Blue Jay

Not actually blue

Blue jay feathers contain no blue pigment. The blue color is structural — produced by the way light scatters off microscopic structures in the feather barbs. If you grind a blue jay feather to dust, the dust looks brown, not blue.

This is the same physics that makes the sky and many blue eyes blue — Tyndall scattering — and the same effect that produces structural color in peacock train feathers, blue morpho butterfly wings, and beetle elytra.

A corvid mind

Blue jays are members of the corvid family — the same family as crows, ravens, and magpies — and share the family’s reputation for high intelligence. Documented blue jay behaviors include:

• Tool use — using sticks, paper, and even paper clips to retrieve food.
• Counting — distinguishing between sets of objects up to about 7.
• Memory — remembering the locations of hundreds of cached acorns through a winter.
• Long-term recognition of individual humans, including ones who have helped or harassed them in the past.

Acorn dispersers

Blue jays are major dispersers of oak trees across North America. A single jay can cache up to 5,000 acorns in a single autumn, burying them individually in soil within several kilometers of source trees. The jays remember most cache locations but not all — uneaten acorns germinate, often dozens of them per individual jay’s effort.

Genetic studies suggest that the rapid northward expansion of oak forests after the last Ice Age — which moved faster than wind dispersal alone could explain — was largely accomplished by jays carrying acorns ahead of the retreating glaciers.

Hawk mimicry

Blue jays are accomplished mimics. Among their imitated calls, the screech of a red-shouldered hawk is the most common. They use the imitation strategically:

• As a warning to other jays — when a real hawk is present.
• To clear backyard feeders — scaring other birds away so the jay can eat alone.
• As deception during raids on other birds’ nests.

The call is convincing enough that experienced birdwatchers regularly mistake it for a real hawk on the first hearing.

Pair bonds

Blue jays form long-term, often lifelong pair bonds. Pairs build nests together, with the male feeding the incubating female on the nest. Both parents tend the nestlings. Family groups often stay together for several months after fledging, with adolescent jays helping parents as the next clutch is raised.

A range expansion

Blue jay range has been expanding westward over the past century. They’ve moved into the Great Plains, the Rocky Mountain front range, and the Pacific Northwest in recent decades. The probable cause: bird feeders and ornamental oak plantings creating year-round food in territory that previously had neither.

Their westward push is bringing them into contact with the closely related Steller’s jay (Cyanocitta stelleri) of the western mountains. Hybrids have been recorded in the contact zone — likely the same evolutionary outcome that produced both species from a common ancestor in the Pleistocene.