Butterflies: tell-tale beauties
August 17, 2007
The Donner Summit region is a fertile ground for butterflies because of a dynamic tension present in the area.
Dr. Arthur Shapiro, a professor at UC Davis, has been studying the lepidopteran order across central California, including Donner and Castle Peaks, for more than 34 years. He described the state of tension existent in the area as a dynamic between the east and west slopes.
Donner Pass is also a fairly low pass, allowing the different species that live on the east and west slopes to intermingle.
“This provides access for species from both the east and west slopes and provides a rather gradual transition in the vegetation,” Shapiro said.
The dynamic between rising and falling numbers of species can be accurate indicators of the health of the planet as well as global change. Studying butterflies in the Donner region has proven to be extremely rich in information, Shapiro said, and recent behavior of butterflies have scientists pointing to rapid changes in the earth’s climate.
“Because butterflies can fly, they can respond to short- and long-term changes in climate in ways undetectable to us,” Shapiro said. “With a pattern of warming, we would expect species to shift poleward . . . and they are. Our database provides detailed documentation of these trends.”
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Although butterflies can migrate quickly to adapt to the changing climate, their movement ultimately depends on their host-plants. If the species’ host-plant is not there, they cannot breed. The larva of all butterflies in the Sierra are phytophagus, meaning they feed on plants.
Moreover, the wealth of data available in the Truckee area can be credited to the amount of disturbance, a valuable factor for butterfly habitats. A disturbance can refer to any sort of interference in the natural habitat including forest fires or, in the case of Donner, the railroad tracks.
The railroad that passes through Truckee was built in the 1860s and created what is called successional vegetation, which butterflies thrive on. Successional vegetation is when an occurrence forces the vegetation in the area to start anew. Each year the plants will grow larger and more mature until the area reaches what is called the climax, meaning it has reached its full potential. The railroad disallows the vegetation to grow into this state of maturity.
“The railroad carter in particular has created an excellent butterfly environment,” Shapiro said. “Most of our butterflies occur in forested or open sites, either meadows or rocky areas or sites where the vegetation is recovering from a disturbance. The railroad carter created a permanent disturbance.”
Forest fires also provide excellent environments for butterfly fauna.
“The recent burn area at Tahoe will be a ‘climax’ Jeffrey Pine forest in 150 to 200 years, but on the way will pass through a number of ‘stages’ dominated by different species”that’s successional vegetation,” Shapiro explained. “Historically, fire in the Sierra has been a friend to butterflies by setting the successional clock back to more open vegetation types.”
Butterflies are not commonly found in closed-canopy forests because they are heliothermic. The winged beauties get their energy from sunlight, therefore cannot survive in shaded forests. They would not be able to accumulate enough energy to fly.
In studying the area, Shapiro said he did not rely on information obtained by Charles McGlashan, a Truckee entomologist in the early 20th century.
“Unfortunately, McGlashan did not keep good detailed records of what he got where. One of the problems has been trying to decode his information and trying to figure out what he did get where so we can assess change in the fauna in the last century,” Shapiro said.
A more accurate account of the butterflies at the beginning of the 20th century can be found in a paper published by E.J. Newcomer in 1910. The paper is called Butterflies of the Lake Tahoe Region and is described by Shapiro as being extremely meticulous, detailed and accurate.
“We can do comparisons for the Tahoe basin then and now,” Shapiro said. “That’s the best baseline we’ve got.”
With a detailed baseline, information collected now and in the future can be compared and changes in the environment recorded. As the environment changes, the creatures living in that environment transition as well. It is important for scientists to study these transitions in order to understand the changes occurring to the planet as a whole.
An entire chapter of SNEP, the Sierra Nevada Ecosystem Project, which was conducted in order to study the status of the Sierra Nevada, is devoted to butterflies. Shapiro, author of the chapter, describes butterflies as being “relatively easy to study” and “large enough to be marked individually (and are identifiable as individuals without recapture).”
In the project, Shapiro also details the lack of butterfly fauna that is endemic, or restricted to a particular region, compared to other montane regions in the western United States. Endemism is important for understanding how fauna evolves.
As of 2007, Shapiro had identified three species of Butterflies endemic to the Sierra Nevada. In order to determine which species were endemic, Shapiro had to find a way to figure out which species had lived in the Sierra well into the past.
Entomologists do not rely on butterfly fossils because as Shapiro says, finding them is “about as likely as picking up Marilyn Monroe’s underwear at a neighborhood garage sale.”
Instead, scientists focus on the fossils of plants. When they find a plant that co-exists with a particular butterfly in the present, it can be assumed that the butterfly-plant relationship has remained stable. By examining the fossils from a certain era, they can determine which butterflies existed as well.
“In many butterfly groups,” Shapiro explains, “host associations seem very stable geographically, that is, over most or all of the geographic range of the butterfly, and they are often stable among related species . . .this is usually a reasonable assumption.”
As populations of butterflies live and mate in the Sierra, they provide an accurate image of the changing climate. And, good news for butterfly aficionados, recreational collecting of the insect, when done in moderation has not been identified as a problem.
Charles Fayette McGlashan was born in Jamesville, Wisconsin in 1847 and moved with his family to California in 1849. He attended Sotoyone Institute in Healdsburg, Calif. from 1861 to 1865 and Williston Seminary in Mass. from 1868 to 1870, after which he moved to Truckee in 1872.
McGlashan became the principal of the public schools in Truckee until 1874 when he resigned to go to Utah to be a corrsepondent for the Sacramento Record. In 1875 he began practicing law and became editor and owner of the Truckee Republican, which later became the Sierra Sun.
As editor of the Truckee Republican, McGlashan published several articles on the Donner Party. The articles led to the publishing of McGlashan’s book History of the Donner Party, A Tragedy of the Sierra in 1879.
The Truckee man also dabbled in astronomy, real estate and inventing as well as the collecting of Truckee area history and lore. Besides these endeavors, McGlashan was an active entomologist, collecting specimens of butterflies in the area.
Although his records are among the first ever recorded for the area, they lack detailed accounts of the locations he collected his butterflies.
Solidifying his role as a prominent Truckee figure of history, McGlashan also actively devoted himself to the financing and construction of Donner Summit Memorials.
McGlashan died in Truckee in 1931.