Why a Census? Every ten years, Saguaro National Park leads a citizen science Saguaro Census to study the long-term health and vitality of the park’s namesake cactus. Although we have studied saguaros at the park for many decades, beginning in 1990 scientists developed a new study to assess the overall conditions of saguaros across the entire park, including both the east and west districts. The saguaro census is meant to be repeated every ten years and coincides with the US Census. Beginning in late 2019 and continuing through late 2020, park scientists, staff, and citizen scientists collected data on tens of thousands of saguaros throughout the park.
The Saguaro Census is on Hiatus! Due to the COVID-19 pandemic, in March 2020 the 2020 Saguaro Census was suspended indefinitely in the interest of safety. The Census was already drawing to a close, but we were very sorry to have to cancel the final scheduled events.
The great news is that between October 2019 and March 2020, Citizen Scientist volunteers had accomplished amazing work. 475 individual volunteers worked an astonishing 670 person-days and over 3,400 hours. These Citizen Scientists finished more than 40 of the 45 plots (plus a number of "historic plots" that date to the 1940s). Together with park interns and youth crews they mapped, measured, and collected other data on more than 20,000 saguaros!
What Have We Learned So Far? It is too soon to know whether the number of saguaros has increased in Saguaro National Park since the estimated 1.9 million in 2010. We do know that some areas had increases in the big cacti, while others saw declines (see the "Results" section below). The most saguaros found on a single study plot (each plot is about 10 acres) was 1,746.
We are still considering options to finish the Census either in the fall with Citizen Scientist events; in the summer with park interns; or a combination of both. Our final decision will be based on changes in the COVID-19 situation. When the Census is complete we will analyze the data, release the results, and celebrate with our volunteers and friends. Stay tuned! If you have questions, please email Don Swann at Don_Swann@nps.gov.
