Urdaibai ospreys reveal the secrets behind thermoregulatory adaptations in this species

Svana Rogalla, PhD student at Gent University, has recently published an interesting scientific paper about the ospreys that formed part of the restoration program by the Urdaibai Bird Center.

The osprey is a migratory raptor that is distributed all over the world. The juvenile ospreys of Urdaibai perform an incredible long migration from the Basque Country to Senegal. Crossing the Sahara Desert, they are confronted with extremely high ambient temperatures. Other than mammals, birds cannot sweat, which means they depend on other mechanisms to prevent from overheating. To understand how these juvenile ospreys cope with heat stress, we used a thermal camera and measured surface temperatures of the young birds in the hacking tower. Surface temperature measurements can help us understand heat exchanging mechanisms that are taking place. For example, a surface that is colder than the surrounding environment gains heat, while a hotter surface dissipates heat. The thermal images of ospreys showed that the bill, legs and claws were always hotter than the surrounding air, indicating that those body parts serve as heat dissipation areas.

The larger legs and claws played a more important role in the birds' total heat exchange than the small-sized bill. Surprisingly, the thermal images revealed that some ospreys developed a colder stripe on the head at high ambient temperatures, probably indications for a cooling mechanism based on water evaporation through the skin. Further behavioral observations revealed that the young ospreys prevented overheating by panting or opening their wings to dissipate body heat from the less insulated ventral side.

Learning about the heat coping strategies applied by juvenile ospreys can improve our understanding of how these birds can cope with extremely high ambient temperatures, for example when crossing the Sahara Desert. It might further provide some insights in how ospreys might cope with the increasing temperatures and more frequent heat waves that will come with climate change. 

For access to the article on heat exchanging mechanisms in ospreys, please look here: https://authors.elsevier.com/a/1cTci15hXu4iKp

We, at the Urdaibai Bird Center, are proud that our osprey restoration program contributed to scientific data collection leading to publications as interesting as this one.