Protein helps birds prepare to fight off infection

Bird feeding is a cherished pastime across many cultures. Whether it’s scattering breadcrumbs near a city pond or hanging feeders outside suburban windows, millions of people engage in acts of casual care for wild birds.

Recent research from the University of Arkansas reveals that what we feed birds can deeply affect how they handle disease.

The study revealed that canaries on high-protein diets developed stronger immune profiles and milder symptoms when infected with Mycoplasma gallisepticum (MG), a pathogen common in wild songbirds.

“Our results are exciting because of the importance of human supplemented food in wildlife disease systems, especially wild birds, which are commonly provided with supplemental food via bird feeders,” said Erin Sauer, lead author of the study.

This research is the first to link diet with molecular-level immune differences in wildlife. It focuses on how food type – not just quantity – shapes disease outcomes in birds.

Protein-fed birds recover faster

The researchers divided canaries into two groups. One group received a high-protein diet made mostly of egg whites, while the other received a high-fat diet with more yolk and oil. Birds were then exposed to the MG pathogen or given a harmless placebo.

Before infection, protein-fed birds already showed increased expression of immune-related genes. After infection, lipid-fed birds had to ramp up their immune systems, while protein-fed birds maintained steady, high-level expression. This shows their immune systems were already ready.

Protein-fed birds recovered faster. Their eye inflammation – a symptom of MG – was lower and cleared quicker. Lipid-fed birds took longer to recover, with more prolonged symptoms.

Immune gene activity before infection

The team used RNA sequencing to analyze gene activity. Before infection, protein-fed birds had 267 genes upregulated related to immune defense.

Lipid-fed birds had 248 different genes upregulated, many tied to basic cellular functions like ribosome activity, not immunity.

After infection, the contrast grew. Lipid-fed birds showed over 1,000 genes with significant changes. Protein-fed birds had only 66 such genes.

This means lipid-fed birds had to drastically adjust their systems during infection. Protein-fed birds needed little change – they were already prepared.

Surprisingly, immune genes like JCHAIN (linked to antibody production) were seven times more active in protein-fed birds before infection. Lipid-fed birds only caught up after infection, suggesting delayed immune readiness.

Metabolic clues and broader implications

Diet also influenced energy-related genes. Lipid-fed birds showed signs of stress in genes tied to mitochondrial function and insulin regulation.

One gene, LEPR (leptin receptor), responded in opposite ways between the two groups. This points to broader metabolic differences that could influence disease tolerance.

These molecular effects mirror patterns seen in wild house finches that have evolved tolerance to MG. This suggests that simple dietary changes can mimic the effects of natural selection.

What backyard bird lovers can do

So what can people feeding backyard birds take from this study?

Sauer suggests giving birds high-protein and nutrient-dense options. These include suet with seeds, mealworms, peanuts, and sunflower seeds. These foods support birds’ immune systems and overall condition.

Avoid feeding mostly cracked corn, millet, or bread. These offer limited nutritional value. Still, birds may need more fat during winter or migration, so balance matters. Birds will often choose what they need most.

Protein can boost birds’ survival

This study shows that everyday actions, like feeding birds, can directly impact their survival and overall health. While feeding may seem harmless or routine, the type of food offered plays a critical role.

Poor-quality food can weaken birds’ immune systems, making them less able to fight infections and recover from illness.

As human activity continues to reshape natural landscapes and spread disease more widely, our role in supporting wildlife becomes even more important.

The research reminds us that meaningful change often begins with small, consistent habits. Offering nutrient-rich, protein-balanced food helps birds stay strong, boost immunity, and recover faster when sick or stressed.

Even simple choices at backyard feeders, such as selecting better ingredients, can strengthen birds’ natural defenses. These actions become a powerful way to support bird populations.

The study is published in the journal Molecular Ecology.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–