On this National Bird Day, let’s dive into some fascinating research about one of nature’s most amazing species: hummingbirds. Last spring, Dr. Derrick Groom and his team in The Avian Energetics Lab at San Francisco State University, including students Cecilia Doan and Christian Guerzon, presented their research at the 2024 American Physiology Summit. Their study explored how these tiny birds manage water loss in a warm environment (30 degrees C).

Dehydration is a major threat to animals living in hot environments. As temperatures soar, animals lose water through two main processes: evaporation from the skin (like sweating) and through breathing or panting. While evaporation can help cool the body, such processes also lead to water loss, a precious resource for survival in the heat. For small animals like hummingbirds, this problem is even more pressing. Their high surface area to volume ratio means their skin may play a big role when it comes to water loss through evaporation.

Hummingbirds are primarily nectar feeders, and nectar isn’t just sweet – it is a great source of water. But, as with any fluid intake, excess water must be disposed of either in their urine or through evaporative water loss. Dr. Groom’s team wondered how the skin and respiratory systems of hummingbirds responded after they ate a meal of nectar in a warm environment. After feeding, Anna’s hummingbirds (Calypte anna) lost nearly twice as much water through evaporation as compared to when they were fasting. While both the skin and respiratory systems were responsible for nearly identical amounts of water loss after feeding, the increase in water loss was only significant for the respiratory system.

Understanding how birds and other animals adjust to changes in their environment is important in efforts to promote their health and conservation.

Source:

C Doan, C Guerzon, D Groom. Comparing the contributions of cutaneous and respiratory evaporative water loss to cooling in Anna’s hummingbirds (Calypte anna) under fasted and fed conditions. Physiology. 39(S1), 2024. doi: 10.1152/physiol.2024.39.S1.1256.

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Categories: Climate Change, Environment, Extreme Animals, Physiology on the Road

Tags: American Physiological Society, American Physiology Summit, bird, birds, dehydration, health, heat, hummingbird, National Bird Day, nature