As the aspens begin to change color and a cloud of condensation follows every breath, we know that winter is on its way. With the arrival of ski season comes the departure of some of our most beloved birds who fly south in search of warmer weather. However, there are a few resilient residents that just can't seem to get away from the mountains, and the jays are among these few.
Jays are medium-sized perching birds that belong to the crow family, Corvidae, which also includes the Clark's nutcracker, black-billed magpie, American crow and the raven, all residents of the Eagle Valley. The two species of jays that you will most commonly see here in the valley are the Steller's jay and the gray jay, who are able to survive the cold winters because of their unique adaptations.
There are a number of physical modifications that these birds have adopted to brave the cold winter, including the ability to control blood flow to their extremities in order to limit heat loss. The jays will also grow extra feathers during their late fall molt to help insulate them in the coming months. Lastly, like many mammals, birds will overindulge on fall abundance so that they build up extra fat reserves to insulate them and provide much-needed energy.
In addition to these physical adaptations, the jays have developed a number of behavioral adaptations that also help them survive winter. Like many other birds, they fluff out their feathers, creating additional air pockets that add to insulation. They also have the ability to crouch, covering their legs and feet from cold air and wind, and will often tuck their beaks into their feathers to keep warm. Birds, like humans, have the ability to shiver, which increases their metabolic rate and generates additional heat.
The average body temperature of birds is 105 degrees Fahrenheit, which can be difficult to sustain when the air temperature drops below zero. Typically, the smaller the bird is, the faster its heart will beat, which means a higher basal metabolic rate, and the faster the heartbeat, the more heat generated. Jays are a medium-sized bird, which means their basal metabolic rate should be slightly lower than that of a small Chickadee. That being said, because they are a wintering bird, their basal metabolic rate is actually about 23 percent higher than that of similar-sized birds that migrate during the winter.
As a species of cold climates, jays can actually enter a state of self-induced hypothermia called torpor, which slows their heart rate and drops their core temperature, similar to an animal in hibernation. Torpor allows birds to lower their body temperature by up to 50 degrees Fahrenheit. This adaptation allows them to survive bitter cold nights, but it can also make them more vulnerable to predators because of their decreased reaction time and level of awareness.
One last factor in explaining the jays' ability to brave the cold winters in the Rocky Mountains is their ability to be opportunistic omnivores. Jays, like all members of the Corvidae family, are extremely intelligent. They feed on both plants and animals and will take advantage of any food available. You'll often see the gray jay atop Eagle's Nest on Vail Mountain, scavenging for bits of food left by patrons.
To increase your viewing opportunities, invest in some bird feeders and stock them with sunflower seeds, peanuts or suet. Just be aware that these feeders will attract other animals looking for scarce sustenance during the coming winter months. Keep your feeders clean and your seed fresh, and enjoy the company of these intelligent and entertaining feathered friends.
Jeff Holobeck was a summer naturalist at Walking Mountains Science Center in Avon. Come visit Walking Mountains Mondays through Saturdays from 10 a.m. to 6 p.m. or join us for a nature hike at 2 p.m. daily.