Just like bluebirds, Blue Jays have no blue pigments in their feathers. Instead, each feather barb has a thin layer of cells that absorb all wavelengths of color except blue. Only the blue wavelength is reflected and scattered, resulting in their blue appearance to our eyes.
Blue Jays are often chastised for their known practice of eating eggs and nestlings of other birds. But extensive research has proven this to be a very rare occurrence, with only 1% of the study population showing any evidence of this behavior.
Blue Jays are known to migrate, but the phenomenon is not well understood by scientists. Research has shown that some individuals will migrate south during some years and choose to stay in the north during others. Why they do this is still one of nature’s mysteries.
It is estimated that only about 20% of the population of Blue Jays migrate, even in the northern parts of its range.
Many migrating Blue Jays reach their wintering grounds after natural food crops, such as acorns, may have already peaked. Whether they still cache a winter food supply is unknown at this time. Birdfeeders may play an important role for some of these birds.
Most migratory flights by Blue Jays begin about an hour after sunrise and cease by noon. The average migrating flock contains 10 -30 birds.
Peanuts in the shell are a favorite among Blue Jays. Watch your feeder to see if you can observe them shaking peanuts to tell if the shell is full or empty.
Blue Jays eating acorns alone quickly start to lose body mass, unless those nuts are full of protein-rich weevils or supplemented with other sources of insect protein.
Blue Jays mainly select undamaged nuts to bury; research has shown that only 10% of the acorns they cache are not viable seeds.
Blue Jays will bury seeds up to 2.5 miles from their original source, which is a record for any bird. This behavior has greatly helped with the range expansion of many oak species.
The rapid northward dispersal of oaks after the ice age may have resulted from the northern transport of acorns by Jays.
Due to Jay’s habit of burying acorns over a wide area, 11 species of oak trees have become dependant on Jays for the dispersal of their acorns.
Research studies have recorded Blue Jays making over 1,000 trips per day when hiding food.
In one research study, 50 Blue Jays were observed selecting and caching 150,000 acorns over a period of 28 days. Each bird cached a total of 3,000 acorns by selecting and hiding an average of 107 acorns per day.
In one research study, Blue Jays were observed storing over 2,000 beach tree nuts in one month.
A Blue Jay was observed packing over 100 sunflower seeds into it’s gullet during just one visit to a feeder.
The Blue Jay is a talented mimic; its version of a Red-shoulder hawk’s call can fool even the most experienced birder.
An old folktale says that the Blue Jay was yoked to a plow by a sparrow and the mark it left behind is still visible today on the Blue Jay’s neck and chest.
Jays will cache seeds and nuts to retrieve later, and make repeated trips to feeders to gather food and hide it in a safe spot.
Blue Jays are known to migrate, but the phenomenon is not well understood by scientists. Research has shown that some individuals will migrate south during some years and choose to stay in the north during others. Why they do this is still one of nature’s mysteries.