The birds and the trees
MARQUETTE — Who knew that studying the connection between insects, birds and trees could end up being like a chemistry experiment?
Birds eat insects from some trees, yet leave others untouched. Why? It could be that when the insects begin to munch on leaves, the trees send out a “help signal” — chemicals the birds can “smell.”
This scenario is the basis of thesis research being conducted in Marquette County jack pine stands by Northern Michigan University biology master’s student Katie Bjornen.
Bjornen recently won several competitive research grants and presented her work Aug. 2 at the joint meeting of the American Ornithological Society and Society of Canadian Ornithologists in East Lansing.
Preliminary results from her work indicate that birds might prefer some trees over others for foraging, that there is an unexpected amount of variability in the volatile compounds released by the trees, and that in fact birds are attracted to trees that release certain volatile chemicals.
Bjornen got the idea for her study after reading about native and non-native plants, and learning that native plants attracting more birds.
She also learned more about those volatile organic chemicals that trees release.
“They’re releasing chemicals when they’re being attacked by insects, both to repel insects and also to actually signal to other trees that it’s being attacked by insects,” Bjornen said. “So, they’re talking to each other.”
Unlike a cartoon, however, biologists can’t read speech balloons from trees, mainly because they don’t exist.
So, research like this is needed.
“It’s going to make sense for a bird to go to a tree that has higher insect abundance, you know, because it’s more efficient,” Bjornen said.
She noted birds simply could be seeing insect damage and then just going on that.
Bjornen said that a few prior studies performed in lab conditions, though, indicated that might not be the case, and that birds could detect volatile chemicals released by deciduous trees. However, her study is the first to look at wild birds foraging on coniferous trees under natural conditions.
“I’m just figuring this out by measuring foraging time on trees and then measuring what volatiles those trees are releasing are,” Bjornen said.
She noted she is looking at whether trees with higher foraging have different volatile compositions or different amounts of volatiles being released.
“I’m just looking for differences between higher foraging and lower foraging,” Bjornen said.
This involves working with the NMU Chemistry Department with gas chromatography-mass spectroscopy, which is shortened to GCMS for obvious reasons, she said.
A machine is showing different levels that indicate volatile identity, she said.
“Katie’s research may provide lots of exciting insights on avian ecology,” said her adviser, NMU biology professor Alec Lindsay, in a news release. “For starters, the conventional wisdom has been that most bird species don’t use olfactory cues in their everyday lives, but Katie’s work adds to the evidence that indicates otherwise.
“Additionally, since she is looking at this phenomenon in jack pine stands, the outcomes of her work may have important implications for managed commercial forests, and for the conservation of Kirtland’s warblers — an endangered species of bird that requires young jack pine stands for breeding habitats.”
Bjornen said understanding what is drawing birds to a forest type can be important, and changing volatile chemicals to eventually “trick” the birds into going to different locations can be beneficial to a commercial forest.
“Birds significantly decrease the amount of insect damage to trees,” Bjornen said. “They really help trees out.”
She agreed that Kirtland’s warblers, which according to the Michigan Department of Natural Resources breed mainly in young jack pine forests where the soil type is well-drained Grayling sand, could benefit from her research.
“You have to manage them very heavily in order to make good habitat,” Bjornen said.
Bjornen obtained her bachelor’s degree in organismal biology from Montana State University in 2014. She will finish her master’s degree at NMU this fall, and complete her study by December, with the hope it will be published in a scientific journal.
The love of birds runs in her family. She first become interested in birds and birding by tagging along during the research performed by her parents, both ornithologists in Montana.
“Part of it is almost game, because it’s fun to learn what the species are, and then starting to realize how many there actually are, you know, just what you would see around you,” Bjornen said. “And it’s fun and I just love being outside, so it kind gives me an extra thing to go out and look for.”
While an undergraduate student and since, Bjornen has held positions conducting avian ecology research for various agencies and consulting companies. Since arriving at NMU, she has been involved in several bird research projects and served as a teaching assistant for ornithology classes.
Bjornen’s research has received funding from competitive research organizations including the Paul A. Stewart Award from the Wilson Ornithological Society and the Grant in Aid of Research from Sigma Xi — the International Scientific Research Honors Society. She also has received funding through the William Robinson Award from the NMU Foundation and the Excellence in Education award from NMU.
After Bjornen graduates, she plans to gain more work experience for a couple of years and then enter a Ph.D. program. Following that, she’d like to teach students in a university setting.
“I really enjoy working with students, and getting them excited about research is one of my main goals,” Bjornen said.
Christie Bleck can be reached at 906-228-2500, ext. 250. Her email address is firstname.lastname@example.org.