A few months ago, on a trail run in the Bear River range in Northern Utah, I became engulfed in a cloud of butterflies beyond anything I had experienced before. Milbert’s totiseshells and Swallowtails were the primary species. This is the year of the butterfly. I have seen many eruptive populations both in Northern and Southern Utah. Especially in the tortoiseshell family in the North and bumper crops of Field Crescents at Cedar Breaks National Monument in the south.
This has given me pause to reflect on how climate change may be influencing their populations. As I described in an earlier Wild About Utah reading, over half of Utah bird species are showing considerable stress from a changing climate. Might the same be occurring for the Lepidopterans, or butterflies?
Many studies have shown that that butterflies are among the species that have responded the most to climate change, usually in the form of northward or elevation range shifts. There are many documented instances of disruption of essential interactions of butterflies with their food plants. Recently, a number of researchers have warned, that the common biological effect of shifting towards earlier time to reproduction can have multiple and cascading effects. Species lacking adaptability may have reduced fitness, increased mortality and disrupt a whole food web which had evolved to thrive when there was a synchronous timing of resources that can no more be found. Climate change can also effect flight times of butterflies. The warmer temperatures will result in more generations of multiple brooded species. But how this will effect egg laying periods and other life traits that are determined by photoperiodism is unknown.
With a warming climate, butterflies at the highest elevation site are appearing with increasing frequency. Those that normally breed at 7000 feet now breed at 9000 feet. This upslope movement can cause a time lag problem because plants move more slowly than butterflies. If butterflies don’t have the plant resources they need, they cannot breed at these higher elevations. This may explain the low numbers of butterflies I’ve noted in my outings at Tony Grove lake in recent years.
In order for conservation plans to be developed, there is a pressing need for a better understanding of how climate effects Lepidopterans and their essential interactions. There is much we still don’t know. With more information, on these intricacies, we can better design more effective plans.
A month ago, I found myself in England assisting a team of Darby University faculty and students for pollinator research which included butterflies and moths. European scientists are well ahead of the US in the understanding of patterns of butterfly response to climate change. We must step up to the challenge if we and future generations are to continue enjoying butterflies for years to come.
Later this month I will be leading a butterfly field trip to Tony Grove lake followed by joining a University of Washington PhD student on Mount Rainier to study butterfly populations. …my small contribution towards maintaining healthy numbers of these marvelous creatures that brighten our day and make significant contributions towards maintaining ecosystem stability.
This is Jack Greene writing and reading for Wild About Utah.
Pictures: Courtesy & Copyright Shalayne Smith-Needham, Utah Public Radio
Text: Jack Greene, Bridgerland Audubon Society
Denali’s Butterflies – Denali National Park & Preserve, https://www.nps.gov/dena/learn/nature/denalibutterflies.htm
Crescent (Phyciodes sp.) Butterflies, Lee Metcalf National Wildlife Refuge, Montana, US FWS, https://www.fws.gov/nwrs/threecolumn.aspx?id=2147574863
All About Butterflies, Enchanted Learning, http://www.zoomwhales.com/subjects/butterfly/allabout/
Andrea Liberatore, Monarch Butterflies, Wild About Utah, 13 Sept 2012, http://wildaboututah.org/monarch-butterflies/
Jack Greene, Butterflies, Wild About Utah, 4 July 2016, http://wildaboututah.org/butterflies/
Andrea Liberatore, Insect Mimicry and Camouflage, Wild About Utah, 31 July 2014, http://wildaboututah.org/insect-mimicry/
Bugguide, Department of Entomology, Iowa State University,
Species Phyciodes pulchella – Field Crescent, http://bugguide.net/node/view/24562
Species Aglais milberti – Milbert’s Tortoiseshell – Hodges#4433, http://bugguide.net/node/view/30387
Family Papilionidae – Swallowtails, Parnassians, http://bugguide.net/index.php?q=search&keys=swallowtail