Study Suggest Tiny Birds’ Blood Gets Warmer in Winter

Jun, 2021 - By WMR

Small birds can do more than fluff up their feathers to keep warm on chilly winter days. They can actually make their blood run hotter, producing a type of central heating mechanism, according to new studies.

Endotherms or so-called warm-blooded animals in chilly areas improve heat‐producing capacity while planning for winter. Small birds may do more than fluff up their feathers to remain warm on chilly winter days. Hence, scientists from Scotland's University of Glasgow and Sweden's Lund University, examined the progressions of mitochondrial work in red platelets in sympatric Great (Parus major), Blue (Cyanistes caeruleus), and Coal (Periparus ater), tits among fall and winter. These species contrast more than twofold in weight and in a few parts of their social dominance and foraging ecology, which could require differential seasonal transformation of energy use. Great and coal tits specifically unregulated the mitochondrial volume and mitochondrial respiration rate in winter. This was not coordinated toward ATP combination, rather reflecting increased uncoupling of electron transport from ATP creation. Since uncoupling is exothermic, this expanded heat‐producing limit at the sub‐cellular level in winter. This already neglected the course of thermogenesis in birds ought to be addressed to in future work.

Blood samples were taken from great tits, coal tits, and blue tits in early autumn and late winter in a recent study conducted by Sweden's Lund University and Scotland's University of Glasgow. The researchers removed red blood cells from the samples and then looked at their mitochondrial function. Mitochondria are subcellular structures that can either produce muscle energy or generate heat. The scientists were able to determine how much oxygen the birds' mitochondria consumed by using a respirometer, which enabled them to determine if the mitochondria were producing energy or heat.

The mitochondria were found to be used more to generate heat in the winter, which was surprising because it has long been thought that small birds have a higher metabolism in the winter, which would necessitate a greater expenditure of physical energy. Furthermore, it was discovered that there were more mitochondria in the red blood cells during the winter.

The researchers now want to see if the change in mitochondrial function is caused by the cold weather itself, or if it's caused by other factors including seasonal dietary changes.