This summer certainly has been an unusual one, even by the extremes for which North Dakota weather is known.
Unseasonably cool temperatures have been the rule, leaving air conditioners silent and making people choose between long and short sleeves or whether or not to grab a light jacket in the morning.
Cool-weather-loving flowers are doing well, but vegetable gardens and agriculture crops are running behind schedule. Some may not have enough growing season left to reach maturity. While plant growth is obvious and very visible, it is what is missing and often overlooked that may have a bigger tale to tell.
Bye Bye Butterflies
According to Minot State University professor Ron Royer, 2009 will go down as having a dramatic effect on one of nature's most delicate participants - butterflies. Butterfly populations have been on the downslide for several years due to declining habitat and a general indifference to their plight, but this summer has seen one of the biggest changes on record in North Dakota.
"It's a crummy year. Many species are absent or very, very low. It's too cold and the seasons have really shifted around. Things are out of phase," said Royer. "Some species are here, some are not. It's a real mess."
Royer stays in contact with lepidopterists throughout the Northwest region of the United States, comparing notes on observations of various species. Others also report a dramatic drop in butterfly populations.
"The changes this year are rather startling," said Royer. "I'm hearing that all across the Upper Midwest, I'd say the Northern Plains and Minnesota and Iowa. Everybody I've talked to say the numbers are down dramatically."
The change has been so evident this summer that Royer fears some species may have actually become eliminated. The list includes a half dozen butterflies that reside in North Dakota that have long been considered candidates for the endangered species list.
"The Dakota skipper is one and the powersheik skipperling another. It might be too late already," said Royer. "Some of these I expect I'll never see again in North Dakota. Once butterflies are gone, they're gone forever."
If this summer's cool weather decided the ultimate fate of any species of butterflies remains to be documented, but it undoubtedly is a historic event. The month of July was the eighth-coolest July in 105 years of record keeping, averaging 4.4 degrees below normal. An eight-month trend of below normal temperatures is continuing into August. To date, August temperatures for Minot are running an astounding 8.6 degrees below normal. According to the Old Farmer's Almanac, we can expect more of the same through the end of the month.
Sometimes events in nature are timed so that one species can benefit another. Certain plants must be available when butterflies need them. Some insects need to interact with other insects in order to survive. This year's cooler than normal temperatures have altered the growth timetable of many plants and the hatching cycle of many insects. In short, some things usually unseen are way off schedule.
"A lot of this may relate to things simply happening out of phase, plants that are not available when the butterflies need them," reasoned Royer. "However, if you peruse the data, you'd find other times with local dips but I think things are coming together to produce something more dynamic than what I've ever seen in my lifetime."
Ken Cabarle, Minot, a Ph. D student at the University of North Dakota who is working on an amphibian growth project at Minot State University, agrees that this summer is most unusual. It is his observation that the small insects which comprise the basic diet of North Dakota amphibians were delayed so long that it affected growth rates of toads, frogs and salamanders.
"The bugs, on land and in the water, showed up about two weeks later than usual because it has been so cool," said Cabarle. "The size of many of our amphibians is smaller because of that. I certainly haven't seen as many salamanders. We thought we'd see a bumper crop of toads but we haven't seen that. Too cold, I think."
According to Cabarle, the leopard frog is a species enjoying the cool weather.
"That's kind of an interesting deal," said Cabarle. "We've seen a lot of those and there has been a push to place them on the endangered species list."
Nature's food chain begins with insects. A major change in insect populations necessarily leads to changes farther up the food chain. Because so few studies are done and so little observation made of insects in general, a changing insect population is often not realized until it effects the birds and animals that are dependent upon them.
"It's those little species that are the first indicators of change. It's the proverbial canary in the coal mine thing," said Gary Erickson, manager, J. Clark Salyer National Wildlife Refuge.
Jeremy Peterson, agronomist at Minot's North Central Research Extension Center, monitors several species of insects that fall into the "pest" category - those posing a threat to healthy crops. Those bugs, including a variety of tiny aphids, remain abundant but behind schedule.
"Pretty much all the bugs we put traps out for have been a little bit later in their emergence but there's really not a dip in numbers," said Peterson.
Peterson also noted the effect of the cool weather on North Dakota crops, saying that those crops tolerant of cool temperatures and doing well but crops that rely more on heat, such as corn and sunflowers, need several more days of warm weather for proper growth. It's another change from the norm due to a continuing dip in temperatures.
Planting that was delayed due to a cool spring also means that those crops will mature later than normal, if the weather cooperates. There is a bit of a Catch-22 however. According to Jan Knodel, entomologist at North Dakota State University, late planted crops may fall right into the mouths of hungry insects.
"Several of our aphids do better on late seeded crops," said Knodel. "In most years those crops would be harvested before the aphids become a major problem."
Once again, timing is everything.
When asked about recent observations showing a possible decline in nesting success of upland game birds, Knodel offered a plausible explanation.
"Probably what happened is that the grasshoppers, a major food source for upland game birds like pheasants and grouse, didn't coincide with the hatch quite as good as possible," said Knodel. "All our insects are temperature sensitive and all our insects are late this year, at least two weeks behind schedule."