Researcher Victoria Bennett spent last summer running around, literally chasing butterflies.
“It can be hard, sweaty work especially if it’s on a bloody slope.” said Bennett, who grew up in England and earned her undergrad, masters and doctorate degrees at the University of Leeds, West Yorkshire.
Bennett is a post-doctoratorate researcher at Oregon State University, based in the Department of Forest Ecosystems and Society, with Matthew Betts, a landscape ecologist specializing in hummingbirds, and Winston Smith, a USDA Forest Service wildlife ecologist famous for his work on flying squirrels, as her supervisors.
Her current research is funded through a grant from the National Geographic Waitt Grant Program and a general research fund grant from OSU.
Bennett uses computer simulations to look at how species move across the landscape. Her field work enables her to gather specific data she needs to create virtual butterflies that act like their wild counterparts.
“Data collection can often be limited by scale,” she said. “We can see the small-scale processes very easily like the way a butterfly nectars, where it lays eggs, or how it moves across a field, but tracking how it moves across the landscape is much harder to do.”
That’s where an innovative techniques and modeling simulations can help. This spring, her team will be using new technology — a harmonic radar system — to follow butterflies.
Each butterfly in the study will be outfitted with a transponder no larger than a flake of dust. The same tiny transponders have been used by other researchers to track locust storms and reveal how bumble bees and honey bees go about pollinating over a geographic area.
The plan is to tag about 10 individual butterflies each week and use the harmonic system to follow those individuals more effectively than her team has been able to in the past. Being able to follow individuals for longer will allow Bennett to see what they are doing over the course of a day and hopefully a week or more.
“Without it we tend to be limited to a few hours, as it is never long before the individual we are following ducks behind some vegetation out of sight or has an aerial altercation with one or more individuals,” she said. “Telling one individual in a swirling mass apart from another is tricky. By using a handheld harmonic radar system, we can continue to collect data on an individual which we would have otherwise have lost.”
“Ultimately we’re following individuals and we’re mapping out exactly where they move and exactly how they behave,” she said. “We’re getting the full story.”
To compare butterfly movements and behavior, Bennett hopes to gather data on two or more rare species, including the Taylor’s checkerspot and Oregon Silverspot and four or more common species, including the Common wood nymph, Common ringlet, Western tail blue and Western meadow fritillary.
So far, her team’s field sites have included meadows on the Oregon Coast, Olympic National Park in Washington, and various local green spaces such as Fitton Green Natural Area, Adair Wildlife Area, E.E. Wilson Wildlife Refuge and Marys Peak.
“Butterflies can be very cryptic once they get in the grass,” Bennett said. “And with the rare species especially, walking on their habitat when there is a chance you might crush a butterfly is not a good idea.”
The harmonic tracking system is providing a new way to keep tabs on the butterfly’s location without disturbing its immediate habitat or running the risk or injuring or killing it. The hope is to use the same type of transponders to monitor caterpillars in the future.
When her team returns to tracking butterflies this spring, they will in turn be followed a documentary film maker who hopes to have the project picked up by National Geographic.
It should be a challenge for the filmmaker. When it comes to being captured on film, Bennett absolutely refuses. She wants the public to be aware of her work, but that’s all that is important, she said; not personal recognition.
Bennett started studying anthropogenic (human-caused) disturbance of wildlife, long before she arrived at OSU, primarily with bats and birds. She focused on the effects of “non-consumptive” recreation such as bird watching.
“Do you know that wildlife watching can have a negative impact?” she said. “When wildlife individuals are scared, flee, or freeze in response to your presence, you are ultimately interrupting their natural behavior. For some species this can have fitness and reproductive consequences.”
For example, higher levels of stress can affect overall health and survival rates. Not to mention, all that human attention can attact predators, such as hawks, she said.
Bennett’s research gets at several key dilemmas: How do we protect species while maintaining recreational access to wilderness areas? How do we minimize the effects of development on wildlife?
“All too often we just don’t know how effective our mitigation is,” she said. “When it comes to species of concern, managers are under pressure to implement recovery management immediately. Without specific knowledge of a species’ needs and sensitivity to recreational activities there is a chance that something as basic as the placement of a foot path can have consequences.
“Having been in the position where I had to make decisions on appropriate management, I found this uncertainty frustrating,” she said. “I returned to academia especially to develop practical techniques that would relieve such management black-spots.”
Her work in the United Kingdom with species of concern, primarily bats, led her to Purdue University to work with the Karner Blue Butterfly and the Indiana bat — both endangered species.
For the former, she studied how walkers on a pathway disturbed individual butterflies from laying eggs. Females are choosy about selecting a location and laying a single egg can take up to 15 minutes or more.
“If someone walks by while a female is attempting to lay an egg, she will flush (fly away). That female will then start the whole process over again, finding a suitable plant.”
If disturbed enough, the outcome will be fewer eggs layed in her lifetime. “We also found in our simulations that females Karner blues will lay eggs farther away from the path,” she said.
“When many butterfly species are limited by host plant availability, it’s actually got the potential to be very detrimental to the population,” she said.
Why did the butterfly cross the road?
The Oregon silverspot, a federally threatened species, first sparked Bennett’s research interest in the Pacific Northwest. It is found on sites in Oregon that are bisected by Highway 101. The butterflies therefore cross the coastal highway to move within their site.
“It’s not just the direct effects of being hit by a vehicle that will have an impact,” Bennett said. “It is also the responses (flushing or avoidance behavior) of the butterflies to approaching vehicles that prevents individuals from crossing over.”
“This got me thinking that there might be some species, perhaps those that are rare, that are more behaviorally sensitive to anthropogenic disturbance and stressors (like the Karner blue). If this is the case this may affect the way such butterflies move across the human-altered landscape.” she said.
Bennett pointed out that butterflies tend to be excellent indicator species. Many are already showing the effects of climate change. Entire populations are shifting ranges to stay in hospitable climates.
“Subsequently, if some species are limited in the way they move across the landscape, how are they going to shift their ranges in light of climate change? To be crude, are we going to lose a number of species simple because they can’t cross a road?”
After the spring field season, Bennett plans to analyze all the data gathered on her “rare” and “common” species to see which species are more sensitive than others. Using this data she hopes parameterize her computer model, so she can simulate the movement of virtual butterflies across a virtual landscape.
“From this we should be able to predict whether each species will be able to shift their ranges. But it’s all a big mystery right now.” she said.
Contact reporter Nancy Raskauskas at 541-758-9542 or firstname.lastname@example.org. Follow her on Twitter @NancyR10.