along their Spring and Summer migratory routes. Monarch biologists all agree that the health of the monarch overwintering habitat along coastal California is essential for survival of the species.

The second slide in my presentation shows the dismal counts of butterflies at the Pacific Grove Monarch Sanctuary compared with other overwintering sites along the California coast during the 2018-2019 and 2019-2020 seasons. Only 815 monarchs were counted in the 2018 “Thanksgiving Count” at the Monarch Sanctuary and even fewer (642) were counted in the recent 2019 count. However, we can see that the year-over-year counts at other overwintering sites to the North and South of Pacific Grove were considerably improved in 2019 as compared with 2018. These data show that the number of overwintering monarchs in the PG Monarch Sanctuary continues to decline in 2019 while the numbers of monarchs overwintering at sites to our North and South has improved, and in some cases has more than doubled. These data should be a wake-up call for those responsible for local governance of the Monarch Sanctuary in Pacific Grove. The habitat in the Monarch Sanctuary is becoming less protective for overwintering monarchs and they are choosing to leave in favor of sites to our North and South. Pacific Grove is in danger of losing it’s status as “Butterfly Town USA”.

Even more alarming is the decline in numbers of monarchs within the Sanctuary after a series of storms that affected the area after November 26. As documented in the Monterey County Weekly article referenced in the third slide of my presentation, the number of monarchs in the Sanctuary decreased to fewer than 200 after those storms. As I will describe in more detail below, this decrease in monarch numbers following a series of storms signals an alarming transition that is underway at the Pacific Grove Monarch Sanctuary.

Given the alarming data, why is it important to consider installing a weather station in the Sanctuary now? In slide 4 of my presentation I summarize the rationale for installing a weather station in the Monarch Sanctuary. First, accurate weather data recorded in the Sanctuary is essential for science-based decision-making on restoration and planning for maintenance of the Sanctuary. Currently, the annual report commissioned by the City from Creekside Science only contains weather data reported from the Monterey Airport. This is an egregious flaw in the reports commissioned by the City from Creekside Science. Apart from the fact that weather conditions at the airport frequently do not reflect weather conditions at the Monarch Sanctuary, it is completely indefensible that weather data from the airport should be taken as representative of the microclimate at the Monarch Sanctuary.

Accurate weather data from within the Monarch Sanctuary are needed for several reasons. First and foremost, it is important to document the wind, temperature, rainfall, and solar radiation data within the Sanctuary. This is important to document because it provides the basis for decision- making regarding the location of trees to plant to provide a windbreak while maintaining sufficient solar radiation to support an overwintering population of monarchs. Obtaining local weather data is critical for understanding the relation between severe weather events and the effect of those events on local monarch populations. Acquiring local weather data during the overwintering period will provide data essential for developing a plan for habitat restoration.

Understanding the importance of weather data for proper management of the Monarch Sanctuary is summarized in my fifth slide. In fact, during the 1990’s Dr. Kingston Leong from Cal Poly in San Luis Obispo installed a weather station in the Sanctuary and used the data to make recommendations for proper management of the Sanctuary. For reasons unknown to me Dr. Leong’s connection to the Monarch Sanctuary was lost after 2000 but he continued to work at monarch overwintering sites to the North and South of Pacific Grove. As recently as 2016 Dr. Leong published the paper referenced in slide 5 which details his method for using local weather data to develop plans for rehabilitation of monarch overwintering sites that have suffered habitat declines. In some of the locations he studied the weather data used to develop restoration plans led to improvements in the number of overwintering monarchs. I’ve excerpted the following sentence from Dr. Leong’s paper which I believe is particularly noteworthy with respect to the current decline of the habitat in the Pacific Grove Monarch Sanctuary: “Eventually, if not managed, climax grove conditions will transform into a transitional state due to normal grove maturation or tree losses due to winter storms, diseases such as pine pitch canker, or indiscriminate tree thinning by property managers.” What Dr. Leong defines as a “climax grove” is one in which monarchs arrive in October and overwinter at the site until they leave to mate in February – April. In contrast, a “transitional” grove is one where monarchs arrive in October but leave before the end of the overwintering period due to unfavorable conditions during weather events. It is clear from the monarch count data obtained this year and last year that Dr. Leong’s prediction is currently underway at the Monarch Sanctuary, that is, the Sanctuary is transitioning from a climax grove into a transitional state that does not support monarchs throughout the overwintering period.

The sixth and seventh slides summarize details of my proposal to install a weather station at the Sanctuary. I believe the content of those slides are reasonably self-explanatory and all aspects of the proposal are open for discussion and compromise. In particular, I am proposing to install the weather station in partnership with the Department of Public Works to benefit from their expertise and authority in management of the Sanctuary. Also, I believe it is essential that the data produced by the weather station be made publicly available on the internet for all interested parties to evaluate and support their recommendations for proper maintenance of the Sanctuary.

The eighth slide of my presentation shows an example of the type of data that the weather station will produce. Weather parameters such as “Outdoor Temperature”, “Wind Speed”, “Wind Gust”, “Wind Direction”, “Hourly Rain”, etc., are shown in the first row of the spreadsheet. Subsequent rows are data collected by the weather station every five minutes, 24 hours per day, 7 days per week, 364 days per year. Weather in this format is particularly useful for scientist wanting to correlate with other information such as monarch count data, weather events, and location of trees. However, other users might be interested in a more graphical user interface examples of which are shown in slides nine and ten. In slide number nine is shown a screenshot from one of three possible websites where the data obtained in the past 5 minutes can be displayed in graphical format. In slide number ten an example of temperature and wind speed data has been graphed over a 24 hour period. In the graphic format weather data can be displayed up to 30 days prior to the current date or for longer periods if the spreadsheet data are imported into a separate data graphics application.

The 11th slide of my presentation is a summary of my proposal to install a weather station at the Pacific Grove Monarch Sanctuary. I believe the content of the slide is self-explanatory but the conditions of my proposal are open for discussion. Turning the situation around at the Monarch Sanctuary will require a long-term plan and implementation of the plan for a minimum of 10 years before the effectiveness of the new plan can be assessed. Installation of a weather station in the Sanctuary is a small initial step toward this long-term goal. However, I believe it is a step long overdue and a step in the right direction.

1 thought on “Proposal to install a weather station in the Pacific Grove Monarch Sanctuary”

  1. Update on the weather station:

    I’m happy to announce that the weather station is installed and operating at the Monarch Sanctuary! I want to thank Caleb for his support in getting approval to install the weather station. The design and choice of components for the weather station was a collaborative effort with Caleb and I appreciate his helpful suggestions.

    The data is updated every 5 minutes over the internet and can be viewed at the links provided below. If clicking on the links doesn’t work, copy the entire link and paste it into the address bar of your browser. By default the Ambient Weather link opens up to a page with graphs of the data recorded over the last 24 hours. However, you can switch to a table of the recorded data by clicking on the icon that looks like three horizontal lines. When you click on that icon it will first show the Average, High, and Low data in several categories. However, if you click on the + icon at the bottom of the table it will expand to show the data recorded every 5 minutes for the last 24 hours. I am working on a way to archive this data 24/7/365 to a database.

    The data is also being uploaded to Weather Underground which you can access at the link below. However, there is currently a glitch where the location of the weather station and it’s name are not correct. I am working in the next couple of days to correct these errors.

    Meanwhile, when you are curious about the weather conditions in the Sanctuary just click on the links below to see what is going on there!


    Ambient Weather

    Weather Underground (Note: The name and location of the weather station are not correct and will be updated in a few days)

Comments are closed.