In July 1993, my wife, Marlene, and I started small by having two “Fourth of July” butterfly counts at Itasca State Park and Deep Portage. Since 1995, we’ve done six summer counts each year in north-central Minnesota.
In 2020, our 28th season, we achieved our 161st 4JC, as they are called for short.
Last year was a season of milestones achieved, while this year presented COVID-19 challenges.
How did we adjust? Mainly, we had teams only composed of related members. Instead of gathering before and after counts, we generally shared results only by mail or phone.
In these annual articles, I always voice my appreciation for the small band of counters who participate. This year, I certainly welcomed the patience and understanding they displayed during these unsettling times.
Unfortunately, I felt we could not safely incorporate any of the newer counters on teams this year. I hope this will be only a one-year hiatus and that they will agree to rejoin us in 2021, if it’s safe to do so.
Present on all six counts
There were 15 species, too numerous to name here, present on all six counts. They represented almost half (47.3 percent) of the season’s 11,296 individuals. What I found most interesting was the wide range in numbers – from 43 to 901 per species.
Top five species
For the second year in a row, I’m commenting on the top five, not the top 15. That’s because these five were so dominant: European skipper, dun skipper, common wood-nymph, northern crescent and monarch, in that order.
This year’s top five had a 63.7 percent share of total individuals. Last year’s top five was even more dominant, with a 71.1 percent share.
However, this year’s top five individuals dropped 3,539 from where those same five stood in 2019. Three-fourths of the decrease was registered by European skippers (-2,593). More on European skippers later.
Needles in haystack
The 14 species we encountered with only three or fewer individuals really kept us on our counting toes. Though they represented about 20 percent of the total species, they contributed less than 0.2 percent (that’s two-tenths of a percent!) to the overall 11,296.
A lone Milbert’s tortoiseshell was one such species.
Here’s a brief overview of our six summer counts.
Nevis began the season with a bang on June 27. European skippers were three of every four individuals (3,430 of the total 4,628). Only eight Euro skips were present in 2019! Non-Euros were down almost a full 600 from 2019.
The Bluestem count in Clay County was held nine days earlier than in 2019. It posted respectable results: 1,339 individuals. Highlights were black swallowtails, summer azures, surprisingly early 10 regal fritillaries and common wood-nymphs.
The Deep Portage count on July 7 had far fewer Euro skips this year – only 317 versus the mind-boggling 5,743 last year. Non-Euros nicely increased to 1,051 from last year’s 630.
Itasca State Park, with one less team in 2020, still recorded 46 species and only 159 fewer individual butterflies than 2019.
Central Polk County fared much better than the 2019 scheduling debacle, as 33 species and 954 individuals were tallied. Drought conditions meant the nectar sources that looked promising lacked nectar.
Bemidji closed the 2020 season on a very sour note. Held July 19, persistent clouds and strong – gale-force, at times – cold winds really put a damper on the day: 10 fewer species and 2,638 fewer individual butterflies.
Northern crescent update
The northern crescent is still the only species present on all 161 counts we’ve had. For many years, it was the most common species. That’s no longer the case, in more recent years. Last year, they ranked No. 2, but slipped to No. 4 this year after a decline of 878 individuals.
After the first count of the year at Nevis, where 389 were present, they steadily declined each subsequent count until only 34 remained for Bemidji.
Northern crescent caterpillars feed on asters. Our road ditches used to be filled with all sorts of wildflowers, including asters. For years now, we’ve witnessed fewer and fewer wildflowers there.
So the streak is definitely in jeopardy.
Euro skip factor
As mentioned earlier, even with a substantial drop of 2,593 individuals from 2019, European skippers repeated as the No. 1 most common butterfly, with 3,788 present this year. The Nevis count commanded 90.5 percent of all Euro skips tallied this year. They have an intense, but brief adult flight season. After dominating Deep Portage in 2019 and Nevis in 2020, it will be interesting to see how they play out in the future.
Purpose of counts
A 15-mile diameter circle is established for each count. On a single day, all living butterflies found in that circle are tallied and reported to the North American Butterfly Association.
Our counts are among 300-some held each year in the U.S., Canada and Mexico. These citizen-gathered data provide valuable snapshots of butterfly population trends in North America.
2020 marks the 46th year the Fourth of July counts have been held.
Monarchs and more
Our counts this year tallied 765 adult monarchs, a modest increase from 2019’s 758. Since I’ve observed so few monarch eggs and caterpillars on separate 11-week monitoring visits, I’m puzzled. Where are the adults coming from?
As I write these words, almost a full month after our summer counts ended, we’ve had a full spectrum of weather events. There has certainly been a mixed bag, with good, bad and indifferent impacts that will dictate how the 2020 butterfly season ends.
To date, I’ve only seen a sprinkling of species and individuals on the wing. I doubt there will be a last-minute flurry by any butterfly species, such as we’ve had in the past. Cabbage white, clouded sulphurs, painted ladies and monarchs come to mind.
I encourage you to savor every butterfly encounter you may still have this fall.