Mary Alice and I have been watching a bald eagle’s nest and wondering whether the young eaglets had hatched out as yet. The game commission’s Breeding Atlas stated that the eggs are laid between March 31 and April 17, with the eggs hatching 35 days later.

The young will begin to fly within three months. In the autumn, the young will leave their parents’ care and be on their own.

Although our bald eagle population has been increasing and sightings are not as rare, Mary Alice and I are still excited when we see one. The name bald is a misnomer because the bald eagle’s head is covered with white feathers.

We are coming to the time of the year when most wildlife will be having their young. Some young wildlife will not require care and are on their own as soon as they are born or hatched out, however, others will require weeks if not months of tender loving care from their parents.

Some animals are perfunctory parents and will have mass production of young, which have instant maturity. The female milk snake buries her elongated, leathery eggs, allowing the sun to do the hatching. The young emerge as miniature adults, capable of finding food on their own.

There are two systems that wildlife use: precocial and altricial. Precocial comes from the Latin word praecox and means to ripen beforehand. In this type of hatching process, the birds spend a long time inside the egg (about one month), however when they hatch out, they are fully feathered (usually covered with down) their eyes are open, and they can leave the nest within one hour.

These birds, which are usually ground nesters, fear predators and cannot afford to have their young in the nest for very long. Their chance of survival is greater if they leave the nest right away. Precocial is an adjective describing an animal that is ready to take care of itself immediately after birth. For example ducks, geese and most ungulates, including deer and antelope, are in the precocial group.

Although in the case of deer and other mammals, the young will continue nursing for several months and may enjoy the company and protection of their mothers for a year or more, so taking care of itself could be an exaggeration.

The other hatching process is known as altricial, which is also Latin and comes from the Latin word altrix, meaning nurse or wet nurse. It is the term used for young birds that hatch in a helpless condition. These young are hatched out as soon as possible, usually, 12 days. The chicks are only half formed, with no feathers and closed eyes. They are very weak and helpless, surviving the first few hours on the egg yolk that their stomachs have absorbed.

It is estimated that less than one third of the very fragile altricial born birds survive to maturity. Altricial parents will have two and sometimes three sets of young in one mating season. Altricial means the opposite and describes an animal born helpless and in need of much care. Examples are mice, squirrels, bears and the American robins.

The young of the bald eagle are a perfect example of the altricial system. After the young are hatched, the parents attend to them until the end of summer when they fledge from the nest.

Perfect examples of precocial birds are the turkey and grouse. Both birds nest on the ground, with egg hatching taking almost a month (24 days for grouse and 28 days turkeys). The young will brood under the mother until able to fly short distances. In turkeys, this is about two weeks.

If danger threatens the young grouse chicks, the female will give out a loud squeal and the young will hide. The female might do a crippled-bird act in an effort to lead the intruder away. Within seven days, these young are able to fly to a perch about a foot above the ground and in 10-12 days, they fly well enough to roost in trees with their mother.

Most songbirds are altricial birds. In this system, raising young can be exhausting for the adult birds. The altricial birds usually take about two weeks to hatch out the eggs, and the young are in the nest about fourteen days. During this period, the parents must provide food for the young from dawn to dusk. It was recorded that in one day, a pair of wrens made 1,217 trips to the nest, while carrying food for their young.

A young robin can eat up to 14 feet of earthworms in a day and with three or four young in the nest, the parents are constantly bringing food to the young.

Mammals also have a tough time raising their young. While in the den, the female black bear usually gives birth to her cubs in either late December or early January. She will nurse the cubs for the next three or four months. During this period, the female bear will not eat, drink, defecate or urinate. The young cubs are content to nurse and sleep for the first few weeks.

After four weeks, their eyes open. Later, they start to move about, and paw prints are sometimes seen in the mud and snow outside the den. The female will leave the den when the cubs are about three months old. She protects them by sending them up a tree if danger threatens. The cubs have no real enemies in the wild, except for man and the adult male bears, which have been known to kill and eat cubs.

The cubs will stay with their mother until their second summer, at which time, the family unit breaks up.

Now compare the bear to the cottontail rabbit, which is food for many predators. For the species to survive, rabbits depend on the capability of multiplying at an alarming rate. The doe gives birth to the young in a cup-shaped nest that she has scratched out on the ground. The nest is lined with dried grasses and fur pulled from her belly and breast. By pulling out fur, the doe exposes her mammary glands, making it easier for the young to nurse.

The young rabbits are born blind, hairless and helpless, however, they develop rapidly, with their eyes opening within five days. After about 16 days — perhaps as early as ten — the young are weaned, fully furred and on their own.

During this time, the female is beginning another nest. In one study, it was found that the typical female bore twenty-five young over the course of a year. Juvenile females born in the early spring are sexually mature by late summer. They often mate and raise a September litter.

About 85% of all young cottontails never reach maturity with few living more than a year in the wild. However, their lifespan in captivity could reach ten years.

We will soon be seeing young wildlife, and although they might appear as if they need help the best thing you can do to help is leave them alone.

Bill Bower is a retired Pennsylvania Game Commission Wildlife Officer. Read his blog and listen to his podcasts on the outdoors at www.onemaningreen.com.