With their stunning blue color and reputation for bringing joy and optimism, bluebirds have a special place in human culture. What better subject for a research project during the pandemic? Allison Cornell, assistant professor of biology at Penn State Altoona, has been studying nestling development in wild bluebirds and observed the young leaving their nests usually at 15 days but some took as long as 21 days. “I started to get interested in how diet might be playing a role in that,” she says, and so she began studying bluebirds’ eating habits.
In order to observe the birds at mealtime, Cornell says, “we put Go Pro cameras in over 50 bluebird nests to identify which arthropods (insects and spiders) are being brought back to the nest.” What is clear from their observations is that “the chicks at different nests are getting really different diets.”
What is the reason for that difference in diet and does it have any impact on the bluebirds’ nutrition? Cornell’s work has just been awarded a research grant from the National Science Foundation to study those questions. The grant application explains: “A growing body of evidence suggests that the specific nutrient composition of food may be a more important driver of foraging behavior in wildlife. Because nutrient composition varies with environmental conditions, climate change is likely to affect nutrient content of food. For predators, this means that a changing climate could alter the nutrition of their prey and, therefore, what prey they select.”
The research project has two parts. First, Cornell will be examining the macronutrients—proteins, fats, and carbohydrates—in the birds’ food. “We’re going to be collecting food items from the birds—taking one meal from each one—and we’re going to analyze it for different macronutrients.” For this part, she’ll be working with Publius Vergilius Maro Professor of Entomology Dr. Christina Grozinger, who “studies nutritional ecology in bees. With her expertise, we’re going to quantify macronutrients in the prey (which are protein rich, etc.). We’re trying to figure out if the nutrition levels of different prey even out or if some chicks are getting different quality diets overall (i.e., more protein, and so on).”
The effects of climate change play a large role in the second part of the research. “We’re looking at environmental conditions and how they affect nutritional content,” Cornell explains. “There are a lot of components that we’re testing. Other studies have shown that environmental conditions affect nutritional value of insects; for example, other studies show that rearing crickets at warmer temperatures results in lower protein, but beetles reared under warmer temperatures have higher protein. We’re going to rear the prey under different environmental conditions in the lab and see how their nutritional value changes, and then give the wild bluebirds a taste test to see what they prefer. I hope the results will help us make better predictions about how climate change will affect birds and their prey.”
Cornell expects this research to continue for three years and she is planning to include undergraduate students. “Every summer three to five students will be needed for a field crew. The grant covers the cost of providing summer housing and stipends for these undergrads. Students in my upper-level ecology classes will be rearing prey and analyzing bird feeding videos. The students will get to develop their own research questions. Students with the top eight projects—four from each undergraduate course—will be given the opportunity to attend a national conference, all expenses paid.” Students interested in working on the 2024 summer field crew can apply here.
—Therese Boyd, ’79