Shared Goals ///
Greg Mitchell, a research scientist in Environment and
Climate Change Canada’s wildlife research division in Ottawa, echoes these views.
“Citizen science plays a very important role in instilling a sense of stewardship and ownership for the natural world. But it’s also a really awesome way to bring researchers together with the public to work towards a shared conservation goal. To me, it’s like the meeting point.”
Mitchell and Ries have something else in common — both published important butterfly population studies in 2019 that showcased different types of large-scale citizen science data sets and demonstrated their value for analysis.
Mitchell’s paper used 15 years of butterfly count data sourced from the Ontario Butterfly Atlas (2003–2017) and ebutterfly (2012–2017), a database of butterfly observations similar to ebird, to determine what factors in the annual life cycle of the North American monarch butterfly determined the size of the annual Canadian breeding population — essentially, “what’s controlling how many monarchs we see in Canada?” says Mitchell. (continued)
The answer, it turns out, is weather conditions in the southern U.S. and their impact on milkweed growth in that area during the North American monarch’s spring migration.
To determine this, Mitchell and his collaborators, Tara Crewe, a senior scientist with Birds Canada, and Maxim Larrivée, director of the Montreal Insectarium and co-creator of ebutterfly, used the observation data to estimate monarch populations and, for comparison, populations of other species of migratory and non-migratory butterflies from the data sets. Next, they factored in weather conditions and available measurements of overwintering monarch populations in Mexico, and then ran correlations until the spring weather influence was isolated.
Two critical attributes in the ebutterfly data that enabled Mitchell and colleagues to calculate accurate population estimates were the lengths of the lists that observers submit and, as important, the time they spent watching butterflies to compile them. “Let’s say someone lists 15 butterflies in a day,” Mitchell explains. “What that number means changes depending how much effort was put in.”
ebird follows a similar protocol, but inaturalist does not. “There’s still value in observations when there isn’t an effort factor,” says Mitchell, but it needs to be used in different ways.
There’s also no doubt in his mind that ebutterfly and the Ontario atlas made their particular study possible. “Given the geographic range that we’re talking about, I don’t think there is any other way to monitor monarchs or milkweed in the U.S. and Canada without engaging citizen and community scientists,” he says.
Ries’s study, meanwhile, fits into the growing library of “insect apocalypse literature.” Specifically, it is one of the first works to look at drastic insect population declines outside of Europe using data gathered through long-term, systematic monitoring.
Written with lead author Tyson Wepprich, a biologist at Oregon State University, and three others, it estimated the rate of change in abundance and population trends for 81 species of butterflies in Ohio. To do this, the authors analyzed data gathered by volunteers organized and trained by the Ohio Lepidopterists in weekly butterfly surveys over 21 years (1995–2016) at 104 sites across the state. Their overall finding: “total abundance is declining at 2% per year, resulting in a cumulative 33% reduction in butterfly abundance” in the two-decade study period.
From a citizen science perspective, the survey stands out for its scale and scope and the systematic nature of the data collection. In the period studied, volunteers did an impressive 24,405 butterfly surveys following a structured protocol known as “Pollard walks.” Developed in the U.K. in the 1970s by scientist Ernie Pollard, the technique requires volunteers to do weekly walks along the same transect (a straight line through an area) at the same pace in fair weather counting every species seen within a five-metre zone around the observer.
Ries calls Pollard a “visionary” who grappled with the fact that monitoring programs for birds that existed at the time couldn’t take into account butterflies’ shorter lifespans. “Birds are vertebrates and they’re long-lived, so a lot of time we’re interested in what’s going on in the breeding season and then maybe the winter season,” she explains. “You can do one set of surveys to get a snapshot. Whereas with butterflies, if you go out and see all these butterflies, and then you go out two weeks later, you’ll be seeing all different butterflies. So, if you want to get a sense of what is going on, you have to have more repeated, structured surveys.”
Both Ries and Pocock acknowledge that Pollard walks are on the high end in terms of required commitment and level of expertise from the volunteers. “Why do people do that?” asks Pocock, rhetorically. “I think it’s something about connection to place, possibly a sense of duty that they want to help nature.”
At the other extreme is someone who merely takes note of nature around them and uploads photos to inaturalist if they see something interesting. “I consider that citizen science as well,” says Ries.