In the world of birds, there are others that can wreak similar havoc on their nesting neighbours. I have seen Red-bellied Woodpeckers predate on eggs in a bluebird box. The tiny House Wren is notorious for removing eggs of other cavity nesting birds so they can acquire the use of the ready-made housing for themselves. Birds can become combative among their own species or others to protect and defend territories and food resources. Birds can become aggressive among themselves in search for a mate from simple displays and posturing to driving off other suitors. It’s an evolutionary process of the survival of the fittest.
Blue Jays are omnivores. They will glean the ground, shrubs, and tree branches for insects, nuts, and seeds. A quarter of their diet consists of insects with acorns, nuts, fruits, and grains making up almost the entire remainder of what they consume.They have been known to take small vertebrates that are dead or injured.
Blue Jays like to build their nests in the crouch of deciduous trees and conifers about ten to twenty feet above the ground. Both the male and female gather materials and build the nest, but on average the male does more gathering of materials and the female more of the nest construction. Twigs from live trees are used in outer part of nest. They often struggle to break these twigs off. The nest is finished with rootlets and grasses. They may fly great distances to obtain rootlets from recently dug ditches, fresh graves in cemeteries, and newly fallen trees. Unfortunately Blue Jays may abandon their nest after detecting a nearby predator.
The normal clutch is four or five eggs, which take seventeen days to hatch. Only the female incubates the eggs while her mate provides all her food during this period. Even for the first 8–12 days after the nestlings hatch, the male provides food for his mate and the nestlings as she continues to brood the young after which she will help to gather food. The young will remain in the nest for up to 20 more days before they fledge. The adults will continue to feed them for an additional 30 days or more although the young may continue to beg for food well into late summer. The family unit will stay together for several months.
Many ask how to tell the sexes apart? They look identical to us, but they obviously know the difference. There are two times when we can tell them apart and the first is, when the early spring chases ensue. A number of noisy Blue Jays will be flying about and the lead bird will be the female, followed by her suitors. The other is if you are lucky enough to find a nest, as it will be the female sitting on the eggs.
A raucous flock of Blue Jays have always reminded me of a bunch of unruly teenagers, bent on having a good time. They are especially noisy in late winter and spring. When they are paired and courting, prior to nest building, they become very quiet and stealthy. They lurk through the forests like blue ghosts, barely making a sound. When the nest is built and the eggs are laid, they seem to become their noisy selves once again.
Blue Jays use both vocal and “body language” to communicate with one another. While incubating a clutch of eggs, feeding the nestlings, or associating with mate, family, or flock mates, the crest of the Jay is laid down. You can tell the aggressiveness of a Blue Jay by looking at how they are holding the crest on their head. The lower the crest the less aggressive they are. The higher the crest is raised demonstrates a more aggressive attitude. Vocalization of Blue Jays has a wide vocabulary and is very diverse. They are excellent mimics as well. They are known to mimic the call of a Red-tailed hawk and even other species.
Blue Jays are partial migrants. Some may stay in an area year around, The proportion of jays that migrate is probably less than 20 percent. However some years they may be more sparse. A poor acorn crop will force many to migrate to better food sources in other areas. These birds will then return about the first of April, to start this whole nesting thing all over again.
The Blue Jay population has decline about 29% between 1966 and 2014 according to the North American Breeding Bird Survey. The most frequent cause of death associated with human activity comes from attacks by cats.
Fun Blue Jay Facts (From the Cornell Bid Lab’s All About Birds)
- Thousands of Blue Jays migrate in flocks along the Great Lakes and Atlantic coasts, but much about their migration remains a mystery. Some are present throughout winter in all parts of their range. Young jays may be more likely to migrate than adults, but many adults also migrate. Some individual jays migrate south one year, stay north the next winter, and then migrate south again the next year. No one has worked out why they migrate when they do.
- Blue Jays are known to take and eat eggs and nestlings of other birds, but we don’t know how common this is. In an extensive study of Blue Jay feeding habits, only 1% of jays had evidence of eggs or birds in their stomachs. Most of their diet was composed of insects and nuts.
- The Blue Jay frequently mimics the calls of hawks, especially the Red-shouldered Hawk. These calls may provide information to other jays that a hawk is around, or may be used to deceive other species into believing a hawk is present.
- Tool use has never been reported for wild Blue Jays, but captive Blue Jays used strips of newspaper to rake in food pellets from outside their cages.
- Blue Jays lower their crests when they are feeding peacefully with family and flock members or tending to nestlings.
- At feeders in Florida, Red-headed Woodpeckers, Florida Scrub-Jays, Common Grackles, and gray squirrels strongly dominate Blue Jays, often preventing them from obtaining food.
- The pigment in Blue Jay feathers is melanin, which is brown. The blue color is caused by scattering light through modified cells on the surface of the feather barbs.
- The black bridle across the face, nape, and throat varies extensively and may help Blue Jays recognize one another.
- The oldest known wild, banded Blue Jay was at least 17 years, 6 months old when it was recaptured and rereleased during banding operations in Ohio.
This common, large songbird is familiar to many people, with its familiar crest; blue, white, and black plumage; and loud noisy calls. Blue Jays are members of the Corvids, known for their intelligence and complex social systems. They maintain tight family bonds. Their fondness for acorns has given them the nickname of the “harvester bird”. Their caching away of nuts has been spreading oak trees since last glacial period.
The Blue Jay and the Crow have the reputation of being the sentinels for danger in the world of birds. When a flock of noisy Jays come into your feeding area, most birds scatter or head for cover. Many think it is the Jay itself that causes this. Occasionally they may sound the alarm to free-up space for themselves at overcrowded feeders, but more often it is a call that alarms not only other birds in the area but many mammals in the vicinity of a nearby predator such as a hawk, fox, or cat. Squirrels will rush for the trees and even deer seem startled by the alarm.
Blue Jays are considered by many to be nest robbers. But of 530 stomachs of Jays examined by researchers, looking specifically for every possible trace of bird remains, only 6 stomachs had traces of bird eggs and nestlings found in them.