A quick glance at a winter weather forecast is enough to make most of us grateful for our warm homes and thankful for those who work outdoors in these brutal conditions.
For the wildlife in our communities, theres no escaping the harsh realities of winter. In fact, many of these animals must spend time each day out in the snow and ice to find the food necessary for survival. Take Canada geese, for instance. They are a familiar site at our local lakes and ponds, whether they are frozen solid or not. How do they do it?
Like people and all mammals, birds are warm-blooded. Their body temperature remains constant about 106 degrees, according to the Audubon Society. To maintain their body heat in freezing temperatures, their bodies have developed several mechanisms.
For geese, ducks and other waterfowl that spend time on ice or in cold water, keeping their legs and feet warm is essential for survival. These animals rely on a vascular system designed with this in mind. The arteries and veins in the legs and feet of these birds are close together, which allows the blood to be warmed and cooled quickly, the Smithsonian reports.
As warm, oxygenated blood leaves the heart in arteries moving toward the birds feet, it passes in close proximity to veins returning oxygenated blood back to the heart. This allows for a concurrent heat exchange. The exchange allows the warmth from the arterial blood to increase the temperature of the blood returning in the veins, which is colder after circulating to the birds extremities, Popular Science reports.
This heat exchange isnt just used by birds. Squirrels and other mammals that spend time in the snow also keep warm this way. And the science behind it is the same as how fish exchange oxygen in their gills, according to Popular Science.
The heat exchange is just one way birds stay warm in winter. Many birds have a winter plumage with more feathers to better insulate their bodies, the Audubon Society reports. Some species, such as finches, add fat in winter to both better insulate themselves and provide an energy source.
Many small birds, though, cant bulk up too much because it would affect how they fly. For these birds, such as chickadees, shivering helps them stay warm. Shivering in birds isnt quite like it is for humans. When birds shiver, they are able to activate particular muscle groups that work in opposition to one another. According to the Audubon Society, this causes muscle contractions that allow the birds to better retain their body heat.
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Given that dinosaurs were reptiles with cold blood, how did birds become warm-blooded if they derived from them?
Modern-day birds descended from a group of dinosaurs called theropods.
One of the most famous theropods, the Tyrannosaurus rex, has a hind leg that resembles a large chicken leg. It has four large toes, three pointing forward and one pointing backward, and each is tipped with sharp, curved claws that are compressed from side to side.
More than 250 traits and traits found in the skeletons of theropod dinosaurs and birds are shared by both species.
Like its much larger cousin T, Archaeopteryx, the first bird-like ancestor found, had a long tail and teeth. rex. However, it also exhibited feathers and what appeared to be wings on its forelimbs.
Additionally, according to Dr. Paul Willis, a palaeontologist with ABC’s Catalyst program, it was most likely warm-blooded.
Numerous theropods that resembled birds and had basic downy feathers and hair-like structures can be seen in the fossil record. Willis states that since they were primarily small organisms, “they must have produced their own body heat and evolved hairs and feathers to help retain the body heat they generated.”
Animals have developed two ways to maintain their body heat. One way to produce body heat is through internal thermoregulation; endothermic animals, like birds, use this technique. The alternative is for these ectothermic animals, like reptiles, to absorb heat from their surroundings and store it inside of them.
However, ectothermic animals can still have warm blood despite the fact that we consider them to be cold-blooded. Additionally, their likelihood of maintaining a warm body temperature increases with size.
Because of their larger body mass, larger cold-blooded animals don’t lose as much heat at night as their smaller counterparts, according to studies on crocodiles, a distant relative of dinosaurs. “.
This phenomenon is known as gigantothermy, in which the larger one gets, the easier it is to retain heat.
According to Willis, this means that all large dinosaurs had warm blood by definition.
He continues, “In fact, since heat storage capacity increases with size, eliminating heat and maintaining body temperature must have been a problem for really big dinosaurs.”
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FAQ
Are any birds warm-blooded?
Why don t birds freeze in the winter?
Are chickens cold-blooded or warm-blooded?
Is duck cold-blooded?