Fledge is the stage in the life of a young bird when the feathers and wing muscles are developing for flight. It, also, describes the process of raising chicks to a fully grown state by the chick's parents. A young bird that has recently fledged but is still dependent upon parental care and feeding is called a fledgling that feels comfortable in its own fledgling bird house.

In ornithology, the meaning of fledgling can mean different things, depending on the particular species. Birds are sometimes considered fledged once they leave the nest even if they still cannot fly. However, usually a fledgling is considered a chick that is independent from an adult because, very often, adults will continue to feed the chick after it has left the nest and is able to fly.

The murrelet fledges two days after hatching, running from its burrow to the ocean and its calling parents. Once it reaches the ocean it is cared for several weeks by its parents. Other species, such as guillemots and cormorants leave the nesting site before they are, barely, able to fly. The behavior of the guillemot fledgling is interesting. The adult will lead the chick to a large drop like a cliff. The adult will, then, fly down and call to its young. The chick will launch itself off the cliff attempt to fly as far as possible, crash land on the ground below before continuing its run towards the ocean.

Baby birds often look different from the adults, if only in the body proportions. Some fledglings look so different from the adult that their species are difficult to identify. Baby birds typically have very brightly colored bill and throat linings. As a chick opens its mouth to vocalize or beg, the parent bird sees a flash of orange, red, or yellow--a "target zone" that shows where to stuff the next juicy grub or worm. In many altricial species, born helpless and naked when hatched as in the Eastern Tufted Titmouse, fledglings temporarily retain colored target zones that change to gray or white or even black as the youngster matures.

The bright color of a nestling's mouth lining typically extends to the edge of the bill and to the juncture of the upper and lower mandibles--an area known as the "gape." In young birds, the gape is very soft and noticeable but in a fledgling it begins to harden somewhat, become less prominent, and--like the bill itself--darken with age. In some bird species such as the Purple Finches, the adult retains a yellow gape, albeit smaller and less obvious. In some bird species, young birds exhibit a remarkable change in bill color. In some birds such as the fledgling cardinal, the bill is very dark. It, eventually, becomes bright orange as the youngster begins to forage on seeds and berries containing carotene it lays down in the bill sheath. Strangely, adult cardinals quit processing yellow-orange pigment during the non-breeding season, so bill color in winter birds gradually fades until it resembles that of juveniles. The same phenomenon occurs in the American Goldfinch.

Page 1 of 2 :: First | Last :: Prev | 1 2 | Next