Blue Jay
| Scientific Name | Cyanocitta cristata |
| Survival Strategy | Active All Winter |
| Conservation status | Least Concern |
Spring
Blue jays begin building their nest of twigs in mid-March. By late April, four or five eggs are laid, with incubation by the female lasting for 17 days. The hatchlings fledge in 17 to 21 days, and parents will continue to feed the young birds for several months.
Summer
In late summer, blue jays go through a complete molt. This molt is a once-a-year event where every old feather is replaced with a new one. For some jays, the feathers on the head are lost all at once, leaving the bird nearly bald for about a week.
Fall
Caching food for winter is the main activity for blue jays in the fall.
Winter
Mated pairs of blue jays join loosely organized flocks to forage for food in woodlots and bird feeders.
Behavior
Food caching
Blue jays cache seeds, typically acorns, in the fall to provide some of the energy needed to survive the bitter cold of winter. Using a scatter-hoarding technique, they bury seeds a mile or more from where they collected them in locations spread across their territory. Many of the uneaten acorns will germinate and grow into trees.
Migrate, ‘er no?
While most blue jays are year-round residents of the upper Midwest, some will migrate. Ornithologists have not been able to find a noticeable pattern that explains which jays will migrate. Birds that have been year-round residents for years will become migratory for a season or two. Migrating flocks of several hundred blue jays are common.
Physiology
Blue Jays are active in winter in the upper Midwest and often endure bouts of extremely low temperatures. Researchers found that a temperature below -30°C (-22°F) was lethal to 50% of the blue jays studied.
Shivering
A blue jay’s body temperature is about 40°C (104°F). Maintaining that temperature in the winter becomes a matter of life and death. Activities such as flying generate heat and burn calories that may be in short supply. When their body temperature drops, blue jays will begin shivering, which will create some of the needed extra warmth. Unlike humans, birds do not shake when they shiver; instead, they rapidly contract opposing muscle groups.
Feathers
Like most birds, blue jays keep their contour feathers dry by preening oil from the uropygial gland near the base of their tail, ensuring the down layer next to the skin stays dry. When down feathers get wet they do not insulate well. By fluffing their contour feathers (piloerection), the bird traps air that increases the insulation value of the down layer and reduces the number of calories needed to survive the cold.
Weather Prediction
An organ inside the ear of a blue jay called the paratympanic organ detects changes in barometric pressure, signaling a shift in the weather. This ability helps explain why they seem to go on a feeding frenzy before a storm.
Not Falling Out of Bed
Blue jays prefer to sleep hidden in dense evergreen trees, which shelter them from wind and the eyes of nighttime predators. When a blue jay (or most other perching birds) sits down on a branch, flexor tendons in its foot tighten. The pull of the tendons forces the toes to lock around the perch. As long as the bird is sitting, it can’t fall off a branch even if it is sleeping.
Diet
Blue Jays are omnivores. Their diet includes insects, acorns, soft fruits, seeds, bird eggs, and small vertebrates.
Defamation of Character
Although they have a reputation as nest robbers, an examination of the stomach contents of 530 blue jays found only six with any traces of bird eggs or nestlings. John James Audubon’s blue jay painting (Plate 102, Blue Jay) and his anthropomorphic description of these birds as thieves with no morals may have slandered the blue jay in the same way the story of “Little Red Riding Hood” slandered the wolf.
Lifespan and Mortality
Most blue jays live about seven years. 53% of adult blue jays survive each year, while less than half (45%) of the juvenile birds survive their hatch-year. One blue jay, banded in Newfoundland in 1989, lived almost 27 years.
Predators
Nestlings are preyed on by squirrels, domestic cats, snakes, American crows, other jays, raccoons, opossums, and birds of prey, such as hawks. Hawks, owls, falcons, and domestic cats feed on adult blue jays.
Disease
As part of the crow family (Corvidae), jays are particularly susceptible to the West Nile virus.
Climate Vulnerability
The range of the blue jay will likely remain stable in a warmer climate. Spring heatwaves may impact nesting success.
Never stop learning
The feathers of blue jays have no blue pigment. The refraction of blue light by nanostructures on the surface of the feather barbs creates a beautiful blue color.
References
| Smith, K. G., K. A. Tarvin, and G. E. Woolfenden (2020). Blue Jay (Cyanocitta cristata), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.blujay.01 |
| Blue Jay: Audubon Field Guide https://www.audubon.org/field-guide/bird/blue-jay |
| Frysinger, J. 2001. “Cyanocitta cristata” (On-line), Animal Diversity Web. Accessed November 10, 2021 at https://animaldiversity.org/accounts/Cyanocitta_cristata/ |
| Blue Jay, John James Audubon’s Birds of America, Courtesy of the John James Audubon Center at Mill Grove, Montgomery County Audubon Collection, and Zebra Publishing. https://www.audubon.org/birds-of-america/blue-jay |
| Unusual Birds – FeederWatch (bald-headed birds) https://feederwatch.org/learn/unusual-birds/#bald-headed-birds/ |
| The Complete and Total Truth Behind Why Are Blue Jays Blue https://www.birdinformer.com/why-are-blue-jays-blue/ |