Many years ago my late mother-in-law called me to look at the really cute baby blue jays that were visiting her feeder. She just started feeding birds in early October. I knew she wasn’t seeing young blue jays in the middle of autumn so I asked her to describe them.

“They are a light gray and a cute crest on their head just like the blue jays,” she responded. What she was watching were tufted titmice, which are about half the size of a blue jay.

Some people think that altricial birds (like robins and blue jays) when they leave the nest develop like human children. That’s not quite the story. When robins or jays hatch, they are indeed featherless (some downy feathers) and helpless. But, within about three weeks they have grown to almost adult size, fed by very dutiful and probably very tired parents.

The parent birds exhaustively make trip after trip to the nest with grub for the hungry brood. After about three weeks in the nest the body feathers have grown in, as well as the flight feathers on the wings. At this point they are ready to leave the nest, and save for the shorter tails, the fledglings are almost adult sized.

Precocial birds (like chickens, grouse, turkeys) hatch feathered, and within hours are following the parent bird as she leads them to food and safety. These precocial birds take months to develop to the adult size with enough feathers to fly.

While the fledgling altricial birds may be nearly adult sized, their feathers (overall plumage) are usually not at all like the adults’. One rather extreme example is that of the little blue heron. The adult is a beautiful deep blue color while the first-year bird is all white. Only the tip of its bill is black-tipped like the adult.

Young eastern bluebirds show a hint of the adult’s color and not until they’re about 6 months old do they start looking like the bluebirds with which you are familiar.

A visit to the Jersey shore or Coastal Maryland very early in summer will find you seeing many crisp-looking laughing gulls as well as some ring-billed gulls. However, if you visit there after the end of July, the numbers of these pretty white gulls with black heads are bolstered by their young of the year.

The young of most gulls are adult sized but generally display a very dull grayish-brown color. In most gull species, the molt takes place in late winter, and by their first spring they have attained the prettier adult feathers. Again, remember, gulls are altricial, and when the young are able to fly and leave the nest there is little size difference between the adults and young.

Our raptors, including eagles, are also altricial birds. Spending 60 or 70 days in the nests (eagles) allows the juvenile birds to reach adult size before taking their first flight. A recent column detailed the color differences between adult and juvenile eagles. Humans, though, reach the mature height generally by the late teens or possibly early twenties.

Test Your Outdoor Knowledge: Which of these grosbeak species seen in Pennsylvania, actually breed here? A. pine grosbeak, B. evening grosbeak, C. rose-breasted grosbeak, D. none of these, E. all of these.

Last Week’s Trivia Answer: White-winged crossbills have overlapping beaks to pry open the pine cones in order to reach the seeds.

Contact Barry Reed at breed71@gmail.com.