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 The Northern Avian Physiology (NAP) lab at Northern Michigan University explores the physiological mechanisms supporting astounding feats in birds–ranging from long-distance migratory flight to survival in frigid winter temperatures–to better understand resilience to environmental changes.

How do environmental challenges shape performance?

Migratory birds, such as Blackpoll Warblers shown here, must respond to many different environmental cues, including habitat availability, temperature, light cycles, and endogenous metabolic cycles and toxins.
From temperature swings to toxins, layering extra stressors on an already demanding lifestyle can profoundly influence a bird’s performance, survival, and reproductive success.

Migratory birds face numerous environmental challenges in order to exploit seasonal habitats to breed. Through a series of exhausting long-duration migratory flights, these birds must respond to light cycles, hot and cold temperatures, changing habitats on the landscape, optimal food availability, predators, toxins, and so much more. This makes migratory songbirds a great system to study the ways that physiological flexibility on the knife’s edge can support this incredible lifestyle!

What are the secrets of physiological flexibility?

Migratory birds are masters of renewal, repeatedly breaking down and rebuilding their bodies across their journeys, and their recovery from such intense cycles of remodeling can reveal secrets to endurance and resilience.

The challenges of migration don’t end when a bird lands. Their bodies change so drastically in flight that they must then quickly reorganize their metabolism to gain the most from the food sources that are available. This raises many questions about the extent of physiological damage they can incur in flight and how they have evolved to bounce back, from pre-emptively preparing to cope with the damage, choosing the right food sources, or even harboring microbiota that support flexibility.

Which molecular pathways unlock resilience?

SERCA pumps calcium into the sarcoplasmic reticulum using ATP. With the uncoupling protein SLN, this leads to less efficient pumping and more heat production.
From the environment down to the cell, resilience is built on molecular flexibility, and birds may reveal fundamental mechanisms that can sustain health and performance in both wildlife and humans.

Wasting energy seems like a bad idea if you’re a bird! For example, up to half of an animal’s resting energy use can be attributed to the cost of calcium regulation in muscle. Calcium can signal for wide-ranging physiological changes with broad implications for organismal health, such as fuel use, exercise capacity, obesity, and heat generation, so it’s vital that it be carefully regulated. Some proteins, such as sarcolipin (SLN), can cause wasteful activity of the calcium pump SERCA and generates excess heat as a byproduct. The potential for this heat-generating but energy-consuming process to play a role in birds is a fascinating area of exploration!

Flexible responses in a changing world

Because an animal’s genetic toolkit is limited, the potential to entrain physiological changes to different environmental stimuli may enable a broader range of responses to environmental variation and therefore greater resilience in a changing world. We take a holistic approach to understand how physiological flexibility at all levels has evolved in these incredible species.